Mortality among family members of patients with amyotrophic lateral sclerosis - a Swedish register-based study

Objective: To test two hypotheses: (1) partners of ALS patients have higher mortality due to outcomes related to psychological distress, and (2) parents and siblings of ALS patients have higher mortality due to diseases that co-occur with ALS.Methods: We performed a nationwide, register-based cohort study in Sweden. We included ALS-free partners, biological parents and full siblings (N = 11,704) of ALS patients, as well as ALS-free partners, biological parents and full siblings (N = 14,460,150) of ALS-free individuals, and followed them during 1961-2013. Hazard ratios (HRs) and 95% confidence intervals (CIs) of overall and cause-specific mortality were derived from Cox regression.Results: Partners of ALS patients, compared to partners of ALS-free individuals, displayed higher mortality due to external causes (HR 2.14; 95% CI 1.35-3.41), including suicide (HR 2.44; 95% CI 1.09-5.44) and accidents (HR 2.09; 95% CI 1.12-3.90), after diagnosis of the ALS patients. Parents of ALS patients had a slightly higher overall mortality (HR 1.03; 95% CI 1.00-1.07), compared with parents of ALS-free individuals. This was driven by mortality due to dementias and cardiovascular, respiratory, and skin diseases. Parents of ALS patients had, however, lower mortality than parents of ALS-free individuals due to neoplasms. Siblings of ALS patients had higher mortality due to dementias, and digestive and skin diseases.Conclusions: Increased mortality due to suicide and accidents among partners of ALS patients is likely attributable to severe psychological distress following the ALS diagnosis. Increased mortality due to dementias among parents and full siblings of ALS patients suggests shared mechanisms between neurodegenerative diseases.