Huntington's Disease: Premotor Phase

Abstract

Huntington's disease (HD) is an incurable, neurodegenerative disease, which manifests via a triad of progressive symptoms: motor impairment, psychiatric disorders, and cognitive decline. Conventionally, the HD diagnosis is based on the presence of involuntary choreiform movements and a positive genetic test for the CAG-expanded allele gene. Although the diagnosis focuses on the motor part of the triad, there is increasing evidence that both cognitive and neuropsychiatric symptoms can, and often do, present decades before the onset of motor symptoms. In this paper, we review the evidence regarding the symptoms in the HD premotor phase and summarize the most relevant and robust studies in the last few years. Regarding neuropsychiatric symptoms, higher levels of depression, anxiety, apathy, irritability, psychosis, disinhibition, hostility, and sleeping problems were found. In terms of cognition, there was impairment in attention, working memory, episodic memory, language, recognition of facial emotions, empathy, and theory of mind. These early symptoms of HD can be very debilitating and are often disregarded by doctors. It is necessary to acknowledge them so that they can be treated or alleviated. Moreover, an earlier diagnosis can lead to the implementation of neurodegenerative prevention therapies, which may slow the progression of the disease and prolong overall functioning. This will improve the patient's independence and their quality of life.

Keywords: Diagnosis; Huntington’s disease; Premotor phase.