Objective: To determine whether cognitive dysfunction and depression are more prevalent in RLS subjects compared to controls, and if RLS severity impacts these variables.

Background: RLS is a gradually progressive sensorimotor disorder with associated impairment of energy, sleep and performance. Prior studies have shown variability in results while assessing cognitive function and mood in those with RLS. Generalization of prior findings has been limited due to small sample sizes. Our study evaluated the impact of differing severity of RLS on cognitive functioning and depression using a larger sample size.

Method: A retrospective analysis was performed on 681 subjects (161 with RLS). All participants completed cognitive testing, movement exam, sleep and mood questionnaires. The RLS group was subdivided into three subgroups based on IRLSS score (Group 1: 0-6; Group 2: 7-13, Group 3: 14 and above). General linear regression adjusted for age, gender and education was performed to evaluate for association between controls, RLS subgroups and outcomes. A false discovery rate method was used to control for multiplicity, with a p-value less than or equal to 0.015 considered significant.

Results: Analysis of cognitive functioning demonstrated statistically significant difference between controls and the RLS groups for AVLT total learning (p=0.006), AVLT long term memory (p=0.003) and Stroop Word/Color (p=0.004). When these were adjusted for Epsworth Sleepiness Scale (ESS), there was no statistically significant difference noted: AVLT TL(p=0.018), AVLT LTM(p=0.015), Stroop Word/Color(p=0.208). ESS demonstrated mean score of 5.7 in controls, 7.2 in group 1, 7.5 in group 2 and 9.3 in group 3. Also noted was a statistically significant difference in depression as measured by HAM-D and the Geriatric Depression Scale(p <0.001 for both) between RLS and controls, with no noted difference between RLS subgroups.

Conclusion: The above data demonstrates reduced performance in attention and recall domains of cognitive testing in RLS subjects. However, this finding is negated when adjusted for sleep quality, with strong correlation noted between sleep quality and RLS severity. Our data also demonstrates increased prevalence of depression among those with RLS compared to controls. However, increased RLS severity did not increase severity of depression in our population.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/impact-of-restless-leg-syndrome-rls-severity-on-cognitive-function-and-depression/