Heart Rate Variability in Huntington Disease: A Long-Term Longitudinal Study

The aim of the study was to follow tonic and phasic autonomic nervous activity in Huntington disease (HD) mutation carriers and patients.

Evaluation of motor functions and total functional capacity was performed in 30 HD mutation carriers or patients at the beginning and in 22 subjects after 8-10 years. Continuous arterial blood pressure, heart rate (HR), and ECG at rest were measured, and HR variability analysis was performed in four different ways. A group of matched controls was also evaluated.

Eighteen subjects were assorted in 3 groups: 6 HD mutation carriers without motor symptoms (PHD) who remained so (PHD-PHD); 6 early symptomatic patients (EHD) who remained so (EHD-EHD); and 6 early symptomatic patients who deteriorated to a late symptomatic (LHD) (EHD-LHD). At the beginning, sympathetic tonic activity in PHD was elevated, according to mean arterial pressure (99 ± 10.6 mm Hg) higher than in controls (85 ± 8.7 mm Hg) and EHD (82 ± 9.9 mm Hg) (Dunnett's test, p < 0.05) and higher HR (78 ± 16 beats/min) than after 8-10 years (64 ± 11.3 beats/min) (paired t test, p < 0.05). There was also a decreased phasic sympathetic activity in EHD patients compared controls at the beginning (219 ± 106 vs. 664 ± 466 s2/Hz) and after 8-10 years (182 ± 136 vs. 1,012 ± 1,369 s2/Hz) (Dunnett's test, p < 0.05). In patients who deteriorated from EHD to LHD, there was a drop in phasic parasympathetic activity from 887 ± 433 to 230 ± 235 s2/Hz (paired t test, p < 0.05).

Our long-term observational study provides important information on the timeline of ANS activity in HD progress. There was a temporary increase in cardiac and vascular sympathetic activity in PHD subjects. The normalization of HR in PHD subjects might indicate the approach of an outbreak of clinical disease phase.