Nonmotor symptoms may underlie Parkinson’s sleep complaints

By Joanna Lyford, Senior medwireNews Reporter

In people with Parkinson’s disease (PD), symptoms and comorbidities associated with insomnia differ from those associated with daytime sleepiness, US researchers report.

The team found that nonmotor features such as depression and autonomic symptoms were associated with subjective reports of insomnia, whereas fatigue and dopaminergic medication were associated with sleepiness.

“Our results suggest that clinicians should pay particular attention to uncontrolled non-motor features as potential causes or results of insomnia or daytime sleepiness,” write Seockhoon Chung (University of Michigan, Ann Arbor) and colleagues in the Journal of Clinical Sleep Medicine.

The team assessed 128 PD patients for insomnia, sleepiness, fatigue, disease severity, depression, and autonomic symptoms; 38 of the participants also underwent nocturnal polysomnography and sleep latency testing.

The mean age of participants was 65.7 years, 75% were men, and the mean duration of PD was 5.9 years.

Multivariate logistic regression analysis showed that the severity of nonmotor symptoms, rather than motor symptoms, was primarily associated with subjective insomnia at an odds ratio (OR) of 2.58 per standard deviation increase on the Unified Parkinson Disease Rating Scale part I. Increasing severity of depressive symptoms (OR=1.79) autonomic symptoms (OR=1.77), and fatigue (OR=1.19) all independently predicted insomnia severity, as did younger age (OR=0.61).

Meanwhile, two factors predicted the severity of sleepiness: levodopa-equivalent medication dosage (OR=1.74) and fatigue severity (OR=1.14).

Among the subset of people who underwent polysomnography, both sleep latency and sleep efficiency correlated with autonomic symptoms. Also, 74% of patients had obstructive sleep apnea, and scores on the apnea-hypopnea index correlated with daytime sleepiness.

Chung and co-authors conclude that clinicians should routinely assess PD patients for sleepiness and fatigue using subjective rating scales. Laboratory-based sleep studies may also be informative if obstructive sleep apnea is suspected, they add.

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