Diminished event-related cortical arousals and altered heart rate response in Parkinson's disease

In Parkinson's disease (PD), partial neuronal loss occurs in several arousal-promoting structures, but the effects on arousability have not yet been studied.

Polysomnographic analysis of 70 PD patients and 70 control subjects matched for age, sex, body mass index, apnea-hypopnea index (AHI), and periodic limb movements in sleep index (PLMSI).

In PD patients, arousal frequency was diminished by 50% compared with controls (9.1 ± 7.6 vs. 18.6 ± 22.9/h; P < 0.001), and the correlations with AHI (rho = 0.266 vs. 0.503, P = 0.004) and PLMSI (rho = 0.082 vs. 0.354, P = 0.006) were weaker. Hoehn & Yahr stage was an independent negative predictor of arousal index (β = -0.297, P = 0.015). Normalization of heart rate increase after cortical arousals was prolonged in PD patients compared with controls (P = 0.003).

Our findings indicate that the neurodegenerative process in PD is associated with an attenuated arousability to respiratory and motor events, and with an alteration of the heart rate pattern accompanying arousals.