Table 1

Life-time risk of affective disorder in relatives of a person with bipolar disorder. The approximate life-time risk of bipolar disorder and the additional life-time risk of unipolar depression are shown according to degree of the biological relationship to the proband. These figures represent estimates taken from studies conducted over the past 30 years that have used the modern concept of bipolar disorder (Craddock, 1995)

Life-time risk of bipolar disorder (%) Life-time risk of unipolar disorder (%)
Monozygotic co-twin 45-75 15-25
First-degree relative 4-9 8-20
Unrelated 0.5-1.5 5-10