Ks. Kendler et al., THE ROSCOMMON FAMILY STUDY .4. AFFECTIVE-ILLNESS, ANXIETY DISORDERS, AND ALCOHOLISM IN RELATIVES, Archives of general psychiatry, 50(12), 1993, pp. 952-960
Objectives: This report seeks to evaluate the specificity of the famil
ial liability to schizophrenia by examining in the relatives of the va
rious proband groups the risk for affective illness (AI), anxiety diso
rders, and alcoholism. Design: A case-controlled epidemiologic family
study using DSM-III-R criteria.Participants: Three hundred eighty-four
index probands from a psychiatric case register, 150 unselected contr
ol probands from an electoral register and 2043 of their living and tr
aceable relatives, of whom 1753 were personally interviewed. Results:
In personally interviewed relatives of schizophrenic probands, the lif
etime risk for all AI (24.9%+/-3.8%) or just bipolar AI (1.2%+/-0.7%)
was very similar to that found in interviewed relatives of controls (2
2.8%+/-4.0% and 1.4%+/-0.7%, respectively). However, the risk for all
AI (49.7%+/-12.9%) or bipolar AI (4.8%+/-3.2%) was substantially incre
ased in relatives of schizoaffective probands. A substantially higher
proportion of relatives of schizophrenic vs control probands who had A
I demonstrated psychotic-and specially mood-incongruent psychotic-symp
toms when affectively ill. Neither the risk for anxiety disorders nor
that for alcoholism was increased in relatives of schizophrenic vs con
trol probands. Conclusions: The familial liability to schizophrenia po
ssesses some specificity and does not substantially increase the risk
to AI, anxiety disorders, or alcoholism. Even when narrowly defined, s
chizoaffective disorder has a substantial familial link to classic AI.
The familial liability to schizophrenia predisposes to psychosis, and
especially mood-incongruent psychosis, when affectively ill. Finally,
these results do not support the hypothesis that, from a familial per
spective, schizophrenia and AI are on a single etiologic continuum.