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