Recent Birth Cohorts May Have More Depression and Bipolar Disorder
In medicine, the ‘cohort effect’ describes the idea that more recent birth cohorts have an increased incidence and younger age of onset of their illness. A 2016 article by this editor (Robert M. Post) and colleagues in the Journal of Clinical Psychiatry presented evidence that younger patients with bipolar disorder have an earlier age of onset of bipolar disorder and more relatives with mood disorders than older patients with bipolar disorder.
The research was carried out by the Bipolar Collaborative Network in four US cities (Dallas, Cincinatti, Los Angeles, and Bethesda) and three northern European ones (Utrecht, Freiburg, and Munich). On both continents, patients born more recently had an earlier age of onset of their bipolar disorder. Younger patients also had parents and grandparents with a greater incidence of depression, bipolar disorder, and alcohol and substance abuse compared to older patients.
Editor’s Note: Other researchers have found evidence of a cohort effect for unipolar depression, substance abuse, and attention-deficit hyperactivity disorder (ADHD). The data indicate that childhood onset of psychiatric illnesses may be becoming more common. Research aimed at earlier detection and treatment is needed to reverse these trends.