The varying burden of depressive symptoms across adulthood: Results from six NHANES cohorts

Abstract

Background: Depressive symptoms differ from each other in the degree of functional impairment they cause. The incidence of depression varies across the adult lifespan. We examined whether age moderates the impairment caused by depressive symptoms.

Methods: The study sample (n = 21,056) was adults drawn from six multistage probability samples from the National Health and Nutrition Examination Survey series (NHANES, years 2005-2016) conducted in the United States using cross-sectional, representative cohorts. Depressive symptoms were assessed with the nine-item Patient Health Questionnaire (PHQ-9). We used regression models to predict high functional impairment, while controlling for sociodemographic variables and physical disorders.

Results: Age moderated the association between depressive symptoms and functional impairment: middle-aged adults perceived moderate and severe symptoms as more impairing than did others. Older adults reported slightly higher impairment due to mild symptoms. The individual symptoms of low mood, feelings of worthlessness and guilt, and concentration difficulties were more strongly related to high impairment in mid-adulthood as compared to early and late adulthood.

Limitations: Cross-sectional data allows only between-person comparisons. The PHQ-9 is brief and joins compound symptoms into single items. There was no information available concerning comorbid mental disorders. Co-occurring physical disorders were self-reported.

Conclusions: Symptoms of depression may imply varying levels of impairment at different ages. The results suggest a need for age adjustments when estimating the functional impact of depression in the general population. Additionally, they show a need for more accurate assessments of depression-related impairment at older ages. Evidence-based programs may generally benefit from symptom- and age-specific findings.

Keywords: Adulthood; Cross-sectional; Depression; Functional impairment; Symptom analysis.