Sleep and Huntington Disease: Polysomnographic Findings and Clinical Correlates

Huntington’s disease (HD) is a progressive, fatal, neurodegenerative disorder caused by an abnormal expansion of a CAG repeat sequence in the gene encoding the protein huntingtin (HTT) on chromosome 4. Clinical features of HD include progressive motor dysfunction, cognitive decline, and psychiatric disturbance. Sleep disturbances are frequent in HD patients. However, sleep alterations as well as their association with other symptoms and signs of the disease have not been systematically studied in large groups of HD patients.The aim of the study was to objectively evaluate sleep features in a large, single-center, population of HD patients by means of nocturnal, laboratory based video-polysomnography (V-PSG), and to correlate PSG findings with clinical parameters;evaluate subjective sleep-related symptoms by subjective sleep evaluation and compare the results with those obtained with the gold standard diagnostic tool, namely V-PSG;finally, evaluate the EEG modifications in HD patients during the sleep-wake cycle, by means of the exact LOw REsolution Tomography (eLORETA) software.The results suggest that sleep is severely disrupted in HD patients.Taken together,our data may suggest that the caudate degenerative process observed in HD account for the increased arousability, increased motor activity during wake and sleep (originating periodic limb movements), reduction of REM sleep and, overall, a general sleep disruption.As concerns the subjective sleep evaluation, our data suggest, overall, that the subjective evaluation of sleep in HD patients shows a poor correlation with PSG results. Our EEG data suggest a defined pattern of motor cortex dysfunction during wake and sleep, which correlates with the clinical and polysomnographic evidence of increased motor activity during wake and NREM, and nearly absent motor abnormalities in REM. It could be hypothesized that EEG modifications reflect motor cortex impairment or, conversely, an effort to counterbalance abnormal motor output.