The Causes of Autism

What causes the condition to wax and wane.

The origins of autism have been hypothesized to be genetic in nature, environmental or a combination of the two. This website proposes and discusses a specific theory of the origins of autism that stems from an expanded theory of human evolution that places a heavy emphasis on sexual selection, social structure, neoteny, and uterine testosterone and estrogen levels in human development. By understanding how humans evolved, we can gain insight into autism as a condition with roots in our evolutionary past. To understand the cause of autism we have to explore the origin of our species.

This blog also discusses other theories on the cause of autism addressing current developments in a casual format. See for several dozen short essays on autism and related subjects. Visit for a more extended treatment of how autism and evolution interact.

New Study and Increased Rates

A study just released, Prevalence of Autism Spectrum Disorders — Autism and Developmental Disabilities Monitoring Network, United States, 2006, describes an increase in autism in the United States among 8 year olds in 2006. An interesting aspect of the study is the higher incidence of the condition among whites vs. blacks and Hispanic children.

ASD prevalence also varied by race and ethnicity (Table 2). Combining data from all sites, the average prevalence among non-Hispanic white children (9.9; CI = 9.4–10.4) was significantly greater than that among non-Hispanic black children (7.2; CI = 6.6–7.8) and Hispanic children (5.9; CI = 5.3–6.6) (Table 2) (p<0.001). For five (Florida, Georgia, Missouri, North Carolina, and Wisconsin) of the 11 ADDM sites, ASD prevalence was significantly higher among non-Hispanic white children than among non-Hispanic black children (p<0.05). ASD prevalence was significantly lower among Hispanic children than among non-Hispanic white children in six sites (Alabama, Arizona, Georgia, Missouri, North Carolina, and Wisconsin), and was significantly lower than prevalence among non-Hispanic black children in four sites (Alabama, Arizona, Colorado, and Georgia).

My works hypothesizes that if autism is an evolutionary condition with testosterone compelling return to forebear neurologies when equatorial peoples are moved to Northern climes, then blacks and Hispanics should evidence autism more frequently in the Northern U.S..

The male/female ratio varied dramatically depending on where you were in the country. I don’t know how to interpret that.

Geschwind, Galaburda and Autism

The literature on stuttering repeatedly refers to allergies (Diehl 1958; Szondi 1932); pediatric neurologists have repeatedly told us of the high frequency of migraine in dyslexics; Coleman (1976) discussed the high rate of a gut-related disorder in autism (p. 92). (Geschwind, N. & Galaburda, A.M. (1987). Cerebral Lateralization. Cambridge:  MIT Press.)

Geschwind and Galaburda’s Cerebral Lateralization was very influential for a short period of time. Supporting studies were often contrasted with studies that supported competing theories. Nevertheless, sense has been emerging from the conflicting studies. Baron-Cohen’s work represents much of that sense.

Perhaps by offering additional attention to the influence of the sexual hormones upon both specific symptoms (such as migraine) and conditions that exhibit maturational delay or acceleration (such as autism and stuttering) we can understand the connection between maturity and physical disorders.

Allergies and Autism

In addition to the reports mentioned earlier of increased frequency of allergies among stutters, celiac disease among autistic children and autoimmune thyroid disorders in their parents, and migraine among childhood dyslexics, a high frequency of food allergies (Tryphonas and Trites 1979) and atopic disorders (Geschwind and Behan 1984) have been reported among hyperactive children (p. 94). (Geschwind, N. & Galaburda, A. M. (1987). Cerebral Lateralization. Cambridge: MIT Press.)

Geschwind and Galaburda’s Cerebral Lateralization is crammed with information that suggests an etiology for autism. It is the first place that I know of that associated autism with a mother’s testosterone levels. When the book discusses allergies and autism, I am reminded that perhaps a mother’s allergies influence her testosterone, or even estrogen levels, and that those changing levels increase chances for conditions featuring maturational delay. I’ve wondered if the recorded season of birth effects associated with autism are related to when a mother’s allergies correlate with certain points in pregnancy when maturation rates are established.

Autism and Evolutionary Precursors

OBJECTIVE: Several studies report a greater than expected concurrence for Tourette’s syndrome (TS) with autistic disorder (AD). TS and bipolar disorder (BD) also may co-occur at a greater than expected rate. The authors assess whether there is a greater than expected concurrence for TS+AD+BD. METHOD: Four patients who had at some time in their lives diagnoses of TS, AD, and BD were identified. Three of these had concurrent TS+AD+BD. Diagnoses were made according to DSM-III-R criteria. Each of these patients was living in North Dakota and was in the authors’ care at the time of this study. RESULTS: The point prevalence (risk) for concurrent TS+AD+BD in North Dakota is not less than 4.6 x10(-6). The developmental sequence of syndromes in these four patients was AD, then TS and then BD. Data from the authors’ previously published, population-based prevalence studies indicate that TS+AD+BD co-occur at a greater than chance expectation. CONCLUSIONS: Common etiological factors may be involved in the greater than chance concurrence of TS+AD+BD. (Kerbeshian, J. & Burd, L. (1996). Case study: Comorbidity among Tourette’s syndrome, autistic disorder, and bipolar disorder. Journal of the American Academy of Child Adolescent Psychiatry, 35(5), 681-5)

A question that often crosses my mind is if autism and Tourette’s are both conditions with evolution origins, is Tourette’s a precursor to autism? Or, do they represent two different forebear evolutionary branches.

A not uncommon feature of Tourette’s is obsessive compulsive disorder. A man with Tourette’s I know compulsively self grooms, picking at tiny flecks upon his person. When a woman walks into a room he often emotes unique noises. This man is also brilliant and uncommonly strong.

This particular person was displaying possible features of a human progenitor. If autism and Tourette’s are related, as this study suggests, what features of autism might suggest precursor?

Vitamin D and Autism

As this post from yesterday’s Autisable notes, Vitamin D has been becoming more accepted as a possible explanation for some forms of autism. I’ve been proposing that light’s effect on the pineal gland has been regulating testosterone levels in directions that can cause autism, predicting in 1998 ( that equatorial populations moving to northern climes would evidence higher percentages of autism.

Both my pineal theory, based on fluctuating testosterone levels, and the Vitamin D theory suggest that there would be clear season of birth effects with autistic children being conceived in certain times of the year. I’ve not seen studies that support that prediction.

Twins and Autism

Previous studies have suggested that among affected sib pairs with autism there is an increase in the frequency of twins over what would be expected in comparison to the prevalence of twins in the general population. In this study we sought to determine whether sub-threshold autistic traits were more pronounced in twins than in non-twins. The Social Responsiveness Scale (SRS) was administered in an epidemiologic twin sample (n=802) and in a separate population-based sample of non-twins ascertained from a local school district (n=255). For males (but not females), the mean SRS score was significantly higher among twins than among non-twins. As has been suggested for autism, twin status may incur increased liability to subthreshold autistic symptomatology, particularly in males. (Ho, A., Todd, R. D. & Constantino, J. N. (2005). Brief report: Autistic traits in twins vs. non-twins–a preliminary study. Journal of Autism and Developmental Disorders, 35(1), 129-33.)

Higher incidence of autism among twins, of course, suggests genetic origins, though embronic environmental influences come into play. A couple things come to mind reading this passage.

Studies seeking genetic causes of autism point to twins studies as integral to their conclusion that autism is largely a genetic condition. Nevertheless, the relationship between genetics and environment is still very much in flux. Evolutionary developmental biology is just beginning to open those doors.

Second, is there a smaller percentage of identical female twins with at least one twin exhibiting autism or Aspergers than the normal percentage of females to males? In other words, if it is a 4/1 ration male/female, and the number of males to females that are autistic that are identical twins is different that 4/1, then perhaps the etiology of female autism is significantly different than male autism.

Autism, Brain Size and Maturation

Increased brain size has been observed in individuals with autism with a wide range of cognitive functioning. The purpose of this investigation was to obtain measurements of the brain volume in a sample of nonmentally retarded autistic individuals. Magnetic resonance imaging scans from 16 nonmentally retarded individuals with autism and 19 male volunteer comparison subjects were obtained and the following structures were measured: third, fourth, and lateral ventricles and intracranial and cerebral volumes. Mean cerebral and third ventricle volumes in the autistic subjects were significantly greater than in the controls when adjusted for intracranial volume. No other significant results were found. Our finding of increased brain volume in autism is consistent with previous reports in the literature. Additional longitudinal neuroimaging and, more importantly, neuropathologic studies are warranted to provide a better understanding of the complexities underlying increased brain size in autism. (Harden, A. Y., Minshew, N. J., Mallikarjuhn, M. & Keshavan, M. S. (2001). Brain volume in autism. Journal of Child Neurology, 16(6), 421-4.)

Studies continue to be published that call attention to possible genetic causes of autism. Yet, a larger brain size in many of those that are autistic is not explored in the context of evolutionary changes over time.

Over the last 25 thousand years human brain size has grown smaller. Consider that if autistics have larger brains, they are neurological retreats to a slightly older neurological convention.

Instead of examining genes for autistic tendencies, perhaps we should be exploring the connection between evolution and ontogeny, brain size being related to maturation.

Autism and Handedness

Twenty-six autistic children, constituting a total population sample of children diagnosed in accordance with Rutter’s criteria as suffering from infantile autism, were assessed with regard to handedness and certain associated factors. They were compared with 52 age-, sex-, and IQ-matched controls. Sixty-two percent of the autistic children were non-right-handed compared with 37% of the controls. Left-handedness in autism was associated with an abundance of delayed echolalia. Heredity for left-handedness in some cases, and assumed brain damage and immature patterns of lateralization in others, were considered the cause of non-right-handedness in the autistic children. Computed tomographic (CT) brain scans and other neurobiological examinations did not provide evidence indicating clear-cut unilateral left hemisphere dysfunction in autism. Rather, a slight trend in the opposite direction (i.e., an association with right hemisphere dysfunction) was seen in the left-handed autistic children. The result points toward the need for further studies of handedness in autism. (Gillberg, C. (1983). Autistic children’s hand preferences: Results from an epidemiological study of infantile autism. Psychiatry Research, 10(1), 21-30.)

Twenty five years ago researchers observed the close connection between autism and handedess. A generation later and the connection between handedness and Marian Annett’s work regarding random handedness as an evolutionary precurser to contemporary right handedness has not been explored as related to autism. If autism is an evolutionary condition, and we understand evolution as a process deeply influenced by social structure and environmental effects, then perhaps we can understand what causes some forms of autism.

Autism and Genetics

A review of the current literature suggests that genetic factors play an important role in the etiology of autism. It is likely that the etiology of currently idiopathic cases of autism will be shown to be heterogeneous, just as the few known etiologies are both environmental and genetic. Moreover, we would speculate that within the group of cases shown to have genetic etiologies, more than one genetic locus will be found. Some evidence suggests that quite often it is not autism itself that is inherited but rather some genetic abnormality of language or sociability that interacts with other factors to produce autism. (Folstein, S. E. & Rutter, M. L. (1988) Autism: Familial aggregation and genetic implications. Journal of Autism and Developmental Disorders, 18(1), 3-30.0

Google alerts me every day to articles emerging about autism. Many of those articles allude to papers published calling attention to possible genetic causes of autism.

Susan Oyama writes about the challenges our society creates confusing genetic and environment causes, nature and nature, by often really thinking in terms of genetics but stating both are in play. If feels to me that this is often an issue in autism research. We understand so little the impact of ontogeny upon unique conditions that we instead concentrate on genetics which looks like a code to decipher, not a pattern to resolve.

Understanding ontogeny as evolutionary as its foundation, perhaps we can reinterpret autism as an evolutionary condition and then see how genetics are in play.

Autism & Early Intervention

A recent article in Science Blog described a study pubished in Pediatrics that discussed the Early Start Denver Model, “which combines applied behavioral analysis (ABA) teaching methods with developmental ‘relationship-based’ approaches.”

“This is the first controlled study of an intensive early intervention that is appropriate for children with autism who are less than 2½ years of age. Given that the American Academy of Pediatrics recommends that all 18- and 24-month-old children be screened for autism, it is crucial that we can offer parents effective therapies for children in this age range,” said Geraldine Dawson, Ph.D., chief science officer of Autism Speaks and the study’s lead author. “By starting as soon as the toddler is diagnosed, we hope to maximize the positive impact of the intervention.”

It comes to mind again the relavance of making ontogenetic interventions (early childhood interventions) without an evolutionary model. How might an understanding of what humans needed several thousand generations ago be connected to what a toddler needs today? This seems particularly important when working on language, socialization, and theory of mind issues.

Consider a model of early childhood delelopment connected to evolutionary development, not unlike the exact paradigm Piaget played with, except one that takes into consideration particularly practices that might be necessary for those having difficulty with the conventional transitions.

Autism and Social Stresses

Reviews research relevant to the questions of whether childhood schizophrenia and infantile autism are evenly distributed across the population of the world or even across a single society, whether social selection or social causation may operate in their occurrence, and whether there is a relationship between social class and infantile autism. Studies examined include early investigations in the US and UK on the possible importance of social background and parental behavior in childhood schizophrenia; studies conducted in continental Europe, Africa, Asia, and Australia; studies of Blacks and Hispanics in the US; and investigations suggesting that parental socioeconomic status (SES) may be more important than ethnicity in the development of childhood psychoses. It is concluded that evidence supports the speculation that problems of modern living, particularly the nuclearization of the family, are likely to increase the stresses experienced by the infant. (Sanua, V. D. (1981). Autism, childhood schizophrenia and culture: A critical review of the literature. Transcultural Psychiatric Research Review, 18, 165-81.)

The question is, what are the nature of these “stresses”. Social structure is rarely examined for the impact that it has upon the hormonal distribution of  populations. If it is true that testosterone and estrogen levels are integral in the etiology of autism and conditions exhibiting maturational delay and acceleration, then perhaps we should explore what influences those hormone levels.

Bernard Crespi and Autism

It was noted yesterday that Bernard Crespi and colleagues have released further findings suggesting a relationship between schizophrenia and autism. At I’ve written about Crespi’s work and where I agree with the direction he is taking.

Crespi and I both believe that how brains lateralize and the width of corpus callosum connections influence the etiology of both conditions. I suggest that the origin of human split consciousness or self awareness is also integrally connected to these issues. We are both approaching this from an evolutionary perspective.

Whereas autism displays features of primary process or humans perhaps 4000 generations ago, I hypothesize that some forms of schizophrenia represents an opposite of primary process or a human so split, so self aware, they can’t easily encourage both sides to work together.

Crespi’s conclusion that autistic brains are larger, schizophrenic’s smaller, support this way of looking at the information.

Infection, Allergies and Autism

The possibility of intrauterine infections as a plausible explanation for the increased autism prevalence in children born to immigrant mothers is relevant. Hypothetically, mothers arriving from a totally different culture may not have been exposed to the same type of infections as have native mothers. This explanation would only hold if the mothers had lived in the immigrant country from at least the second trimester (the period during which infection by agents to which the mother is not immune would damage the brain in ways which would lead to autistic symptomatology). This applied in all three cases in the present study.  [pp. 143-4] (Gillberg, C., Schaumann, H. & Gillberg, I. C. (1995). Autism in immigrants: Children born in Sweden to mothers born in Uganda. Journal Of Intellectual Disability Research: JIDR, 39(Pt. 2), 141-4.)

Season of birth effects have the potential to make clearer the cause of autism in equatorial populations migrating to Northern climes. If those with autistic tend to be born in certain months, several etiologies are suggested.

One in the Vitamin D hypothesis. Another is the influence of the pineal gland on testosterone levels.

Related in the possibility that allergies are causing autism, allergies in a pregnant mother. How to allergies influence testosterone levels? Do the stress they cause increase testostesterone levels? Are children conceived at certain times more vulnerable to autism when mothers are highly allergic in the fall?

If maturation rates are set at a specific time in gestation, what influences testosterone levels at that time may be encouringing autism. How much effect does infection and allergies have upon uterine testosterone levels?

Autism and Immigration

Lotter (1978) examined children attending services in nine major cities in sub-Saharan African countries. He found fewer children with autism than expected (as compared with prevalence rates in industrialized countries). However, as Lotter noted (and as highlighted by Wing 1993), it was not possible to carry out a proper prevalence investigation in the area concerned. Interestingly, there was a marked excess of children with autism who had parents who had lived abroad for any period of time (indicating a possible relationship between autism and migration).  [p. 143] (Gillberg, C., Schaumann, H. & Gillberg, I. C. (1995). Autism in immigrants: Children born in Sweden to mothers born in Uganda. Journal Of Intellectual Disability Research: JIDR, 39(Pt. 2), 141-4.)

Parents returning home had autistic children more often than those that never left. This begs several questions. Does this effect influence both moms and dads? Were the autistic children gestated overseas? What was the influence of latitude (was there more autism among parents that were coming back from extreme Northern or Southern climes)? If parents conceived and gestated children both locally and far away, what was the difference in autism?

Parents that immigrated to Northern and Southern locations, are there opposite season of birth effects?

Ugandan and Somali Autism

Three boys diagnosed as suffering from autistic disorder were born in Sweden to mothers born in Uganda. Two were related but the third boy was unrelated to the others. The prevalence for autistic disorder in Göteborg children born to mothers who were born in Uganda was 15% which is almost 200 times higher than in the general population of children. The possible reason for the high autism rate in this particular ethnic subgroup is discussed. (Gillberg, C., Schaumann, H. & Gillberg, I. C. (1995). Autism in immigrants: Children born in Sweden to mothers born in Uganda. Journal Of Intellectual Disability Research: JIDR, 39(Pt. 2), 141-4.)

Somali and Ugandan autism rates skyrocket when children are born in Northern latitudes like Sweden and Minnesota. If light is having an impact, we would expect to see season of birth effects. Both the Vitamin D and testosterone/pineal theories, based upon light, should be revealing season of birth effects.

Another question would be, are mothers and fathers immigrating from equatorial regions to Northern climes having autistic children in larger numbers? What happens when couples with Indonesia immigrate to Scandinavia and Minnesota?

Autism, Vaccines and Neoteny

This study was prompted by findings reported to the Institute of Medicine by Blaxill in July 2001, which showed increases in autism incidence in California in association with increases in the use of thimerosal-containing vaccines during the 1990s. To further examine the plausibility of this finding, this study took advantage of the cessation of thimerosal use in Denmark and Sweden in 1992 to conduct a before and after comparison of the incidence or case numbers of autism. In both countries, autism increases throughout the years 1987-1999, contrary to the decrease in autism that would be expected after 1992 if thimerosal exposure was related to autism. The increasing trend for autism is most notable in Denmark where the number of autism cases rises substantially even after the discontinuation of thimerosal use. (Stehr-Green, P., Tull, P., Stellfeld, M., Mortenson, P. B. & Simpson, D. (2003). Autism and thimerosal-containing vaccines: Lack of consistent evidence for an association. American Journal of Preventative Medicine, 25(2), 101-6)

Vaccines are easily the most widely discussed controversial cause of autism. I assume autism has several causes, concentrating on those that influence rates of maturation. Vaccines haven’t seemed relevant to the particular focus my work addresses, evolutionary causes.

The excerpt above notes surges in autism in Denmark and Sweden. It hadn’t crossed my mind until now, but it makes sense that increases in autism would most likely occur in Northern climes (encouraged by the pineal/testosterone connection, light influencing testosterone levels based on seasonal effects) and in Scandinavia where the populution already exhibits neoteny in both sexes.

I would guess that Scandninavian autism would have larger percentages of males to females with autism, what with females displaying neoteny as opposed to acceleration.

Autism and Womb Dynamics

Ploeger’s research reveals that in the period between 20 and 40 days after fertilisation, the embryo is highly susceptible to disruptions. In this period, early organogenesis, there is a lot of interaction between the different parts of the body. If something goes wrong with a given part of the body, it greatly influences the development of other parts of the body. As people with schizophrenia and autism frequently have physical abnormalities to body parts formed during early organogenesis, Ploeger concluded that the foundation for these psychiatric disorders is laid very early during pregnancy…The existence of a relationship between unhealthy behaviour during pregnancy and the subsequent development of schizophrenia and autism in the child was already known. However, Ploeger’s hypothesis that the early organogenesis stage is the most critical, is new. Ploeger bases her hypothesis on an extensive study of scientific literature in this area. She often had to make use of related studies; although a lot of research has been done into prenatal influences on the development of schizophrenia and autism, little is known about the influence that the period between 20 to 40 days after fertilisation has. (Ploeger, A. (2008). Autism and schizophrenia share common origin [PhD Thesis]. Retrieved on Dec. 17, 2008 from

Simon Baron-Cohen’s work concluding that a mother’s uterine testosterone levels may be influencing the chance of autism suggests the question of what point or points during gestation does a mother’s testosterone levels have an effect. If indeed a child’s maturation rates are influenced by a mother’s testosterone levels, when does that occur?

Perhaps the most frustrating experience I’ve had as someone exploring these issues is my having lost the citation that states that a child’s maturation rate is influenced by a mother’s testosterone levels at six weeks before birth. The conclusion may be related to children born premature. If born before six weeks, a child exhibits a number of derivations, some possibly related to maturation rate.

Knowing at what point maturation rates are established, if guided by mother’s testosterone levels, provides an opportunity to explore environmental influences impacting a mother’s testosteron levels.

Autism and Schizophrenia

Developmental psychologist Annemie Ploeger has investigated whether there is a connection between disorders in the first month of pregnancy and the development of schizophrenia and autism. Interestingly, many physical abnormalities of autistics are also prevalent in schizophrenics. For example, both autistics and schizophrenics sometimes have protruding ears and peculiar toes. There are also differences: a large head and intestinal problems, for example, are typical traits occurring in autistics. From this, Ploeger concluded that the two disorders share a common origin. The same error that occurs very early in pregnancy develops into autism in one individual and schizophrenia in another. (Ploeger, A. (2008). Autism and schizophrenia share common origin [PhD Thesis]. Retrieved on Dec. 17, 2008 from

Bernard Crespi’s Psychosis and Autism as Diametrical Disorders of the Social Brain also finds patterns that bridge schizophrenia and autism. Yet schizophrenia seems to display more than one lateraterlization convention and varying corpus callusum widths and lengths depending on the study being explored.

I suspect the schizophrenia, like autism has more than one etiology. Some forms may be closely related to autism as an evolutionary condition. Other forms perhaps early brain trauma related. Schizophrenia timing onset can be related to pubertal timing and differs between the sexes. This feels like a major clue as regards connections to testosterone and estrogen levels.

Autism Causes and Birth Order

Cocaine in all forms is the number one illicit drug of choice among pregnant women. Records of 70 children with cocaine exposure in utero who were referred for developmental evaluation at a large inner-city hospital were reviewed in an effort to determine whether a specific pattern of abnormalities could be discerned. Patients received physical examinations, neurological screenings, and behavioral and developmental assessments based on the Gesell Developmental Inventory, and the Denver Developmental Screening Test. Documentation of specified drug use was obtained by history. Mean age (SEM) at referral was 19.2 (1.7) months. All mothers used cocaine in one of its forms, although polydrug use was common. Growth parameters were low (median = 15th percentile). Significant neurodevelopmental abnormalities were observed, including language delay in 94% of the children and an extremely high frequency of autism (11.4%). The high rate of autistic disorders not known to occur in children exposed to alcohol or opiates alone suggests specific cocaine effects. (Davis, E., Fennoy, I., Laraque, D., Kanem, N., Brown, G. & Mitchell, J. (1992). Autism and developmental abnormalities in children with perinatal cocaine exposure. Journal of the National Medical Association, 84(4), 315-19).)

A recent study noted that both first born and late born children exhibited greater tendencies toward autism than children in the middle. As a woman grows older her testosterone levels increase. This might explain more autistic children coming to older mothers. Why are firstborn often autistic?

One reason may be that this is the most difficult of births, and often pregnancies. Autism, besides being a condition with genetic causes, is caused by such effects as mother’s use of cocaine. It could be explored whether autistic children of older mothers vs. firstborns come from families of left handers, or families displaying OCD, borderlines, or narcissists an equal amount of the time. (Those conditions are associated with autism in family of origin.)

Also, how often do mothers giving birth to an autistic child as their first child choose to have no other children? This would skew the statistics.

Autism, Testosterone and Estrogen

“…When the children were followed-up after birth, those children with higher levels of foetal testosterone had lower rates of eye contact and were slower to develop language, as toddlers.  In primary school they had more social difficulties and reduced empathy, and they also had stronger interests in systemizing…These studies looked at individual differences in otherwise typically developing children.  We cannot yet conclude that elevated rates of foetal testosterone cause autism or Asperger syndrome, as the children in these studies do not have a diagnosis.  It is of interest that using the Child AQ (Autism Spectrum Quotient)…completed by the mother, those children with higher levels of foetal testosterone also had a higher score on the AQ (more autistic traits).  But the test of the foetal androgen theory will come when large enough samples of amniotic fluid are available, with follow-up data relating to actual diagnosis.” [p. 95] (Baron-Cohen, S. (2008). Autism and Asperger syndrome: The facts. New York: Oxford University Press.)

Geschwind and Galaburda (1987) hypothesized that testosterone influenced cerebral lateralization, handedness and a number of diseases and conditions including autism. Baron-Cohen and colleagues have discovered what seems like direct connections between a mother’s testosterone levels and autism and Aspergers. A question is, is estrogen influential in this mix?

If estrogen levels impact the timing of puberty, influening testosterone surges, does estrogen impact the timing of infant synapse pruning that comes from testosterone surges. That pruning may have a lot to do with handedness and cerebral lateralization. Lateralization seems related to autism with 20% of children with autism displaying brains at the 95 percentile with right hemispheres that seemed not to have ever been pruned by testosterone surges.

Autism Percentages

“…The striking ratio of males to females among individuals with the condition [autism].  The sex ratio of males to females reported in the literature ranges from approximately 2:1 to 4:1 (Lord and Schopler 1987; Wing 1981), and approximately 9 times as many males as females are diagnosed with Asperger’s syndrome (which can be viewed as a milder form of autism).” [p. 39] Baron-Cohen, S. (2008). Autism and Asperger syndrome: The facts. New York: Oxford University Press.

If there a larger number of females to males in Aspergers than there are in autism, the percentage of males with ASD will increase with an increase in the number of children diagnosed. Unless the evaluation protocol is revised which is now being considered. If Aspergers is separated from autism as a diagnosed condition the numbers will likely become more difficult to parse.

I believe that autism is an evolutionary condition influenced by changes in social structure. I hypothesize that females evolved sooner than males to achieve split consciousness evidenced by cerebral lateralization. When social structure and environmental forces compel the emerence of evolutionary forebear features, we have to go further back to find woman challenged in the same way that men are when wrestling with the transition to the new brain of the split conscious human being.

Current ratios reflect evolutionary pathways.

Autism, Testosterone and Estrogen?

Testosterone promotes male-typical neural and behavioral development in non-human mammals. There is growing evidence that testosterone exerts similar influences on human development, although the range of behaviors affected is not completely known. This study examined the hypothesis that autistic traits are increased following prenatal exposure to abnormally high levels of testosterone caused by congenital adrenal hyperplasia (CAH). Sixty individuals with CAH (34 female, 26 male) and 49 unaffected relatives (24 female, 25 male) completed the Autism Spectrum Quotient (AQ). Females with CAH scored significantly higher than unaffected females on total AQ score, largely due to enhanced scores on subscales measuring social skills and imagination. These results suggest that prenatal exposure to high levels of testosterone influences some autistic traits and that hormonal factors may be involved in vulnerability to autism. (Knickmeyer, R., Baron-Cohen, S., Fane, B. A., Wheelwright, S., Mathews, G. A., Conway, G. S., Brook, C. G. & Hines, M. (2006). Androgens and autistic traits: A study of individuals with congenital adrenal hyperplasia. Hormones and Behavior, 50(1), 148-53.)

I’m not finding much in the way of reference to estrogen and causes of autism. When Geschwind and Galaburda opened up discussion in the direction of testosterone in the 1980’s, it was in the context of testosterone influencing cerebral lateralization, or what I would describe as the rate of maturation. Other the Tim Crow, no academic was citing the heterochronists or those that specialize in the rate and timing of maturation as regards cerebral lateralization.

Estrogen does not enter the discussion because estrogen is not normally associated with the timing of maturation. If estrogen influences timing, then autism may be influenced by estrogen levels if degrees of cerebral lateralization are influenced by estrogen and degrees of cerebral lateralization is related to autism.

Autism, Melatonin, the Pineal, Testosterone and MN Somalis

Melatonin is produced in the dark by the pineal gland and is a key regulator of circadian and seasonal rhythms. A low melatonin level has been reported in individuals with autism spectrum disorders (ASD), but the underlying cause of this deficit was unknown. The ASMT gene, encoding the last enzyme of melatonin synthesis, is located on the pseudo-autosomal region 1 of the sex chromosomes, deleted in several individuals with ASD. In this study, we sequenced all ASMT exons and promoters in individuals with ASD (n=250) and compared the allelic frequencies with controls (n=255). Non-conservative variations of ASMT were identified, including a splicing mutation present in two families with ASD, but not in controls. Two polymorphisms located in the promoter (rs4446909 and rs5989681) were more frequent in ASD compared to controls (P=0.0006) and were associated with a dramatic decrease in ASMT transcripts in blood cell lines (P=2 x 10(-10)). Biochemical analyses performed on blood platelets and/or cultured cells revealed a highly significant decrease in ASMT activity (P=2 x 10(-12)) and melatonin level (P=3 x 10(-11)) in individuals with ASD. These results indicate that a low melatonin level, caused by a primary deficit in ASMT activity, is a risk factor for ASD. They also support ASMT as a susceptibility gene for ASD and highlight the crucial role of melatonin in human cognition and behavior. Melke, J., Goubran Botros, H., Chaste, P., Betancur, C., Nygren, G., Anckarsater, H., Rastam, M., Stahlberg, O., Gillberf, I. C., Delorme, R., Chabane, N., Mouren-Simeoni, M. C., Fauchereau, F., Durand, C. M., Chevalier, F., Drouot, X., Collet, C., Launay, J. M., Leboyer, M., Gillberg, C. & Bourgeron, T. (2008). Abnormal melatonin synthesis in autism spectrum disorders. Molecular Psychiatry, 13(1), 90-8.

I occasionally write of the Geschwind and Galaburda inspired conjectures that autism is influenced by fluctuating mother uterine testosterone levels in connection to populations immigrating from equatorial regions to Northern climates. Pineal gland responses to light impact testosterone levels to behave as if an individual is still in Africa experiencing diurnal light cycles of 30% fluctuations, excepts changes ebb and flow seasonally, not daily. This could explain Minnesota Somali autism.

Melatonin is part of this equation, acting as intermediary between the pineal gland and fluctuating hormone levels. When the autistic show deficits in melatonin, consider the possibility that this is directly connected to the effects of light.

What might be the melatonin levels of the Somali autistic and their siblings?

Writing and Drawing

Researchers at the Johns Hopkins School of Medicine in Baltimore have been exploring handwriting and children with autism and Aspergers. They discovered their handwriting was poorer than that of children without the condition.

I maintain two different ways of writing that exhibit two dramatically different results. I can write as I subvocalize, letting the words pour out my fingers. The result is almost unintellible. I often can not read my own writing. Or, I can draw my words. When I draw my words I am making pictures that represent the letters that have meaning. When I draw my words they are not only readable but notably attractive.

Having had several Aspergers aspects to my personality when I was young, I was often considered one of the two best artists in my class, worst speller, and worst penmanship. Buddy Whit Watts, was also a good artist and bad speller. There is a pattern here.

I think it has to do with being good at symbol but not at sign. As beings still mostly familiar with primary process (one time, one place, no opposites) the autistic can experience one thing representing another in a fashion that the two are the same, but they are not good at split consciousness where one thing is associated with other things, but they are not the same.

Writing is not drawing. Understanding the difference suggests an understanding of the different consciousnesses associated with the two.

Schizophrenia and Autism

To limit genetic heterogeneity, this study focused on the widely extended pedigrees of Ashkenazi Jewish schizophrenic and autistic probands, to determine if similar causal mechanisms might obtain for both conditions. At least two previous epidemiological studies have demonstrated increased risk for schizophrenia in Ashkenazi Jews. The hypothesis posed is that increased prevalence of various rare autosomal recessive diseases among the Ashkenazim might contribute to the increased vulnerability to schizophrenia and to autism in this large genetic isolate. Rates of amyotrophic lateral sclerosis (ALS) and bleeding disorders were significantly increased among relatives of schizophrenic and autistic probands, compared to relatives of normal probands. These results suggest new candidate loci in schizophrenia and autism, particularly the chromosome 15q23-24 locus of the hexosaminidase A gene, causing various GM2 gangliosidoses, and the 21q22.1-q22.2 loci of the antioxidant, superoxide dismutase gene, and a cytokine receptor gene. (Goodman, A. B. (1994). A family history study of schizophrenia spectrum disorders suggests new candidate genes in schizophrenia and autism. The Psychiatric Quarterly, 65(4), 287-97.)

A number of studies have suggested a relationship between schizophrenia and autism, perhaps most recently Psychosis and Autism as Diametrical Disorders of the Social Brain by Bernard Crespi. It seems that schizophrenics and autistics often share family of origin, even though the brain structure and behaviors are not alike. If autistics often come with the first born and latest children of a mother, do schizophrenics have a similar birth order pattern?

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