Cognitive Impairment and Dementia (Mild or Major Neurocognitive Disorder) in Huntington’s Disease

Abstract

The original descriptions of Huntington’s disease focused so predominantly on the involuntary choreatic movements that the disease was known as Huntington’s chorea. As an understanding evolved that this inherited disorder was characterized as much by cognitive and mood disturbances as it was by motor impairment, the term chorea, derived from the Greek word for dance, was dropped from the name in the 1980s. While less prevalent and less well studied than other neurodegenerative diseases, the ability to identify people with the genetic mutation who will ultimately, and with certainty, develop Huntington’s disease allows for investigation of the lifelong course of this disease well beyond what can be done for other major neurodegenerative diseases. As such, the cognitive deficits that appear along the continuum of the progression of Huntington’s disease have been well characterized. It is now known that cognitive impairments are detectable as long as 15 years before the clinical diagnosis of HD. In this chapter, we describe the phenomenology of the cognitive decline that occurs over the course of the disease and how the profile is unique from other diseases. We present both the domains of cognition most impacted in the disease as well as the specific cognitive tests that are the most sensitive in this population. Lastly, we highlight some of the upcoming clinical trials that will include cognition as an endpoint for this devastating disease.