Cognitive impairment in motor neuron disease with bulbar onset

METHODS: Twenty-three patients with bulbar onset motor neuron disease/amyot rophic lateral sclerosis (MND/ALS) were clinically assessed. They subsequen tly underwent serial neuropsychological testing, event-related potentials ( ERP) and SPECT studies. Cognitive impairment was defined by clinical eviden ce of dementia (DSM-IV and frontal evaluation) or by significant alteration indicated by neuropsychological testing (excluding patients with depressio n and major anxiety), or both. RESULTS: Eleven patients (48%) were found to be cognitively impaired. Abnor malities indicated fronto-temporal involvement, with memory impairment, alt eration of judgement and reasoning, reduced speech, behavioural dyscontrol and alteration of daily living activities. This impairment correlated well with event-related potentials and SPECT studies. Event-related potentials w ere the most sensitive test as 100% of the impaired patients had abnormal E RP (p = 0.04). The cognitively impaired group differed from the other group mainly by gender ratio (male/female) with an important male predominance: 1,75 vs. 0.33. MND/ALS was also more severe when decline was present. CONCLUSION: This study adds further arguments for a cognitive impairment in MND/ALS, This also reinforces the hypothesis that there is continuum betwe en MND/ALS and fronto-temporal lobe dementia.