Irritability is a common neuropsychiatric feature of Huntington’s disease (HD), with prevalences varying from 38% to 73%. Similar prevalences of irritability are reported in other neurodegenerative disorders and traumatic brain injury, especially when the frontal lobe is involved. Before therapeutic interventions are initiated, the clinician should analyze the severity and frequency of the irritable behavior. By examining irritability in a broader spectrum, a tailor-made treatment can be provided.
In general, I recommend as a first step a selective serotonin reuptake inhibitor (SSRI), such as sertraline, or the mood stabilizer valproate; they both have a mild side effect profile. Next, if the result is insufficient, I advise a switch between these two medications. As an alternative, I recommend a switch to a low dose of an atypical antipsychotic, preferably twice daily. Buspirone may be another alternative. Both antipsychotics and buspirone are also used as an add-on. Other mood stabilizers and beta-adrenergic receptor antagonists should only be used when earlier treatments are ineffective. The use of acetylcholinesterase inhibitors for the treatment of irritability is discouraged, as results are unclear. Synthetic cannabinoids are an interesting new therapeutic option, though their “illicit” compound and side effect profile make them not a first-line option.
It is important to identify possible comorbid psychiatric disorders, because irritability may be secondary to a psychiatric condition, and the choice of medication partly depends on the co-occurrence of a specific psychiatric disorder. For example, antipsychotic medication would be the treatment of choice in delusional HD patients with excessive irritability, instead of an SSRI or valproate.
Besides psychiatric comorbidity, the choice of medication also depends on the general medical condition, the side effect profile, and drug-drug interactions with other medications in concomitant use. Patients with advanced disease are particularly likely to be using various other types of medications.
In addition to pharmacotherapy, behavioral therapy or other psychotherapeutic interventions may be helpful to reduce levels of stress and should be considered.