Delirium symptoms are associated with decline in cognitive function between ages 53 and 69 years: Findings from a British birth cohort study

INTRODUCTION: Few population studies have investigated whether longitudinal decline after delirium in mid-to-late life might affect specific cognitive domains. METHODS: Participants from a birth cohort completing assessments of search speed, verbal memory, and the Addenbrooke's Cognitive Examination at age 69 were asked about delirium symptoms between ages 60 and 69 years. Linear regression models estimated associations between delirium symptoms and cognitive outcomes. RESULTS: Period prevalence of delirium between 60 and 69 years was 4% (95% confidence interval 3.2%–4.9%). Self-reported symptoms of delirium over the seventh decade were associated with worse scores in the Addenbrooke's Cognitive Examination (−1.7 points; 95% confidence interval −3.2, −0.1; P = .04). In association with delirium symptoms, verbal memory scores were initially lower, with subsequent decline in search speed by the age of 69 years. These effects were independent of other Alzheimer's risk factors. DISCUSSION: Delirium symptoms may be common even at relatively younger ages, and their presence may herald cognitive decline, particularly in search speed, over this time period.