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Pathological laughter and crying (PLAC) is a common and distressing constellation of symptoms in many neurodegenerative conditions, differentiated from primary mood and anxiety disorders due to the presence of episodes of emotion inconsistent with or disproportionate to mood and not dependent on or excessive relative to a stimulus.1 Although laughter and crying are most commonly highlighted, other emotions can be exaggerated, including anger and irritability. PLAC remains underdiagnosed, with a focus on physical symptoms. It negatively impacts the psychological well-being of affected individuals and their carers.
The pathophysiology of PLAC remains poorly understood, making research challenging. In the UK, antidepressants remain the mainstay of treatment, with selective serotonin reuptake inhibitors and tricyclic antidepressants shown to reduce the frequency of PLAC episodes, but there are no established response rates and intolerable side-effects can limit use.2 In our clinical practice, symptoms often persisted despite antidepressants and remained impactful for patients and carers.
Nuedexta© is a formulation of dextromethorphan and quinidine (DM/Q), licenced in America for the treatment of PLAC in motor neuron disease (MND) and multiple sclerosis (MS). There is also emerging evidence for its potential to maintain or improve bulbar function in MND. Marketing approval was issued by the European Medicines Agency for Nuedexta©, but for commercial reasons, the company rescinded this. Dextromethorphan is available in over-the-counter dry cough mixtures and quinidine can be prescribed as an unlicensed suspension. A small case series suggested the tolerability of these two compound preparations and improvements …
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Contributors EH completed the review and wrote the manuscript.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Provenance and peer review Not commissioned; internally peer reviewed.
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