Temporal Relationship Between Depressive Symptoms and Cognition in Mid and Late Life: A Longitudinal Cohort Study

ObjectivesTo examine the bidirectional temporal relationship between depressive symptoms and cognition in relation to risk, reaction, and prodrome.DesignCross-lag analysis of longitudinal data collected online at baseline and 12-month follow-up.Setting and ParticipantsA United Kingdom population cohort of 11,855 participants aged 50 years and over.MeasuresPatient Health Questionnaire-9 (depressive symptoms), cognitive measures: Paired Associate Learning, Verbal Reasoning, Spatial Working Memory, and Digit Span.ResultsDepressive symptoms predicted a decline in paired associates learning β = ?.020, P = .013, (95% confidence interval CI], ?.036, ?.004)] and verbal reasoning β = ?.014, P = .016, (95% CI ?.025, ?.003)] but not vice versa. Depressive symptoms predicted β = ?.043, P < .001, (95% CI ?.060, ?.026); β = ?.029, P < .001, (95% CI ?.043, ?.015)] and were predicted by β = ?.030, P = < .001, (95% CI ?.047, ?.014); β = ?.025, P = .003, (95% CI ?.041, ?.009)], a decline in spatial working memory and verbal digit span, respectively.Conclusions and ImplicationsDepressive symptoms may be either a risk factor or prodrome for cognitive decline. In addition, a decline in attention predicts depressive symptoms. Clinical implications and implications for further research are discussed.