Huntington’s disease can be a devastating illness for patients and their families. The disease is directly inherited — if you have a parent with Huntington’s disease, you have a 50% chance of inheriting the abnormal huntingtin gene yourself. Unfortunately, if you inherit the huntingtin gene, you will certainly develop the disease. While there is no cure for Huntington’s disease, researchers in both clinical and basic neuroscience fields are working to unlock the mysteries of this disease and to find a cure.

The most striking feature of the Huntington’s disease is the bizarre and uncontrollable movement of various muscle groups. In fact, until recently the disease was more commonly referred to as Huntington’s chorea, since the choreatic, dance-like movements are a hallmark of the disease. While chorea as it is used in the word choreaography is usually rhythmic and graceful, chorea as a symptom is quite random and irregular. It is this disorder of movement that researchers in both the laboratory and the clinic have focused much of their efforts.

While chorea should be controlled if at all possible, there are other features of the disease that must also be recognized. George Huntington’s first description of the disease in 1872 included a comment about psychiatric illness as a cardinal feature of the disease [1]. He writes that the disease is invariably recognized by,

1. Its hereditary nature,
2. A tendency to insanity and suicide,
3. Its manifesting itself as a grave disease only in adult life.

In modern medicine we have mostly done away with the term “insanity,” yet the presence of psychiatric illness and suicide still exists in patients of Huntington’s disease today. Patients with Huntington’s disease suffer from psychological issues such as anxiety disorders, memory disturbances and depression. Estimates of the prevalence of neuropsychiatric symptoms in Huntington’s disease are between 33 to 76 percent of patients [2] although the true incidence and prevalence may be much higher. While we do not understand the precise neurobiological cause, it is clear that psychiatric symptoms occur much more frequently in patients of Huntington’s disease than in the general population. Further, neuropsychiatric symptoms are often the most distressing aspect of the disease for patients and their families and many times they necessitate hospitalization [3]. The most frequent psychiatric symptoms that occur with Huntington’s are depression, anxiety, irritability, obsession and compulsions and psychosis. Also, patients may have difficulty forming new memories and performing complex tasks.

Despite the fact that psychiatric illness was described in the earliest report on the disease, research as to how best to treat these conditions has been lacking. More than 218 papers have been published on the pharmacological treatment of Huntington’s disease and every one of them used chorea as the endpoint [4]. When it comes to treating psychiatric illness in Huntington’s disease, physicians do not have any clear guidelines or protocol. While limited anecdotal evidence exists for certain atypical antipsychotics and newer antidepressants, nothing even resembling a consensus exists for pharmacological treatment of these comorbid conditions.

Until there is a cure for Huntington’s disease, managing symptoms remains the primary focus of care. Psychiatric illnesses occur quite often in the disease — they should not go undiagnosed or untreated. While likely to contain few participants, properly controlled and blinded trials should be conducted that focus on psychiatric endpoints in Huntington’s disease such as anxiety, psychosis and depression. We have a growing armamentarium of treatments for psychiatric illness — exceedingly larger than what was known in George Huntington’s time. Physicians need to know which medicines are safe and which are most effective in patients that are already enduring so much. That knowledge will only come through the careful study of psychiatric illness as it occurs in Huntington’s disease.

References

1. Huntington G: On chorea. Med Surg Rep 1872; 26:317–32.

2. E. van Duijn, E.M. Kingma, R.C. van der Mast (2007). Psychopathology in Verified Huntington’s Disease Gene Carriers Journal of Neuropsychiatry, 19 (4), 441-448 DOI: 10.1176/appi.neuropsych.19.4.441

3. J M Hamilton (2003). Behavioural abnormalities contribute to functional decline in Huntington’s disease Journal of Neurology, Neurosurgery & Psychiatry, 74 (1), 120-122 DOI: 10.1136/jnnp.74.1.120

4. Raphael M. Bonelli, Gregor K. Wenning (2006). Pharmacological Management of Huntington’s Disease: An Evidence- Based Review Current Pharmaceutical Design, 12 (21), 2701-2720 DOI: 10.2174/138161206777698693