Cognitive performance in REM sleep behaviour disorder: a possible early marker of neurodegenerative disease?
BACKGROUND
Rapid eye movement [REM] sleep behaviour disorder (RBD) may herald neurodegenerative diseases. Neurobiological deficits similar to those identified in neurodegenerative diseases have been reported in idiopathic RBD. Researchers are looking for early markers supporting a possible role of RBD as a harbinger of impending neurodegenerative disease.


OBJECTIVE
To examine the neuropsychological functions in idiopathic RBD subjects. Should they be found to present a neuropsychological dysfunction that overlaps that reported in neurodegenerative diseases, it would be possible to consider cognitive deficits as possible early markers of an underlying degenerative process.


METHODS
Twenty-three subjects with idiopathic RBD (21 males, mean age 67.0+/-7.0 years) and a group of healthy controls matched for sex, age and education underwent a neuropsychological battery evaluating different cognitive domains.


RESULTS
Considering mean values, poorer performances were observed in the Word Span (p<.001), Rey-Osterrieth's complex figure recall (p=.003), Digit Span (p=.003) and Logic Memory (p=.003) tests. On the basis of equivalent scores, the RBD subjects performed significantly more poorly on tests of visuo-constructional learning abilities (p<.001).


CONCLUSIONS
Our data show the possible presence of cognitive deficits in RBD defined as idiopathic, sharing common features in particular with Lewy body disease. Neuropsychological evaluation in RBD could lead to presymptomatic identification of neurodegenerative disease, but until more prolonged long-term follow-up data are available, the true neurobiological significance of cognitive deficits in RBD will remain unknown.
Terzaghi
Michele
M
Sleep Medicine Unit, IRCCS C Mondino Institute of Neurology Foundation, Via Mondino, Pavia, Italy. michele.terzaghi@mondino.it
Sinforiani
Elena
E
Zucchella
Chiara
C
Zambrelli
Elena
E
Pasotti
Chiara
C
Rustioni
Valter
V
Manni
Raffaele
R
D000368:Aged; D003072:Cognition Disorders / Q000175:diagnosis* / Q000523:psychology; D003704:Dementia / Q000175:diagnosis* / Q000523:psychology; D042241:Early Diagnosis; D005260:Female; D006801:Humans; D020961:Lewy Body Disease / Q000175:diagnosis / Q000523:psychology; D008297:Male; D011939:Mental Recall; D008875:Middle Aged; D019636:Neurodegenerative Diseases / Q000175:diagnosis* / Q000523:psychology; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D020734:Parkinsonian Disorders / Q000175:diagnosis / Q000523:psychology; D017286:Polysomnography; D011594:Psychometrics; D011597:Psychomotor Performance; D020187:REM Sleep Behavior Disorder / Q000175:diagnosis* / Q000523:psychology; D012016:Reference Values; D012153:Retention, Psychology; D014706:Verbal Learning