Cognitive Reserve in Isolated Rapid Eye-Movement Sleep Behavior Disorder

Abstract

Isolated rapid-eye-movement sleep behaviour disorder (RBD) is considered the prodromal stage of α-synucleinopathies (e.g., Parkinson’s disease and dementia with Lewy bodies); however, iRBD patients show a wide variety in the progression timing (5–15 years). The model of cognitive reserve (CR) might contribute to explaining this phenomenon. Our exploratory study aimed to evaluate, for the first time, the impact of CR level on cognitive performance in polysomnography-confirmed iRBD patients. Fifty-five iRBD patients (mean age ± SD: 66.38 ± 7.51; M/F 44/11) underwent clinical and neuropsychological evaluations at the time of diagnosis. The CR Index questionnaire was part of the clinical assessment. We found that iRBD patients with high levels of CR showed: (i) the lowest percentage of mild cognitive impairment (10%), and (ii) the best performance in visuo-constructive and verbal memory functions (i.e., the recall of the Rey–Osterrieth complex figure test). Our results suggest that CR might help iRBD patients better cope with the cognitive decline related to the neurodegenerative process, providing the first preliminary findings supporting CR as a possible protective factor in this condition. This might pave the way for future longitudinal studies to evaluate the role of CR as a modulating factor in the timing of iRBD conversion and cognitive deterioration development.

The Mechanisms of Sleep Function and Regulation for Health and Cognitive Performance

“…The results showed not only the involvement of different brain regions in the cognitive performance but also the importance of a balance between physical activities and sleep for cognitive functioning in short-sleep population. Notably, D'Este et al [5] evaluated the influence of cognitive reserve on cognitive performance in isolated rapid-eye-movement sleep behavior disorder (iRBD) patients. The results showed that, in this specific sleep disorder group, patients with high levels of cognitive reserve achieved the best performance in visuo-constructive and verbal memory functions and reported a lower percentage of mild cognitive impairment.…”