Underlying cerebrovascular pathology in Subjective Cognitive Decline: A systematic review and meta‐analysis

Abstract

AbstractBackgroundSubjective cognitive decline (SCD) implies self‐reported cognitive complaints in absence of objective cognitive impairment. SCD has been postulated as an early marker of Alzheimer’s Disease (AD). However, longitudinal studies have linked SCD to future vascular dementia. Thus, we conducted a systematic review and meta‐analysis aiming to synthesise and analyse the available data on the association between SCD and the presence of underlying cerebrovascular pathology measured by MRI.MethodOur study was performed following the PRISMA statement. The search strategy included terms for “subjective cognitive decline” and “white matter signal abnormalities”. It was conducted in 3 databases (PubMed, Scopus and Web of Science) from origin by December 8th, 2021. Two authors screened the studies in a 2‐stepwise approach. Primary studies including cognitively unimpaired adults with subjective cognitive complaints meeting the SCD‐I criteria for SCD that evaluated cerebrovascular pathology based on white matter signal abnormalities (WMSA) on MR images were selected. Study quality was assessed using the FLC 3.0 tool. Meta‐analysis comparing case‐control mean difference of WMSA was performed.ResultOf 240 articles identified, 16 research articles were selected. Of those, 8 case‐control studies were selected for the meta‐analysis. The sample size of the SCD group across the studies ranged from 8 to 906 participants, with age ranged from 40 to 84 years. All eight studies comprised a total of 2.637 SCD individuals. Study quality was deemed moderate (n=6) to high (n=10). The meta‐analysis showed a significant overall effect‐size between the mean WMSA burden of SCD and the controls, that was not significantly heterogeneous (Q(gl=7)=14.20; p=0,04; I2=42,5%). SCD was significantly associated with higher CVP burden based on neuroimaging measures.ConclusionThis is the first study to synthesise and analyse the current evidence on the association between SCD and WMSA. Our findings show the usefulness of SCD as a marker of underlying cerebrovascular pathology. Thus, the potential role of SCD as a preclinical stage of vascular cognitive impairment needs further investigation. Changes in lifestyle (e.g. exercise, diet, smoking cessation), cognitive stimulation or pharmacotherapy may be key to avoid an evolution towards cognitive deterioration in SCD.