Longitudinal predictors of caregiver burden in amyotrophic lateral sclerosis: a population-based cohort of patient-caregiver dyads

Caregiver burden is a recognised consequence of caring for a patient with neurodegeneration. Amyotrophic lateral sclerosis (ALS) differs from other neurodegenerations by its rapid progression and impairment of motor, cognitive, and behavioural function, which contribute to caregiver burden. However, longitudinal factors that determine the extent of caregiver burden, and in particular the impact of psychological distress among caregivers, have not been fully established. Patients with ALS (n = 85) and their primary caregivers (n = 85) completed three serial evaluations. Caregiver burden was measured using the Zarit Burden Interview (ZBI). Anxiety and depression were evaluated using the Hospital Anxiety and Depression Scale (HADS). The Edinburgh Cognitive-Behavioural ALS Screen (ECAS) was used to determine cognitive function in patients. The ALS Functional Rating Scale (ALSFRS-R) measured disease progression. Using the ZBI, caregivers were categorised as high or low burden. In the low burden group, anxiety scores from the HADS predicted caregiver burden (r = 0.410, F = 3.73, p = 0.033), whereas the depression sub-score from the HADS was predictive of caregiver burden in the high burden group (r = 0.501, F = 5.87, p = 0.006) for cross-sectional analyses. Longitudinally, an elevated score on the HADS at Time 1 was the largest predictor of caregiver burden across serial assessments. In a patient cohort with relatively preserved cognitive function (65%), anxiety and depression at Time 1, as measured by the HADS, were the best predictors of caregiver burden at Time 3. This observation provides a mechanism by which caregiver burden can be identified by health-care professionals and a stepped care programme of intervention initiated.