Antidepressant drugs have been found underused in the older population relative to younger adults, particularly in the USA before Medicare part D. No study assessed the antidepressant use according to age in France.

To compare the patterns of antidepressant use among young and older adults: treatment duration, switches, association of antidepressants, coprescription of psychotropic drugs and adherence to treatment.

A historical cohort study included 27,306 young adults and 7,747 older adults, who were beneficiaries of the French national health care insurance and initiated a new antidepressant treatment over the study period. They were followed for atleast six months.

Most patients received only one type of antidepressant (91.81% of young adults and 91.73% of older). The coprescription of psychotropic drugs was frequent in both groups (62.91% in young adults and 62.36% in older). The associations of antidepressant drugs were rare (1.42% in young adults and 1.50% in older). Elderly patients had a significantly longer duration of treatment than young adults (m = 135.4 days, SD = 198.6 vs m = 104.3 days, SD = 159.6; HR = 0.9; 95%CI=[0.88–0.93]; p < 0,0001). Furthermore, they had a higher probability of good adherence than young adults when treatment was initiated by a general practitioner (23.28% vs 16.02%; OR = 1.3 [1.22–1.41]), a hospital practitioner (OR = 1.76 [1.35–2.30]) or a specialist other than psychiatrist (OR = 1.85 [1.26–2.70]).

The use of antidepressant drugs was similar in both age groups, except for the treatment duration and adherence that were better in the older patients. This result may be attributed to the French healthcare system.