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544[evol-psych] Autism, criminality and sex chromosomes

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  • Ian Pitchford
    Sep 1 12:00 AM
      From the current issue of Psychological Medicine

      Psychological Medicine (1999), 29:769-786. Cambridge University Press.

      The epidemiology of autism: a review
      ERIC FOMBONNE a1 c1

      a1From the MRC Child Psychiatry Unit, Institute of Psychiatry, London


      Background. There is some uncertainty about the rate and correlates of autism.

      Method. Twenty-three epidemiological surveys of autism published in the English
      language between 1966 and 1998 were reviewed.

      Results. Over 4 million subjects were surveyed; 1533 subjects with autism were
      identified. The methodological characteristics of each study are summarized,
      including case definition, case-finding procedures, participation rates and
      precision achieved. Across surveys, the median prevalence estimate was
      5·2/10000. Half the surveys had 95% confidence intervals consistent with
      population estimates of 5·4-5·5/10000. Prevalence rates significantly increased
      with publication year, reflecting changes in case definition and improved
      recognition; the median rate was 7·2/10000 for 11 surveys conducted since 1989.
      The average male/female ratio was 3·8[ratio]1, varying according to the absence
      or presence of mental retardation. Intellectual functioning within the normal
      range was reported in about 20% of subjects. On average, medical conditions of
      potential causal significance were found in 6% of subjects with autism, with
      tuberous sclerosis having a consistently strong association with autism. Social
      class and immigrant status did not appear to be associated with autism. There
      was no evidence for a secular increase in the incidence of autism. In eight
      surveys, rates for other forms of pervasive developmental disorders were two to
      three times higher than the rate for autism.

      Conclusion. Based on recent surveys, a minimum estimate of 18·7/10000 for all
      forms of pervasive developmental disorders was derived, which outlines the
      needs in special services for a large group of children.

      c1Address for correspondence: Dr Eric Fombonne, MRC Child Psychiatry Unit,
      Institute of Psychiatry, De Crespigny Park, Denmark Hill, London SE5 8AF.


      Psychological Medicine (1999), 29:953-962. Cambridge University Press.

      Criminality and antisocial behaviour in unselected men with sex chromosome

      M. J. GÖTZ a1 c1, E. C. JOHNSTONE a1 and S. G. RATCLIFFE a1
      a1From the Department of Psychiatry, Royal Edinburgh Hospital, Edinburgh; and
      Institute of Child Health, London


      Background. Previous studies on male patients with sex chromosome abnormalities
      (SCA), namely XYY and XXY, suggest that such patients commit criminal acts more
      frequently than expected. Most of these studies are affected by ascertainment

      Methods. Using a population-based sample of men with SCA, identified by
      screening 34380 infants at birth between 1967 and 1979, comparison between 16
      XYY men, 13 XXY men and 45 controls were made in terms of frequency of
      antisocial personality disorder (APD) using the Schedule for Affective
      Disorders and Schizophrenia lifetime version. Rates of criminal convictions
      were examined in 17 XYY men, 17 XXY men and 60 controls.

      Results. XYY males showed a significantly higher frequency of antisocial
      behaviour in adolescence and adulthood and of criminal convictions than the
      controls, but multiple regression analysis showed this to be mediated mainly
      through lowered intelligence. Property offences constituted the majority of
      offences in all groups. The XXY men did not show an increased rate of criminal
      convictions. It is possible that this apparently negative result relates to the
      relatively small numbers of cases and hence low power of this study.

      Conclusions. The findings of this study carry the advantage of not being
      affected by ascertainment bias and the disadvantage of having low power. It
      provides evidence for a slightly increased liability to antisocial behaviour in
      XYY men.

      c1Address for correspondence: Dr Michael J. Götz, Kildean Day Hospital, Drip
      Road, Stirling FK5 1RN.

      Ian Pitchford <Ian.Pitchford@...>
      Centre for Psychotherapeutic Studies
      School for Health and Related Research
      University of Sheffield, S10 2TA, UK