From Subjective Cognitive Decline to Alzheimer’s Disease: The Predictive Role of Neuropsychological Assessment, Personality Traits, and Cognitive Reserve. A 7-Year Follow-Up Study

Abstract

The aim of this study was to evaluate the accuracy of neuropsychological assessment in predicting conversion from subjective cognitive decline (SCD) and mild cognitive impairment (MCI) to Alzheimer's disease (AD) and the effect of personality traits and cognitive reserve in progression from SCD to MCI. As part of a longitudinal, clinical-neuropsychological-genetic survey on SCD and MCI, 284 patients referred to our hospital between 1990 and 2017 were included. All patients underwent clinical-extensive neuropsychological evaluation and Apolipoprotein E genotyping; personality traits were assessed in a subgroup. Each patient underwent clinical-neuropsychological follow-up. Subjects with a follow-up shorter than two years were excluded. A total of 212 subjects were, after exclusions, considered: 26 out of 109 SCD subjects progressed to MCI (SCD-p), 15 converted to AD (SCD-c), and 68 remained stable (SCD-s). Of 103 MCI subjects, 39 converted to AD (MCI-c) and 64 remained stable (MCI-s). At baseline, SCD-c performed significantly worse than SCD-s in tests assessing long-term verbal memory. MCI-c showed worse performance on neuropsychological tests for short- and long-term verbal memory and for ecological evaluation of memory (RBMT). These tests provided good accuracy in distinguishing MCI-c and MCI-s. Emotional stability was significantly lower in SCD-s than in SCD-p while higher intellectual activities were associated with a lower risk of conversion to MCI. Our results suggest that memory neuropsychological tests may represent a reliable tool to estimate the risk of progression to AD. Personality and lifestyle factors could provide useful information to identify SCD subjects who may develop an objective cognitive impairment.

Neuroimaging advances regarding subjective cognitive decline in preclinical Alzheimer’s disease

“…Only a few longitudinal studies of people with carefully phenotyped SCD have investigated the rate of progression of SCD to dementia due to AD [ 13 , 14 ]. With clinical advances, the increasing number of memory clinics will facilitate the enrollment of subjects with SCD and increase awareness about SCD and the concept of cognitive protection.…”

Questions concerning the role of amyloid-β in the definition, aetiology and diagnosis of Alzheimer’s disease

“…The advent of genetics and imaging has taken some emphasis away from the critical need to focus on developing better detailed methods to understand normal cognition, cognitive decline and the myriad of other issues occurring alongside AD and dementia more broadly. There are clearly limitations to cognitive testing regimens for dementia [ 102 , 104 , 206 ], indicating more sophisticated neuropsychological assessments are required to better predict and define cognitive and other changes [ 21 , 102 , 217 ], particularly in preclinical stages of disease [ 182 ]. This would likely have a profound impact on predictive power [ 199 ].…”

Association of lifespan cognitive reserve indicator with the risk of mild cognitive impairment and its progression to dementia

“…Mild cognitive impairment (MCI) is an intermediate condition between normal cognition and dementia and is associated with an increased risk of dementia 6 . Previous studies have indicated that high education, 7 and social, cognitive, or intellectual activity 8‐10 might be related to decreased incidence of MCI among cognitively intact individuals. So far, no studies have examined the association of lifespan CR indicator with the risk of MCI.…”