The objective of the study was to investigate whether cognitive and behavioural impairment in Amyotrophic Lateral Sclerosis (ALS) contributes to caregiver burden, and whether carer burden affects patient outcome. Thirty-three dyads of incident patients with ALS and their primary caregivers (n = 33) completed a series of measures to determine cognitive and behavioural profiles, (patients) and carer burden (carers) to investigate the psychological impact of ALS, and the impact of behavioural change since the onset of ALS. Caregivers were divided into high- and low-burden groups using previously established norms. High burden in carers was associated with significantly higher apathy (p = 0.009), disinhibition (p = 0.005), and executive dysfunction (p = 0.015) in patients. Regression analyses for burden confirmed significant predictors such as change in apathy (r = 0.390, F = 5.19, p = 0.03), disinhibition (r = 0.530, F = 11.32, p = 0.002), and executive dysfunction (r = 0.372, F = 4.66, p = 0.039), with total behaviour change contributing to 31 % of caregiver burden (r = 0.563, F = 4.17, p = 0.015). Total distress as measured by the Hospital Anxiety and Depression Scale was also a significant predictor of caregiver burden, contributing to 38.5 % of variance (r = 0.621, F = 18.79, p < 0.000). Caregiver burden did not affect survival (p = 0.496). Caregiver burden in ALS is modulated by patient's cognitive and behavioural status, but does not significantly impact patient survival.