Neurobehavioral Impairments in the Amyotrophic Lateral Sclerosis Continuum: A Systematic Review of Prevalence and Profile Features

Some patients with amyotrophic lateral sclerosis (ALS) exhibit neurobehavioral impairments, which can manifest as apathy, reduced empathy, poor self-regulation, or other dysexecutive problems. Neurobehavioral impairments in ALS are operationalized as multi-domain extra-motor changes in everyday functioning (i.e., behavior reports, subjective cognitive abilities, and emotional status) reflecting an underlying neurodegenerative process and not better explained by emotional adjustment to receiving a terminal diagnosis. Severity varies among patients, with some patients exhibiting coexisting behavioral variant frontotemporal dementia (ALS-bvFTD). This systematic review provides cumulative neurobehavioral impairment prevalence estimates among patients on the ALS continuum (i.e., total ALS patient population, including ALS-bvFTD) using data from standardized measures. Forty-one studies of patients with ALS were reviewed; neurobehavioral impairments were generally reported in three ways: 1) total neurobehavioral impairment (i.e., number of patients outside the cut score on individual measures); 2) neurobehavioral diagnostic classifications (i.e., ALS-bvFTD, ALS-behavioral impairment; ALSbi); and 3) specific neurobehavioral features. The cumulative prevalence estimate for total neurobehavioral impairment was 41% (k = 15; n = 1,276). For diagnostic group prevalence, total ALSbi: 19% (k = 4; n = 177), isolated ALSbi (i.e., without coexisting ALS-cognitive impairment): 13% (k = 4; n = 317), and ALS-bvFTD: 7% (k = 19; n = 1,065). Early ALS-bvFTD prevalence (within 12 months of ALS diagnosis) was higher: 13% (k = 3; n = 419). Impairments varied by measure and geographic region. Emotional features such as apathy, irritability, and poor emotion control were prominent. Additional research is needed to reduce bias and improve comprehensive assessment.