Cognitive deficits associated with restless legs syndrome (RLS)

BACKGROUND AND PURPOSE: Restless legs syndrome produces significant chronic sleep loss, which despite not causing expected profound sleepiness, might nonetheless produce cognitive deficits similar to those seen with acute sleep deprivation, i.e. involving mostly pre-frontal cortical (PFC) functioning. PATIENTS AND METHODS: Sixteen patients off RLS treatment for at least 2 weeks and 15 age- and gender-matched control subjects had polysomnograms (PSGs) on two consecutive nights. Cognitive tests were given in the morning after the second night. Six cognitive tests were used: two Verbal Fluency tests and the Trail Making tests were selected to be particularly sensitive to PFC function and sleep loss. Porteus Mazes and the Stroop Test were selected to reflect more general frontal and executive function. The Colored Progressive Matrices were used to assess general cognitive skills. RESULTS: RLS patients compared to controls showed significant (P<0.05) and sizeable (20-40%) deficits on two of the three PFC tests and marginally non-significant deficit (P<0.1) on the third. The other three tests showed no significant differences. CONCLUSIONS: The results indicate that RLS patients show cognitive deficits similar to that reported for one night of sleep loss.