Six-year clinical course of depressive and anxiety disorders: analysis by age

Evidence on the association between age and the long-term course of affective disorders remains mixed.

This study examined the 6-year symptom and diagnostic trajectories of depression and anxiety in relation to age, and assessed whether social, lifestyle, somatic and clinical factors explained observed age-related differences.

A cohort of 1701 participants aged 18-65 years with a current depressive and/or anxiety disorder from the Netherlands Study of Depression and Anxiety were assessed biennially over 6 years. Clinical diagnoses were ascertained using the Composite International Diagnostic Interview, while symptom severities were measured with the Inventory of Depressive Symptomatology, Beck Anxiety Inventory, Fear Questionnaire and Penn State Worry Questionnaire. Linear mixed-effects models examined age differences in symptom changes over time; multinomial logistic regression examined age differences in diagnostic course. Models were sequentially adjusted for social, lifestyle, somatic and clinical factors to explain observed age-related differences.

Over the 6-year follow-up, older age was associated with slower improvement in depressive (b_{per 10 years}=0.191 (0.103 to 0.279)) and anxiety symptoms (b_{per 10 years}=0.119 (0.048 to 0.191)), but not for fear or worry. Older age was associated with a higher likelihood of a chronic course versus early remission (RRR_{per 10 years}=1.19 (1.05 to 1.36)), primarily driven by depression chronicity. Age-related differences in symptom trajectories persisted across all adjusted models, while associations with depression diagnostic chronicity were attenuated after adjustment for social and lifestyle factors.

Higher chronological age is an independent risk factor for a less favourable long-term course of affective disorders, particularly depression, characterised by slower symptom improvement and increased chronicity.

Age-tailored depression management, including closer follow-up and timely treatment optimisation, may help improve clinical course in later life.