Emotionalism, Emotional Lability
Emotionalism or emotional lability, or emotional incontinence, implies both frequent and unpredictable changes in emotional expression, for example tearfulness followed shortly by elation, and an inappropriate expression of emotion, for example uncontrollable ("uninhibited" or disinhibited) laughter or crying.
A distinction may be drawn between the occurrence of these phenomena spontaneously or without motivation, or in situations which although funny or sad are not particularly so. Also, a distinction may be made between such phenomena when there is congruence of mood and affect, sometimes labeled with terms, such as moria or witzelsucht(e.g., laughing when feeling happy or elated), and when there is no such congruence (e.g., laughing when not feeling happy or elated), sometimes labeled as pathological, forced, or inappropriate laughter and crying (q.v.).
The neurobehavioral state of emotional lability reflects frontal lobe (especially orbitofrontal) lesions, often vascular in origin, and may coexist with disinhibited behavior. It is commoner in vascular dementia than Alzheimer’s disease. It may also be seen in delirium and in psychiatric disorders (mania). Pathological laughter and crying may occur as one component of pseudobulbar palsy ("pseudobulbar affect").
Heilman KM, Blonder LX, Bowers D, Valenstein E. Emotional disorders associated with neurological diseases. In: Heilman KM, Valenstein E (eds.). Clinical neuropsychology (4th edition). Oxford: OUP, 2003: 447-478