Dementia due to Huntington’s Disease

Clinical Features

Dementia Opens in new window is also a characteristic of Huntington’s disease, an autosomal dominant inheritable condition localized to chromosome 4. Unfortunately, this condition does not become apparent until age 35 to 45 years, usually after childbearing has occurred. Fifty percent of offspring are affected. There is also a juvenile form of the disease. Huntington’s disease affects about 4 in 100 000 people, making it a significant cause of dementia in middle-aged adults.

The most noticeable clinical feature of Huntington’s disease is the movement disorder, which involves both choreiform movements (frequent movements that cause a jerking motion of the body) and athetosis (slow writhing movements).

In the juvenile form of Huntington’s disease, which represents about 3% of all cases, the chorea is replaced by dystonia, akinesia, and rigidity, and the course of the disease is more rapid than in the adult form. In the early stages of the disease, the chorea is not as noticeable and may be disguised by the patient by making the movements seem purposeful.

The dementia typically begins between one year before and one year after the chorea and, unlike patients with other dementias, patients with Huntington’s disease are often well aware of their deteriorating mentation. This may be a factor in the high rates of suicide and alcoholism associated with this condition.

Although attempts have been made to increase ACh and GABA concentrations in these patients, such pharmacological interventions have been unsuccessful, and the dementia is untreatable. Genetic counseling is indicated.