Attenuated error-related potentials in amyotrophic lateral sclerosis with executive dysfunctions.

OBJECTIVE: Executive dysfunctions affect up to 50% of the patients with amyotrophic lateral sclerosis (ALS). Executive dysfunctions have been identified as negative prognostic factor and can affect quality of life in patients and their caregivers. Assessment of executive dysfunction may be impeded by the patients' motor impairments. Event-related potentials (ERP) have been proposed as a tool to overcome these assessment difficulties. The error(-related) negativity (Ne/ERN) is an ERP which can be recorded with minimal motor requirements for the patient. METHODS: We compared response-synchronized ERP amplitudes of 18 ALS patients and 19 healthy controls (HC) obtained on error trials on a flanker task. We also evaluated the relation between Ne/ERN amplitudes and executive functions as assessed by standardized neuropsychological measures. RESULTS: While response-synchronized ERP amplitudes were generally unaffected by ALS, we found an ALS-associated relation between Ne/ERN amplitudes and executive functions. ALS patients with poorer executive functioning showed attenuated Ne/ERN amplitudes. CONCLUSIONS: Our data suggest that Ne/ERN amplitudes reflect ALS-associated impairment of executive functions, potentially due to disturbances in neural networks that involve the anterior cingulate cortex. SIGNIFICANCE: Assessment of Ne/ERN amplitudes might provide a cost-efficient and non-invasive marker for executive dysfunction in ALS.