Assessment of cognitive profile as a prodromal marker of the evolution of rapid eye movement sleep behavior disorder

Abstract

Study Objectives To search for a specific neuropsychological profile in idiopathic REM sleep behavior disorder (iRBD), able to predict the onset of neurodegenerative disorders. Methods In a longitudinal follow-up study of 63 consecutive iRBD patients (follow-up duration 6.7 ± 3.8 years), the baseline cognitive profile of converters to neurodegenerative disease was compared with that of the nonconverters. Five cognitive domains were assessed: memory, attention-working memory, executive functions, visuospatial abilities, language. Mild cognitive impairment (MCI) was diagnosed according to the Movement Disorder Society’s diagnostic criteria for Parkinson’s disease. Results 30 subjects (47.6%) developed a neurodegenerative disease (latency to conversion 60.33 ± 44.81 months). MCI was found in 50% of the converters and 12% of the nonconverters (p = .001), and its presence conferred a neurodegenerative disease risk of 10% at 3 years, 36% at 5 years, and 73% at 10 years (p = .002). Pathological equivalent scores on at least one neuropsychological test were detected in 46.7% of the converters versus 21.2% of the nonconverters in the memory domain (p = .032), in 40.0% versus 6.1% in that of executive functions (p = .002), and in 20.0% versus 3% in the visuospatial abilities domain (p = .047). On multivariate analysis, impaired executive functions significantly correlated with phenoconversion (p = .018). Lower Mini Mental State Examination (MMSE) scores (p = .004) and memory deficits (p = .031) were found in patients who developed dementia first. Conclusions Cognitive profile is useful for stratifying risk of phenoconversion in patients with iRBD. The presence of MCI and impaired executive functions, memory, and visuospatial abilities discriminated the converters. Lower MMSE scores and memory deficits may characterize those subjects who first develop dementia.

Possible predictors of phenoconversion in isolated REM sleep behaviour disorder: a systematic review and meta-analysis

“…The presence of MCI was evaluated according to the PD-MCI criteria 18. Longitudinal studies of consecutive patients with iRBD showed MCI in 50% of the converters, conferring a more severe neuroimaging and neurophysiological phenotype 19. Our finding agreed with preliminary studies that the presence of MCI might be a determinant suggestive of imminent phenoconversion.…”

Neuropsychiatric, neuropsychological, and neuroimaging features in isolated REM sleep behavior disorder: The importance of MCI

“…Considering the neuroimaging results, iRBD-MCI patients showed decreased striatal dopaminergic innervation in the right caudate and, to a lesser extent, in the remaining areas of both striata. This finding highlights the importance of diagnosing MCI in iRBD patients, as it is indicative of an increased presynaptic dopaminergic deficit, thus substantiating clinical data showing a higher risk of early conversion to alphasynucleinopathies in iRBD patients co-affected by MCI [42]. Moreover, the lateralized difference in SPECT data may reflect the previously documented higher presynaptic dopaminergic damage in the right caudate of PD patients with MCI than in those with NC [43].…”

Biomarkers of conversion to α-synucleinopathy in isolated rapid-eye-movement sleep behaviour disorder

“…1,21 Indeed, both amnestic and non-amnestic mild cognitive impairment subtypes in patients with isolated RBD are predictive of the development of dementia with Lewy bodies or parkinsonism with cognitive impairment. 1,[22][23][24] Deficits in cognitive performance also affect patients with isolated RBD who do not fulfill criteria for mild cognitive impairment. 21 Cross-sectional studies have reported deficits in attention, executive function, memory, and visuospatial function in this population, 21 and pareidolias (the tendency to perceive a meaningful image in an ambiguous visual pattern) and deficits in prospective memory have also been identified.…”