Subgroups with typical courses of depressive symptoms in an elderly population during 13 years of observation: Results from the Heinz Nixdorf Recall Study

Background: Depressive symptoms are volatile over time but empirical studies of intra-individual variations of depressive symptoms over longer periods are sparse. Aims: We aim to examine fluctuation patterns of depressive symptoms and to investigate the possible influence of age, sex and socioeconomic factors on fluctuation in a population-based sample over a period of 13 years. Methods: We used data of 4,251 participants (45-75 years; 51.0% women at baseline) of the Heinz Nixdorf Recall Study with at least two of nine possible measurements obtained in the period between 2000 and 2017. Depressive symptoms were assessed via the Center for Epidemiologic Studies Depression Scale (CES-D) short form. Based on the individual mean values and standard deviation from all measurements, we categorized participants as G1 'stable low', G2 'stable high', G3 'stable around cutoff' and G4 'large fluctuations'. Results: Most participants (82.3%) showed stable low depressive symptoms (G1), whereas 2.3% performed stable high values (G2), 6.9% stable around the cutoff (G3) and 8.6% large fluctuations (G4). Conclusion: Our longitudinal results reveal that almost 18% (G2, G3 and G4) of the participants have an increased depression score or strong fluctuations at times. According to our classification, a higher proportion of the participants show anomalies with regard to depression compared to a simple classification into depressed and nondepressed, especially if this is based on a single measurement. Thus, longitudinal measurements of depression can prevent misclassification and provide valuable information about the course of depressive symptoms for a better understanding of the changes of depression.