Psychotic and Neurotic Illnesses in Twins

Congenital risk factors for schizophrenia

“…Sadly, those who acknowledged Rosanoffs findings were dismissive. In a review of the area, Slater (1953) concluded, 'There is no evidence that (early brain injuries) play a significant role in schizophrenia'.…”

Mongolism in Twin Sibships

“…A difference of more than five in the twins' total score is strongly indicative of dizygosity. The same diagnostic significance applies to scores over two obtained with Slater's discriminant function [13]-the m ost complex test devised. A Sluter score below minus one is usually indicative of monozygosity.…”

An Analysis of Family Data on 1000 Patients Admitted to a Canadian Mental Hospital

“…Penrose, 1950;Slater, 1950Slater, , 1953Sjogren, 1957) have been more cautious in their interpretations of the facts, and tend to regard each of the functional psychoses, and other personality disorders based on clinical diagnoses, as more or less heterogene ous m aterial, which m ay include types inherited by various different genetic m echanisms and also types not genetically conditioned. Slater (1950) com m ents on the likelihood th a t there are aetiological factors, and probably genetical ones, which affect both intelligence and personality.…”

“…However, it has not always been recognized th at such tw in studies are open to a num ber of serious scientific difficulties and objections (e.g. Neel and Schull, 1954;Slater. 1953;Walker and Reid, 1955).…”