Bipolar disorders (BP) with late onset are underestimated by their frequency, their misleading presentations and therapeutic difficulties due to the high prevalence of somatic comorbidities.

To identify sociodemographic, clinical and therapeutic characteristics in subjects with a late-onset BP.

Retrospective and comparative study of 101 patients followed for a BP (12 patients with BP started after 50 years and 89 patients with BP started earlier) from 2009 to 2015, in the department of psychiatry of the University Hospital Farhat Hached, Sousse, Tunisia.

The mean age of subjects with late-onset TBP was 46.11 ± 12.85 years. Women were in the majority (65.3%). Ten patients had a novo mania, four patients had a late-onset mania and one patient had a secondary mania. Regarding the socio-demographic data, only the regular professional activity was more reported in the elderly (P = 0.017). Regarding clinical data, BP type 1 and secondary mania were more reported in elderly with (P = 0.050 and P = 0.000 respectively). Elderly had significantly fewer depressive episodes (P = 0.026), fewer hypomanic episodes (P = 0.000). The durations of the latest episodes and the last intervals were shorter in elderly (P = 0.045 and P = 0.000). Concerning therapeutic data, elderly had fewer hospitalizations (P = 0.045), required lower mean doses of lithium (P = 0.04) and greater mean doses of tricyclic antidepressants (P = 0.047).

It is always necessary to look for an organic cause in manic syndrome in late-onset BP. Doses of lithium should be lower. However, doses of TAD should be higher.

The authors have not supplied their declaration of competing interest.