Amyotrophic lateral sclerosis type 8 is not a pure motor disease: evidence from a neuropsychological and behavioural...

Amyotrophic lateral sclerosis type 8 (ALS8) is a familial form of motor neuron disease, with predominance of lower motor neuron degeneration, and is caused by mutation of the vesicle-associated membrane protein-associated protein B (VAPB). We aimed to compare the cognitive profile of patients with ALS8 and healthy controls (HC), and to screen for behavioural features in ALS8 patients.

The sample was composed of ALS8 patients (n = 22; 14 men; median age 48 years old; median disease duration 6.5 years) and HC (n = 33; 19 men; median age 48 years old). Patients and HC were matched for sex, age and educational level. Participants underwent behavioural, psychiatric (Hospital Anxiety and Depression Scale and Cambridge Behavioural Inventory-Revised) and neuropsychological assessments, focused on executive functions, visual memory, and facial emotion recognition.

ALS8 patients exhibited subtle deficits in executive functions. Compared to controls, ALS8 patients were significantly impaired in measures of flexibility and inhibitory control. ALS8 patients and HC did not differ in scores of facial emotion recognition. There was clinically relevant anxiety and depression in 36% and 27% of ALS8 patients, respectively. Behavioural disorders such as stereotypic and motor behaviours were present in more than 30% of patients.

ALS8 patients present mild executive dysfunction and behavioural changes such as mood disorders, apathy and stereotypic behaviour. Our findings suggest that ALS8 is not a pure motor disorder and it is associated with subtle cognitive and behavioural impairments.