Prevalence of Depressive Symptoms in the Whole Spectrum of Cognitive Aging: Findings from the HELIAD Community Study

Background Depressive symptoms embody a risk factor for developing age‐related cognitive impairment, while they belong to the most common non‐cognitive symptoms of dementia. The conundrum of the prevalence of depressive symptoms in older adults in the Mediterranean region, but also worldwide is vividly reflected in reported prevalence rates ranging from 7.7% in a study from Malaysia and Australia to 81.1% in India. The present study aimed to shed light on the prevalence of mild, moderate and severe depressive symptoms in the entire spectrum of cognitive aging based on a cohort of randomly selected older adults from municipal rosters of two locations in Attica and central Greece. Methods Based on a thorough neurological and neuropsychological assessment, the diagnoses of mild cognitive impairment, Alzheimer’s dementia (AD) or dementia caused by other diseases (non‐AD) were established in participants of the Hellenic Epidemiological Longitudinal Investigation of Aging and Diet (HELIAD). The presence of depressive symptoms was tapped with the 15‐item Geriatric Depression Scale (GDS). Scores between 0‐4 point to the absence of depression, while scores between 5‐8, 9‐11, 12‐15 are compatible with mild, moderate and severe depressive symptoms, respectively. Statistical analyses were based on Pearson’s Chi‐squared test and pairwise proportions tests. Results The prevalence of depressive symptoms in the total sample (n = 1937 participants; mean age 73,84 SD: 5,427, females: 1148) was 19.5% (mild 13.1%, moderate 3.8%, severe 2.5%). The prevalence of depressive symptoms in older adults without cognitive impairment was 18%, in patients with MCI 27%, in AD 25% and in non‐AD 23.5%. The differences in the distribution of depressive symptoms of different severity across the four groups reached statistical significance (chi‐squared = 28.957, df = 9, p‐value