The adoption into the UK of children who have been reared in severely deprived conditions provides an opportunity to study possible association between very early negative experiences and subsequent brain development. This cross-sectional study was a pilot for a planned larger study quantifying the effects of early deprivation on later brain structure. We used magnetic resonance imaging (MRI) to measure the sizes of three key brain regions hypothesized to be sensitive to early adverse experiences. Our sample was a group of adoptee adolescents (N = 14) who had experienced severe early institutional deprivation in Romania and a group of non-institutionalised controls (N = 11). The total grey and white matter volumes were significantly smaller in the institutionalised group compared with a group of non-deprived, non-adopted UK controls. After correcting for difference in brain volume, the institutionalised group had greater amygdala volumes, especially on the right, but no differences were observed in hippocampal volume or corpus callosum mid-sagittal area. The left amygdala volume was also related to the time spent in institutions, with those experiencing longer periods of deprivation having a smaller left amygdala volume. These pilot findings highlight the need for future studies to confirm the sensitivity of the amygdala to early deprivation.

Disinhibited attachment constitutes a valid, and handicapping, clinical pattern that is strongly associated with an institutional rearing.

Cognitive outcomes at age 11 of 131 Romanian adoptees from institutions were compared with 50 U.K. adopted children. Key findings were of both continuity and change: (1) marked adverse effects persisted at age 11 for many of the children who were over 6 months on arrival; (2) there was some catch-up between ages 6 and 11 for the bottom 15%; (3) there was a decrease of 15 points for those over 6 months on arrival, but no differentiation within the 6-42-month range; (4) there was marked heterogeneity of outcome but this was not associated with the educational background of the adoptive families. The findings draw attention to the psychological as well as physical risks of institutional deprivation.

IMPORTANCE Most evidence to date highlights the importance of genetic influences on the liability to autism and related traits. However, most of these findings are derived from clinically ascertained samples, possibly missing individuals with subtler manifestations, and obtained estimates may not be representative of the population. OBJECTIVES To establish the relative contributions of genetic and environmental factors in liability to autism spectrum disorder (ASD) and a broader autism phenotype in a large population-based twin sample and to ascertain the genetic/environmental relationship between dimensional trait measures and categorical diagnostic constructs of ASD. DESIGN, SETTING, AND PARTICIPANTS We used data from the population-based cohort Twins Early Development Study, which included all twin pairs born in England and Wales from January 1, 1994, through December 31, 1996. We performed joint continuous-ordinal liability threshold model fitting using the full information maximum likelihood method to estimate genetic and environmental parameters of covariance. Twin pairs underwent the following assessments: the Childhood Autism Spectrum Test (CAST) (6423 pairs; mean age, 7.9 years), the Development and Well-being Assessment (DAWBA) (359 pairs; mean age, 10.3 years), the Autism Diagnostic Observation Schedule (ADOS) (203 pairs; mean age, 13.2 years), the Autism Diagnostic Interview–Revised (ADI-R) (205 pairs; mean age, 13.2 years), and a best-estimate diagnosis (207 pairs). MAIN OUTCOMES AND MEASURES Participants underwent screening using a population-based measure of autistic traits (CAST assessment), structured diagnostic assessments (DAWBA, ADI-R, and ADOS), and a best-estimate diagnosis. RESULTS On all ASD measures, correlations among monozygotic twins (range, 0.77-0.99) were significantly higher than those for dizygotic twins (range, 0.22-0.65), giving heritability estimates of 56% to 95%. The covariance of CAST and ASD diagnostic status (DAWBA, ADOS and best-estimate diagnosis) was largely explained by additive genetic factors (76%-95%). For the ADI-R only, shared environmental influences were significant (30% [95% CI, 8%-47%]) but smaller than genetic influences (56% [95% CI, 37%-82%]). CONCLUSIONS AND RELEVANCE The liability to ASD and a more broadly defined high-level autism trait phenotype in this large population-based twin sample derives primarily from additive genetic and, to a lesser extent, nonshared environmental effects. The largely consistent results across different diagnostic tools suggest that the results are generalizable across multiple measures and assessment methods. Genetic factors underpinning individual differences in autismlike traits show considerable overlap with genetic influences on diagnosed ASD.

IQ, EF and anxiety appear to be implicated in the processes by which certain autistic young people can compensate for their underlying ToM difficulties. This tendency to compensate does not appear to reflect the severity of 'hit' for ASD per se, suggesting that well-compensated individuals are not experiencing a milder form of ASD. The construct of compensation in ASD has implications for research and clinical practice.