Suicidality, circadian activity rhythms and platelet serotonergic measures in patients with recurrent suicidal...

The circadian activity rhythm was assessed over a one-week period using a wrist-worn activity monitor in 59 patients with a history of recurrent suicide attempts. In 40 of these patients a second recording was made 6 months later. Platelet serotonin (5-HT) and monoamine oxidase-B activity (MAO) were measured. Suicidal ideation, borderline personality disorder and impulsiveness were associated with the absence of a clear 24-hour periodicity in motor activity. Depressive mood and hopelessness were associated with a less regular bed-in time and a lower daytime activity. Platelet 5-HT as well as MAO correlated negatively with the amplitude of the circadian activity rhythm. Our results support the suggested link between suicidality, altered circadian activity and serotonergic function.