Unawareness of motor phenoconversion in Huntington disease

Abstract

Objective: To determine whether Huntington disease (HD) mutation carriers have motor symptoms (complaints) when definite motor onset (motor phenoconversion) is diagnosed and document differences between the groups with and without unawareness of motor signs.

Methods: We analyzed data from 550 HD mutation carriers participating in the multicenter PREDICT-HD Study followed through the HD prodrome. Data analysis included demographics, the Unified Huntington's Disease Rating Scale (UHDRS) and the Participant HD History of symptoms, self-report of progression, and cognitive, behavioral, and imaging measures. Unawareness was identified when no motor symptoms were self-reported but when definite motor HD was diagnosed.

Results: Of 38 (6.91%) with onset of motor HD, almost half (18/38 = 47.36%) had no motor symptoms despite signs of disease on the UHDRS motor rating and consistent with unawareness. A group with motor symptoms and signs was similar on a range of measures to the unaware group. Those with unawareness of HD signs reported less depression. Patients with symptoms had more striatal atrophy on imaging measures.

Conclusions: Only half of the patients with newly diagnosed motor HD had motor symptoms. Unaware patients were less likely to be depressed. Self-report of symptoms may be inaccurate in HD at the earliest stage.