Family history of psychiatric disorders and the outcome of psychiatric patients with DSM-IV major depressive disorder

Major Depressive Disorder (MDD) is often comorbid with other heritable disorders. The correlates of a family history (FH) of mood disorders but not of comorbid disorders among MDD patients have been investigated. Since bipolar disorder (BD) is highly heritable, latent BD may bias findings.The Vantaa Depression Study included 269 psychiatric out- and in-patients with DSM-IV MDD, diagnosed with semistructured interviews and followed-up for 5 years with a life-chart. The FH of mood, psychotic disorders, and alcoholism among first-degree relatives of 183 patients was investigated.Three fourths (74.9%) of patients reported a FH of some major mental disorder; 60.7% of mood disorder, 36.6% alcoholism, and 10.9% psychotic disorder. In multivariate regression models, a FH of mood disorder was associated with high neuroticism (OR 1.08 [1.02-1.15], p=0.014); a FH of alcoholism with alcohol dependence, number of cluster B personality disorder symptoms, and dysthymia (OR 2.27 [1.01-5.08], p=0.047; OR=1.11 [1.01-1.23], p=0.030; and OR 4.35 [1.51-12.5], p=0.007), and a FH of psychotic disorder with more time spent with depressive symptoms (OR 1.03 [1.00-1.05], p=0.043). However, after excluding those who later switched to BD, several of the associations abated or lost significance.Family history was ascertained only by an interview of the proband.The majority of MDD patients have a positive FH besides mood also of other disorders. A mood disorder FH may correlate with higher neuroticism, alcoholism FH with alcoholism or personality disorders. FH studies of MDD should take into account the impact of patients switching to BD.