Obsessive and/or compulsive symptoms occur frequently in Huntington's and often worsen as the disease progresses [Beglinger 2007]. Obsessions are persistent and unwelcome thoughts which are often accompanied by compulsions which are the behaviors associated with obsessive thoughts. As an example, the thought of absolute need for cleanliness can be followed by the behavior of obsessive hand washing. Obsessive and compulsive symptoms are very distressing, and they are often impossible for the person to control. These symptoms always cause high levels of anxiety.

Treatments for Obsessive Compulsive Behavior: There is no single drug that is used for obsessive and compulsive symptoms in Huntington's or any other disease. First line treatments are SSRI antidepressant drugs, several of which have been FDA approved for obsessive compulsive symptoms. These include fluoxetine (Prozac®), paroxetine (Paxil®), sertaline (Zoloft®), and fluvoxamine (Luvox®). The NSRI antidepressant drug venlafaxine (Effexor®) has been approved for severe anxiety and is also used for obsessive compulsive symptoms. Often higher doses of these drugs are needed than those used for depression. Mirtazepine (Remeron®) is an atypical antidepressant that is FDA approved for and increasingly used for obsessive compulsive disorders. Clomipramine (Anafranil®) is a tricyclic antidepressant that is no longer considered a first line drug, but is sometime used as an "add-on" if other drugs have not controlled symptoms.

Antipsychotic drugs are used for this condition only when other drugs are not successful, often as an "add on. There is a single case report of successful use of the antipsychotic drug olanzapine (Zyprexa®) for this symptom in Huntington's [Paleacu 2002]. Risperidone (Risperdal®) or quetiapine (Seroquel®) are other drugs from this class that can be added if other medications fail.  Mood stabilizers are only rarely used if all other drugs fail.  

References

Beglinger LJ, Langbehn DR, Duff K, Stierman L, Black DW, Nehl C, Anderson K, Penziner E, Paulsen JS, Huntington Study Group Investigators. Probability of obsessive and compulsive symptoms in Huntington's disease. Biol Psychiatry 2007 Feb 1;61(3):415-8. PubMed abstract

Paleacu D, Anca M, Giladi N. Olanzapine in Huntington's disease. Acta Neurol Scand 2002 Jun;105(6):441-4. PubMed abstract