Restless Legs Syndrome and Cognitive Function: A Population-based Cross-sectional Study.
BACKGROUND
Restless legs syndrome has been speculated to be linked to cognitive impairment through vascular risk factors or through its effect on sleep deprivation. Previous studies on the association between restless legs syndrome and cognitive function have been inconclusive. We performed a cross-sectional analysis of the association between restless legs syndrome and cognitive function using data from a large population-based study of elderly individuals residing in France.


METHODS
We used information from 2070 individuals from the Dijon, France center of the Three-City study who had available information on restless legs syndrome and cognitive functioning measures. Restless legs syndrome was assessed using the 4 minimal diagnostic criteria of the International Restless Legs Study Group. During the same wave in which restless legs syndrome status was assessed, cognitive functions also were assessed using 4 tests: Isaacs' test of verbal/category fluency, the Benton Visual Retention Test, the Trail Making Test B, and the Mini-Mental State Examination. We created a summary global cognitive score by summing the z scores for the 4 tests and used analysis of covariance to explore the association between restless legs syndrome and cognitive function.


RESULTS
We did not observe any statistically significant differences in any cognitive z-score between those with restless legs syndrome and those without restless legs syndrome. The mean global z-score after multivariate adjustment was -0.003 (SE 0.173) for those with restless legs syndrome and -0.007 (SE 0.129) for those without restless legs syndrome (P-value = .98).


CONCLUSIONS
Data from this large, population-based study do not suggest that restless legs syndrome is associated with prevalent cognitive deficits in elderly individuals.
Division of Preventive Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Mass; Department of Epidemiology, Harvard TH Chan School of Public Health, Boston, Mass.
Pamela M
PM
Rist
Social and Occupational Determinants of Health, INSERM Centre for Research in Epidemiology and Population Health, Villejuif, France; Université de Versailles St-Quentin, UMRS 1018, Versailles, France.
Alexis
A
Elbaz
Team Neuroepidemiology, INSERM Research Center for Epidemiology and Biostatistics, Bordeaux, France; College of Health Sciences, University of Bordeaux, Bordeaux, France.
Carole
C
Dufouil
Team Neuroepidemiology, INSERM Research Center for Epidemiology and Biostatistics, Bordeaux, France; College of Health Sciences, University of Bordeaux, Bordeaux, France.
Christophe
C
Tzourio
Division of Preventive Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Mass; Department of Epidemiology, Harvard TH Chan School of Public Health, Boston, Mass; Team Neuroepidemiology, INSERM Research Center for Epidemiology and Biostatistics, Bordeaux, France; College of Health Sciences, University of Bordeaux, Bordeaux, France. Electronic address: tobias.kurth@u-bordeaux.fr.
Tobias
T
Kurth
D000369:Aged, 80 and over; D003071:Cognition; D003072:Cognition Disorders / Q000209:etiology; D003430:Cross-Sectional Studies; D005260:Female; D005602:France; D006801:Humans; D008297:Male; D012148:Restless Legs Syndrome / Q000523:psychology*; D012307:Risk Factors
Cognitive function; Epidemiology; Restless legs syndrome