Amyloid Plaques and Symptoms of Depression Links to Medical Help-Seeking due to Subjective Cognitive Decline

Abstract

Background: Subjective cognitive decline (SCD) is associated with an increased risk of Alzheimer's disease (AD). However, patients reporting SCD to their general practitioner are not always referred to a memory clinic. Objective: To investigate whether prior history of medical help-seeking is associated with AD biomarker abnormality, worse cognitive performance, and/or depressive symptoms in SCD. Methods: We compared levels of cerebrospinal fluid (CSF) Aβ1 - 42, cognitive performance, and depressive symptoms (15-item Geriatric Depression Scale, GDS-15) between healthy controls (n = 88), SCD with a history of medical help seeking (SCD-HS, n = 67), and SCD non help-seekers (SCD-NHS, n = 44). Cases with evidence of amyloid plaques (CSF Aβ1 - 42 ≤708 ng/l) and symptoms of depression (GDS-15≥6) were determined in both SCD groups. Results: The SCD-HS group had lower CSF Aβ1 - 42 (p < 0.01), lower word list learning and memory recall (p < 0.0001), and an increased level of depressive symptoms (p < 0.0001) compared to controls and SCD-NHS cases. The SCD-HS group had more cases with symptoms of depression (n = 12, 18%) and amyloid plaques (n = 18, 27%) compared to SCD-NHS (n = 1, 2% and n = 7, 16%, respectively). None of the SCD-HS cases and only one SCD-NHS case had concurrent symptoms of depression and amyloid plaques. The SCD-HS cases showed equal word list learning and memory performance regardless of amyloid status or symptoms of depression. Conclusion: Medical help-seeking in SCD is associated with an increased risk of AD pathology or symptoms of depression. However, subtle memory deficits are seen in SCD help-seekers, also without amyloid plaques or symptoms of depression.