Sex differences in autism

From Wikipedia, the free encyclopedia
Jump to navigation Jump to search

Males are more frequently diagnosed with autism than females, but it is debated whether this is due to a sex difference in rates of autism spectrum disorders (ASD) or whether females are underdiagnosed. The prevalence ratio is about 4 males for every 1 female diagnosed.[1] Currently, one in every 42 males and one in 189 females in the United States is diagnosed with autism spectrum disorder.[2] There is some evidence that females may also receive diagnoses somewhat later than males, however thus far results have been contradictory.[3]

Several theories exist to explain the sex-based discrepancy, such as a genetic protective effect,[4][5][6] the extreme male brain theory[7][8] and phenotypic differences in the presentation between sexes,[6][9][10][11] which may all be intertwined. Researchers have also debated whether a diagnostic gender bias has played a role in females being underdiagnosed with autism spectrum disorder.[12] Researchers have also speculated a gender bias in parental reporting due to the expectations and socialization of gender roles in society.[13]

Since autism is a largely genetic and hereditary condition, genetic factors that can affect sex disparity with medical conditions come into play and include imprinting and X-linked mutations, which would have the ability to raise the frequency and severity in males and confer the hypothesised genetic "protective effect" in females, as they do in other conditions. Simon Baron-Cohen's extreme male brain theory suggests that autistic brains show an exaggeration of the features associated with male brains, such as increased size and decreased relative connectivity as well as systematic thinking over empathetic thinking.[14] The imprinted brain theory suggests genomic imprinting is at least partly responsible for the sex differences in autism and points to the evidence for a common genetic cause with schizophrenia,[15][16][17] together with the increased prevalence and severity of schizophrenia in males,[18][19][20] which is also reflective of the variability hypothesis, which states that there is greater variability in traits, especially intelligence, among males.

There is evidence of increased incidence of social anxiety,[10] anorexia nervosa[21][22] and self-harm in autistic females,[23] though the increased rates of anorexia nervosa may be due to confusion or conflation with avoidant/restrictive food intake disorder (ARFID), which is particularly common in autism.[24]

Extreme male brain theory[edit]

Simon Baron-Cohen's extreme male brain theory states that autistic males have higher doses of pre-natal testosterone and on average have a more systemising brain, as opposed to the more empathising female brain. He suggests that autistic brains show an exaggeration of the features associated with male brains. These are mainly size and connectivity, with males generally having a larger brain,[14] which is seen in an exaggerated form in those with ASD. Individuals with ASD were found to have widespread abnormalities in interconnectivity in specific brain regions.[25] This could explain the different results on empathy tests between men and women[26] as well as the deficiencies in empathy seen in ASD, as empathy requires several brain regions to be activated which need information from many different areas of the brain.[27] Baron-Cohen therefore argues that genetic factors play a role in autism prevalence and that children with technically minded parents are more likely to be diagnosed with autism.[28]

Imprinted brain theory[edit]

The imprinted brain theory suggests genomic imprinting is at least partly responsible for the sex differences in autism and implicates schizophrenia as well, referencing the fact that the current genetic and physiological evidence suggests the two conditions are on a spectrum in which some mutations in certain genes cause lower social cognition but higher practical cognition (autism) while others in the same genes cause lower practical cognition with higher social cognition (schizophrenia).[15][16][17] It is already known that schizophrenia is more prevalent and more severe in males than females.[18][19][20] This is also reflective of the variability hypothesis, which states that there is greater variability in traits, especially intelligence, among males.

Female protective effect hypothesis[edit]

According to the female protective effect hypothesis, more extreme genetic mutations are required for a girl to develop autism than for a boy. In 2012, Harvard researchers published findings suggesting that, on average, more genetic and environmental risk factors are required for girls to develop autism, compared to boys. The researchers analyzed DNA samples of nearly 800 families affected by autism and nearly 16,000 individuals with a variety of neurodevelopmental disorders. They looked for various types of gene mutations. Overall, they found that females diagnosed with autism or another neurodevelopmental disorder had a greater number of harmful mutations throughout the genome than did males with the same disorders.[29]

Hypothesis of female underdiagnosis[edit]

Some authors, clinicians and experts like Judith Gould, Tony Attwood, Lorna Wing and Christopher Gillberg[30] have proposed that autism in females may be underdiagnosed due to better natural superficial social mimicry skills in females, partially different set of symptoms and less knowledge about autism in females among experts.[31] In his preword to the book Asperger's and Girls, Tony Attwood writes: "These tentative explanations for the apparent underrepresentation of girls with Asperger's Syndrome have yet to be examined by objective research studies."[32]

Specifically Judith Gould has discussed the idea that a pervasive developmental disorder called pathological demand avoidance, which is not officially included in diagnostic manuals may offer a glimpse about how autism in females may present in some cases.[33]

Autism and differences in gender and sexuality identification[edit]

Sexuality is often discussed within the autistic community, with many observations that identities other than cis-hetero seem to be more common than is observed in the neurotypical population. There have not been many formal studies on this to date, however members of the community speculate that autistic individuals generally have different ideals, perceptions and desires than neurotypicals or simply do not comprehend or agree with society's expectation, making them more apt to diverge from the norm.

Gender identity[edit]

A study looking at the co-occurrence of ASD in patients with gender dysphoria found 7.8% of patients to be on the autism spectrum.[34] This is much higher than the estimated 1% of people with ASD in the general population, suggesting a link between autism and gender variance.

As of yet, there have been no studies specifically addressing the occurrence of autism in intersex individuals.

Sexual satisfaction[edit]

A study conducted by Byers and Nichols (2014), explored the level of sexual satisfaction of high-functioning autistic individuals, with researchers testing the sexual and relationship satisfaction of neurotypical versus high functioning autistic individuals. The results suggest that men with ASD are generally less satisfied with their relationship or marriage compared to neurotypical men and women, and women with ASD.[35]

History[edit]

Hans Asperger was one of the first people to study autism, yet all of his four students were male. Another early researcher, Leo Kanner described "autistic disturbances of affective contact" in the group consisting of eight boys and three girls.[36]

See also[edit]

References[edit]

  1. ^ Fombonne, E. (2009). Epidemiology of pervasive developmental disorders. Pediatric Research, 65(6), 591–598. http://doi.org/10.1203/PDR.0b013e31819e7203
  2. ^ "Archived copy". Archived from the original on 2014-04-18. Retrieved 2016-07-11.CS1 maint: archived copy as title (link) Autism Spectrum Disorder (ASD): Data & Statistics
  3. ^ Begeer, S., Mandell, D., Wijnker-Holmes, B., Venderbosch, S., Rem, D., Stekelenburg, F., & Koot, H. M. (2013). Sex Differences in the Timing of Identification Among Children and Adults with Autism Spectrum Disorders. Journal of Autism and Developmental Disorders, 43, 1151–1156. http://doi.org/10.1007/s10803-012-1656-z
  4. ^ Gockley, J., Willsey, a J., Dong, S., Dougherty, J. D., Constantino, J. N., & Sanders, S. J. (2015). The female protective effect in autism spectrum disorder is not mediated by a single genetic locus. Molecular Autism, 6, 25. http://doi.org/10.1186/s13229-015-0014-3
  5. ^ Robinson, E. B., Lichtenstein, P., Anckarsater, H., Happe, F., & Ronald, a. (2013). Examining and interpreting the female protective effect against autistic behavior. Proceedings of the National Academy of Sciences, 110(13), 5258–5262. http://doi.org/10.1073/pnas.1211070110
  6. ^ a b Lai, M.-C., Baron-Cohen, S., & Buxbaum, J. D. (2015). Understanding autism in the light of sex/gender. Molecular Autism, 6, 1–6. http://doi.org/10.1186/s13229-015-0021-4
  7. ^ Baron-Cohen, S. (2002). The extreme male brain theory of autism. Trends in Cognitive Sciences, 6(6), 248–254. http://doi.org/10.1016/S1364-6613(02)01904-6
  8. ^ Lai, M.-C., Lombardo, M. V., Pasco, G., Ruigrok, A. N. V, Wheelwright, S. J., Sadek, S. a., … Baron-Cohen, S. (2011). A Behavioral Comparison of Male and Female Adults with High Functioning Autism Spectrum Conditions. PLoS ONE, 6(6), e20835. http://doi.org/10.1371/journal.pone.0020835
  9. ^ Lai, M.-C., Lombardo, M. V, Ruigrok, A. N. V, Chakrabarti, B., Wheelwright, S. J., Auyeung, B., … Baron-Cohen, S. (2012). Cognition in males and females with autism: similarities and differences. PLoS ONE, 7(10), e47198. http://doi.org/10.1371/journal.pone.0047198
  10. ^ a b Ludlow, a. K., Roberts, H., & Gutierrez, R. (2015). Social Anxiety and Response to Touch: A Preliminary Exploration of Broader Autism Phenotype in Females. SAGE Open, 5, 2158244015580854–. http://doi.org/10.1177/2158244015580854
  11. ^ Torres, E. B., Isenhower, R. W., Yanovich, P., Rehrig, G., Stigler, K., Nurnberger, J., & José, J. V. (2013). Strategies to develop putative biomarkers to characterize the female phenotype with autism spectrum disorders. Journal of Neurophysiology, 110, 1646–62. http://doi.org/10.1152/jn.00059.2013
  12. ^ Supekar, Kaustubh; Menon, Vinod (2015-09-04). "Sex differences in structural organization of motor systems and their dissociable links with repetitive/restricted behaviors in children with autism". Molecular Autism. 6 (1): 50. doi:10.1186/s13229-015-0042-z. PMC 4559968. PMID 26347127.
  13. ^ Holtmann, Martin; Bölte, Sven; Poustka, Fritz (2007). "Autism spectrum disorders: sex differences in autistic behaviour domains and coexisting psychopathology". Developmental Medicine & Child Neurology. 49 (5): 361–366. doi:10.1111/j.1469-8749.2007.00361.x. ISSN 1469-8749. PMID 17489810.
  14. ^ a b Baron-Cohen, Simon; Knickmeyer, Rebecca C.; Belmonte, Matthew K. (4 November 2005). "Sex differences in the brain: implications for explaining autism". Science. 310 (5749): 819–823. doi:10.1126/science.1115455. PMID 16272115. Pdf.
    Extracted in:
    Kessel, Cathy (15 November 2011). "Half of Women Do Not Have "Female Brains" (blog)". mathedck.wordpress.com. Mathematics and Education via WordPress.
  15. ^ a b Badcock, Christopher; Crespi, Bernard (June 2008). "Psychosis and autism as diametrical disorders of the social brain". Behavioral and Brain Sciences. 31 (3): 241–261. doi:10.1017/S0140525X08004214. ISSN 1469-1825.
  16. ^ a b Elliot, Michael; Stead, Philip; Crespi, Bernard (2010-01-26). "Comparative genomics of autism and schizophrenia". Proceedings of the National Academy of Sciences. 107 (suppl 1): 1736–1741. doi:10.1073/pnas.0906080106. ISSN 0027-8424. PMID 19955444.
  17. ^ a b Walter, Henrik; Freitag, Christine; Bara, Bruno G.; Weber, Bernhard; Poustka, Fritz; Hainz, Daniela; Schlitt, Sabine; Bölte, Sven; Ciaramidaro, Angela (2015-01-01). "Schizophrenia and Autism as Contrasting Minds: Neural Evidence for the Hypo-Hyper-Intentionality Hypothesis". Schizophrenia Bulletin. 41 (1): 171–179. doi:10.1093/schbul/sbu124. ISSN 0586-7614.
  18. ^ a b McGrath, John; Saha, Sukanta; Chant, David; Welham, Joy (2008). "Schizophrenia: A Concise Overview of Incidence, Prevalence, and Mortality" (PDF). Epidemiologic Reviews. 30: 67–76. doi:10.1093/epirev/mxn001. PMID 18480098.
  19. ^ a b Aleman; Kahn; Selten (2003). "Sex differences in the risk of schizophrenia: evidence from meta-analysis". Archives of General Psychiatry. 60 (6): 565–71. doi:10.1001/archpsyc.60.6.565. PMID 12796219 – via NCBI.
  20. ^ a b Abel, Kathryn; Drake, Richard; Goldstein, Jill (2010). "Sex differences in schizophrenia". International Review of Psychiatry. 22 (22(5)): 417–428. doi:10.3109/09540261.2010.515205. PMID 21047156 – via Ebsco.
  21. ^ Baron-Cohen, S., Jaffa, T., Davies, S., Auyeung, B., Allison, C., & Wheelwright, S. (2013). Do girls with anorexia nervosa have elevated autistic traits? Molecular Autism, 4(1), 24. http://doi.org/10.1186/2040-2392-4-24
  22. ^ Rhind, C., Bonfioli, E., Hibbs, R., Goddard, E., Macdonald, P., Gowers, S., … Treasure, J. (2014). An examination of autism spectrum traits in adolescents with anorexia nervosa and their parents. Molecular Autism, 5(1), 56. http://doi.org/10.1186/2040-2392-5-56
  23. ^ Cohen, Ira L.; Tsiouris, John A.; Flory, Michael J.; Kim, Soh-Yule; Freedland, Robert; Heaney, Glenn; Pettinger, Jill; Brown, W. Ted (May 2010). "A large scale study of the psychometric characteristics of the IBR Modified Overt Aggression Scale: findings and evidence for increased self-destructive behaviors in adult females with autism spectrum disorder". Journal of Autism and Developmental Disorders. 40 (5): 599–609. doi:10.1007/s10803-009-0908-z. ISSN 1573-3432. PMID 19941156.
  24. ^ "Eating disorder or disordered eating? Eating patterns in autism | Network Autism". network.autism.org.uk. Retrieved 2019-08-06.
  25. ^ Anderson, Jeffrey S.; et al. (May 2011). "Decreased interhemispheric functional connectivity in autism". Cerebral Cortex. 21 (5): 1134–1146. doi:10.1093/cercor/bhq190. PMC 3077433. PMID 20943668.
  26. ^ Teatero, Missy L.; Netley, Charles (November 2013). "A critical review of the research on the extreme male brain theory and digit ratio (2D:4D)". Journal of Autism and Developmental Disorders. 43 (11): 2664–2676. doi:10.1007/s10803-013-1819-6. PMID 23575643.
  27. ^ Baron-Cohen, Simon; Knickmeyer, Rebecca C.; Belmonte, Matthew K. (4 November 2005). "Sex differences in the brain: implications for explaining autism". Science. 310 (5749): 819–823. doi:10.1126/science.1115455. PMID 16272115. Pdf.
    Extracted in:
    Kessel, Cathy (15 November 2011). "Half of Women Do Not Have "Female Brains" (blog)". mathedck.wordpress.com. Mathematics and Education via WordPress.
  28. ^ Baron-Cohen, Simon (November 2012). "Autism and the technical mind: live chat with Simon Baron-Cohen, November 9, 10 A.M. EST". Scientific American. 307 (5). pp. 72–75.
  29. ^ Jacquemont, S., Coe, B., Hersch, M., Duyzend, M., Krumm, N., Bergmann, S., Beckmann, J., Rosenfeld, J., Eichler, E. (2014) A Higher Mutational Burden in Females Supports a “Female Protective Model” in Neurodevelopmental Disorders. The American Society of Human Genetics, http://www.cell.com/ajhg/abstract/S0002-9297(14)00059-7
  30. ^ "Gender and autism". The National Autistic Society. Retrieved 2016-06-01.
  31. ^ Attwood, Tony (2006). Asperger's and Girls. London: Jessica Kingsley Publishers. pp. 2–6. ISBN 978-1932565409.
  32. ^ Attwood, Tony (2006). Asperger's and Girls. London: Jessica Kingsley Publishers. p. 6. ISBN 978-1932565409.
  33. ^ "Missed Diagnosis or Misdiagnosis? Women and Girls with PDA" (PDF). Dr Judith Gould, Dr Jacqui Ashton Smith. Archived from the original (PDF) on 2016-10-13. Retrieved 2016-01-06.
  34. ^ De Vries, A. L. C., Noens, I. L. J., Cohen-Kettenis, P. T., van Berckelaer-Onnes, I. A., & Doreleijers, T. A. (2010). Autism Spectrum Disorders in Gender Dysphoric Children and Adolescents. J Autism Dev Disord, 40, 930–936. http://doi.org/10.1007/s10803-010-0935-9
  35. ^ Byers, E (2014). "Sexual Satisfaction of High-Functioning Adults with Autism Spectrum Disorder". Sexuality and Disability Sex.
  36. ^ Kanner, L. (1943). Autistic disturbances of affective contact. Nervous Child, 2, 217-250.