Adoption studies

Most children inherit their genes and their family culture from the same set of parents. However, since adoptees do not, adoption studies offer the opportunity of separating the effects of the two. In the first study of schizophrenia, Heston and Denney (2) demonstrated that five out of 47 children of schizophrenic mothers who were adopted away within a few days of their birth, later developed schizophrenia compared with none out of 50 adoptees with no family history of schizophrenia. Similar findings were reported from the Danish-American Study of Rosenthal et al.(3) who found that a significantly higher proportion of the adopted-away offspring of schizophrenic parents from Copenhagen were classified as having schizophrenia or 'borderline schizophrenia', than were control adoptees. This study originated the concept of the schizophrenia spectrum disorder, which has come to include not only frank schizophrenia but also schizophreniform disorder, as well as schizotypal and possibly paranoid personality disorder.

In an extension of the Danish-American collaboration, Kety et al.(4) took all schizophrenic adoptees in Denmark as their starting point, and then examined their biological and adoptive relatives; unlike the earlier adoption studies this one also used operational definitions of the schizophrenia spectrum conditions. Fully 23.5 per cent of the biological first-degree relatives of schizophrenic adoptees received a schizophrenia spectrum diagnosis compared with only 4.7 per cent of the biological relatives of normal control adoptees; the adoptive relatives of both groups of adoptees had very low rates of spectrum disorders.

Finally, Wender et al.(5) studied the grown-up children of normal individuals who, by mischance, had been placed with an adoptive parent who later developed schizophrenia. Thankfully, these unfortunate adoptees did not themselves show an increased risk of the disorder. Thus, adoption studies consistently indicate that the familial aggregation of schizophrenia is determined by individuals inheriting genes from someone with the disorder (or a related spectrum condition) rather than any effect of the intrafamilial culture (e.g. being brought up by a parent with schizophrenia).

Funny Wiring Autism

Funny Wiring Autism

Autism is a developmental disorder that manifests itself in early childhood and affects the functioning of the brain, primarily in the areas of social interaction and communication. Children with autism look like other children but do not play or behave like other children. They must struggle daily to cope and connect with the world around them.

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