Pathological laughter or crying (shortened to PLC) refers to laughter or crying that is deemed socially inappropriate for the situation. Often the individual will laugh or cry spontaneously for no apparent reason. The abnormal behavior is one of impaired emotional expression. Can this be a symptom of Huntington's disease; and if so how can it be treated?
PLC is a symptom that has been reported in several neurologic disorders including traumatic brain injury, multiple sclerosis, Parkinson's disease, stroke and most frequently in amyotrophic lateral sclerosis (ALS) [Parvizi J 2006]. It has also been described in dementia associated with Alzheimer's disease [Starkstein SE 1995]. Though not reported (to my knowledge) in Huntington's disease (HD) it almost certainly does occur.
The reasons why this symptom occurs in several neurologic diseases is not known, but certainly involves disordered network connections between the cortex, or surface of the brain and deeper brain structures in the brainstem. The diversity of disease states in which PLC occurs suggests many different pathways can be involved.
PLC is Emotional Dysregulation: Impairment in recognizing emotion in others by their facial expression is common and occurs early in HD. Pathological laughing and crying is at the opposite end of the spectrum and is thought to be one of the types of impairment in regulation of expressing emotion.
PLC responds to Treatment: The good news is that this symptom often responds to both selective serotonin uptake inhibitor (SSRI) and tricyclic antidepressant drugs [Parvizi J 2006]. The SSRI group of medications that include sertraline, citalopram, etc., is the safer of these two alternatives for HD. Dose ranges cited include both low and high. I'd recommend starting low and increasing as needed with the goal being decreasing the level of severity, not trying to eradicate.
Parvizi J, Arciniegas DB, Bernardini GL, Hoffmann MW, Mohr JP, Rapoport MJ, Schmahmann JD, Silver JM, Tuhrim S. Diagnosis and management of pathological laughter and crying. Mayo Clin Proc. 2006 Nov;81(11):1482-6. PubMed abstract
Starkstein SE, Migliorelli R, Tesón A, Petracca G, Chemerinsky E, Manes F, Leiguarda R. Prevalence and clinical correlates of pathological affective display in Alzheimer's disease. J Neurol Neurosurg Psychiatry. 1995 Jul;59(1):55-60. PubMed abstract