Background <p>The cognitive and behavioural changes that occur in around 50% of people with amyotrophic lateral sclerosis (ALS) may significantly affect people around them, contributing to heightened burden, anxiety, and depression. Despite existing evidence linking behavioural impairment to caregiver distress, the role of cognitive impairment remains less clear, with mixed findings on its impact.</p> Methods <p>This study assessed the influence of cognitive and behavioural impairments in people with ALS on the distress of their nominated informants. The data were collected face-to-face and remotely due to the COVID-19 pandemic. The cognitive and behavioural impairments were measured using established screening tools. Informants’ distress was evaluated through composite measures of burden, anxiety, and depression. Regression analyses were employed to determine the predictive value of cognitive and behavioural impairment on informant distress.</p> Results <p>A total of 98 ALS patients and 84 informants participated. Behavioural impairment predicted informant distress across various tools. In contrast, cognitive impairment was a less consistent predictor of informant distress across screening measures and did not significantly interact with behavioural impairment in predicting distress. Administration mode did not affect predictive relationships.</p> Conclusions <p>Behavioural impairment in ALS significantly predicts informant distress, with varying predictive power across different screening tools. Cognitive impairment also affects informant distress, but its impact is less substantial compared to behavioural factors. The interaction between cognitive and behavioural impairments did not significantly predict informant distress.</p>