ABSTRACT
This chapter addresses the seemingly complicated issue of how bipolar disorder (BPD) can be genetically related to both schizophrenia and unipolar depression (UPD). The least controversial aspect of this question concerns the overlap between UPD and BPD which, until the publication of a family study independently in the same year, 1966, by Angst1 and Perris and D’Elia2 were usually lumped together. In Table 8.1 the family study results published over approximately the following 20 years are summarized. These show a fairly consistent pattern which is that, if the starting point is a proband or index case with bipolar disorder, there is an increase in the
Table 8.1 Affective disorder in first-degree relatives of bipolar and unipolar
probands (data from studies reviewed by McGuffin and Katz, 19863)
Relatives
Proband Number Age-corrected*
type of studies n at risk Bipolar Unipolar
Bipolar 12 3710 7.8 (1.5-17.9) —
3648 — 11.4 (0.5-22.4)
Unipolar 7 2319 0.6 (0.3-2.1) 9.1 (5.9-18.4)
Morbid risk† (range): %
frequency of both UPD and BPD among relatives, whereas in families ascertained via a UPD proband there was an excess only of UPD.
