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

Verkes RJ, Kerkhof GA, Beld E, Hengeveld MW, van Kempen GMJ. Suicidality, circadian activity rhythms and platelet serotonergic measures in patients with recurrent suicidal behaviour. Acta Psychiatr Scand 1995: 93: 27–34. © Munksgaard 1995. 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.