IEED is also commonly known as pseudobulbar affect, emotional lability, pathological laughing and crying, and emotional incontinence.

Involuntary emotional expression disorder (IEED) is associated with neurologic diseases such as MS, ALS, Parkinson’s disease, dementias including Alzheimer’s disease, and neurologic injuries such as stroke and traumatic brain injury.^{Arciniegas DB, Topkoff J; Kaschka WP, Meyers A, Schier KR, et al} 

Prevalence estimates place the number of people with IEED around 1.5 million in the United States alone.^{Arciniegas DB, Lauterbach EC, Anderson KE, et al}  However, given the fact that IEED is a relatively common disorder among patients with various neurologic conditions, its actual prevalence may be higher.^{Arciniegas DB, Lauterbach EC, Anderson KE, et al} 

Estimated Ranges of IEED Prevalence in Published Literature

 

Underlying Neurological Condition	Patients with IEED (%)
Amyotrophic lateral sclerosis (ALS)Schiffer R, Pope LE	49%
Alzheimer’s diseaseStarkstein SE, Migliorelli R, Teson A, et al	39%
StrokeKim JS, Choi-Kwon S	34%
Multiple sclerosis (MS)Schiffer R, Pope LE	11%
Traumatic brain injury (TBI)Tateno A, Jorge RE, Robinson RG	10%
Parkinson's disease (PD)	Observed