Individuals diagnosed with a neurological disorder have a significantly higher rate of suicide compared with those without this diagnosis, according to results of a nationwide, retrospective cohort study conducted in Denmark and published in JAMA.
“Population-based studies have associated head injury, stroke, epilepsy and multiple sclerosis with suicide,” Annette Erlangsen, PhD, of the Danish Research Institute for Suicide Prevention, and colleagues wrote. “Findings related to less prevalent neurological disorders, such as amyotrophic lateral sclerosis, Huntington disease and Parkinson disease, were inconclusive due to small sample sizes, selection bias and suboptimal comparison groups while not being adjusted for relevant confounders, such as physical and mental comorbidity.”
To examine whether individuals with neurological disorders have a higher likelihood of death by suicide than those without these disorders, the researchers collected data from three Danish databases, as well as from labor market registers, on 7,300,395 people aged 15 years or older living in Denmark from 1980 through 2016. They used death by suicide during this period as the main outcome and estimated adjusted incidence rate ratios (IRRs) using Poisson regressions, adjusted for self-harm, intellectual disability, psychiatric diagnoses and sociodemographics.
Erlangsen and colleagues found that among all individuals observed over 161,935,233 person-years, 35,483 died by suicide. Of these, 77.4% were men and 14.7% (n = 5,141) had been diagnosed with a neurological disorder. The suicide rate for those with a neurological disorder was 44 per 100,000 person-years (adjusted IRR = 1.8; 95% CI, 1.7-1.8) compared with 20.1 per 100,000 person-years for those without one. The excess adjusted IRRs by neurological disease were as follows:
- Amyotrophic lateral sclerosis = 4.9 (95% CI, 3.5-6.9);
- Huntington disease = 4.9 (95% CI, 3.1-7.7);
- multiple sclerosis = 2.2 (95% CI, 1.9-2.6);
- stroke = 1.3 (95% CI, 1.2-1.3); and
- epilepsy = 1.7 (95% CI, 1.6-1.8).
At 1 to 3 months, the adjusted IRR was 3.1 (95% CI, 2.7-3.6) and at 10 or more years, it was 1.5 (95% CI, 1.4-1.6). Those with dementia had a lower overall adjusted IRR of 0.8 (95% CI, 0.7-0.9) compared with those who were not diagnosed with a neurological disorder. Those with dementia experienced an elevated adjusted IRR of 3 (95% CI, 1.9-4.6) in the first month after diagnosis. Those with Huntington disease had an absolute risk for suicide of 1.6% (95% CI, 1-2.5).
“This study design cannot establish causality,” the researchers wrote. “However, there are plausible mechanisms that could link the examined disorders to suicide.”
These potential mechanisms included diagnosis constituting a distressing life event, disease-related psychological consequences and reduced financial security. – by Joe Gramigna
Disclosures: The authors report no relevant financial disclosures.