How "Subjective" is Subjective Cognitive Decline?

Abstract

Subjective cognitive decline is presently considered to be the earliest clinical stage of neurodegeneration. By its current definition, subjective cognitive decline conceptually implies that the sufferer presents no psychometrically measurable cognitive impairment despite numerous articles stating the presence of discrete objective impairments. Our purpose was to evaluate differences in objective cognitive performance in subjective cognitive decline patients compared to healthy controls. A total of 101 cognitively unimpaired participants were divided into a subjective cognitive decline group (n = 67) and healthy control group (n = 34). We conducted a thorough cognitive evaluation and collected social, demographic, and clinical data as well as data on personality traits, sleep quality, and physical activity. Both groups were matched for sex, age, education, and Mini-Mental State Examination score. The subjective cognitive decline group had a lower verbal learning capacity as shown by the worse performance on Rey auditory verbal learning test trial 1 (P = .021) and Rey auditory verbal learning test total scores (P = .023). The subjective cognitive decline group was significantly more impaired in executive functioning compared to controls, as shown by trail making test A (P = .012) evaluation. Persons with subjective cognitive decline have subtle, objective cognitive impairments which may be undetected with widely used, brief cognitive evaluations, such as the Mini-Mental State Examination. Yet, these impairments are not severe enough to warrant the diagnosis of mild cognitive impairment. Current subjective cognitive decline criteria could be expanded in order to increase the diagnostic precision of subjective cognitive decline.