Familial variation in episode frequency in bipolar affective disorder.
OBJECTIVE
Bipolar affective disorder is a familial illness characterized by recurrent episodes of mania and depression, but little is known about the familial nature of episode recurrence or its associated clinical features. The authors analyzed the recurrence frequency of affective episodes (episode frequency), along with associated clinical and demographic variables, in families with at least three members with a major affective disorder.


METHODS
Members of 86 families ascertained through probands with bipolar affective disorder who had two or more first-degree relatives with a major affective disorder were interviewed by psychiatrists and assigned an all-sources diagnosis. Data for 407 subjects with a major affective disorder were analyzed. Episode frequency was estimated as the number of episodes of major depression, mania, and hypomania per year of illness.


RESULTS
Episode frequency was smoothly distributed over the range of 0.02-20.2 episodes/year. Episode frequency was significantly correlated among relatives (r=0.56, p<0.004). Earlier age at onset, bipolar II disorder, hallucinations or delusions, alcoholism, and suicidal behavior were all more prevalent in the highest than in the lowest quartiles of episode frequency. Female gender and recurrent major depression were more prevalent in the lowest quartile. Panic disorder, substance abuse, and thyroid disease were all unrelated to episode frequency. Subjects with DSM-IV rapid cycling did not differ from other affected subjects for most of the variables tested.


CONCLUSIONS
Episode frequency is a highly familial trait in bipolar affective disorder, associated with several indicators of severity, and may be useful in defining clinical subtypes of bipolar affective disorder with greater genetic liability. DSM-IV rapid cycling was not supported by these data as the best predictor of familiality or severity.
Fisfalen
Maria E
ME
Department of Psychiatry, Mount Sinai Medical Center, Rosalind Franklin University of Medicine and Science, California at 15th Street, Chicago, IL 60608, USA. fism@sinai.org
Schulze
Thomas G
TG
DePaulo
J Raymond
JR
DeGroot
Leslie J
LJ
Badner
Judith A
JA
McMahon
Francis J
FJ
D000328:Adult; D017668:Age of Onset; D001714:Bipolar Disorder / Q000175:diagnosis* / Q000235:genetics* / Q000523:psychology; D003865:Major Depressive Disorder / Q000175:diagnosis / Q000235:genetics / Q000523:psychology; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005260:Female; D020022:Genetic Predisposition to Disease / Q000235:genetics; D014644:Genetic Variation; D006801:Humans; D008297:Male; D010375:Pedigree; D011569:Psychiatric Status Rating Scales; D011618:Psychotic Disorders / Q000175:diagnosis / Q000235:genetics / Q000523:psychology; D012008:Recurrence; D012720:Severity of Illness Index; D012737:Sex Factors