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Is there an association between neurological disorders and a higher risk of death by suicide?
In this retrospective cohort study that included 7 300 395 persons in Denmark from 1980 through 2016, there was a significantly higher rate of suicide among those with a diagnosed neurological disorder than all other persons (44.0 per 100 000 person-years vs 20.1 per 100 000 person-years, adjusted incidence rate ratio, 1.8).
In Denmark, having a diagnosis of a neurological disorder was associated with a small but statistically significant increased risk of death by suicide.
Neurological disorders have been linked to suicide, but the risk across a broad spectrum of neurological disorders remains to be assessed.
To examine whether people with neurological disorders die by suicide more often than other people and to assess for temporal associations.
Design, Setting, and Participants
Nationwide, retrospective cohort study on all persons 15 years or older living in Denmark, from 1980 through 2016 (N = 7 300 395).
Medical contact for head injury, stroke, epilepsy, polyneuropathy, diseases of myoneural junction, Parkinson disease, multiple sclerosis, central nervous system infections, meningitis, encephalitis, amyotrophic lateral sclerosis, Huntington disease, dementia, intellectual disability, and other brain diseases from 1977 through 2016 (n = 1 248 252).
Main Outcomes and Measures
Death by suicide during 1980-2016. Adjusted incidence rate ratio (IRRs) were estimated using Poisson regressions, adjusted for sociodemographics, comorbidity, psychiatric diagnoses, and self-harm.
Of the more than 7.3 million individuals observed over 161 935 233 person-years (49.1% males), 35 483 died by suicide (median duration of follow-up, 23.6 years; interquartile range, 10.0-37.0 years; mean age, 51.9 years; SD, 17.9 years). Of those, 77.4% were males, and 14.7% (n = 5141) were diagnosed with a neurological disorder, equivalent to a suicide rate of 44.0 per 100 000 person-years compared with 20.1 per 100 000 person-years among individuals not diagnosed with a neurological disorder. People diagnosed with a neurological disorder had an adjusted IRR of 1.8 (95% CI, 1.7-1.8) compared with those not diagnosed. The excess adjusted IRRs were 4.9 (95% CI, 3.5-6.9) for amyotrophic lateral sclerosis, 4.9 (95% CI, 3.1-7.7) for Huntington disease, 2.2 (95% CI, 1.9-2.6) for multiple sclerosis, 1.7 (95% CI, 1.6-1.7) for head injury, 1.3 (95% CI, 1.2-1.3) for stroke, and 1.7 (95% CI, 1.6-1.8) for epilepsy. The association varied according to time since diagnosis with an adjusted IRR for 1 to 3 months of 3.1 (95% CI, 2.7-3.6) and for 10 or more years, 1.5 (95% CI, 1.4 to 1.6, P < .001). Compared with those who were not diagnosed with a neurological disorder, those with dementia had a lower overall adjusted IRR of 0.8 (95% CI, 0.7-0.9), which was elevated during the first month after diagnosis to 3.0 (95% CI, 1.9-4.6; P < .001). The absolute risk of suicide for people with Huntington disease was 1.6% (95% CI, 1.0%-2.5%).
Conclusions and Relevance
In Denmark from 1980 through 2016, there was a significantly higher rate of suicide among those with a diagnosed neurological disorder than persons not diagnosed with a neurological disorder. However, the absolute risk difference was small.
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Corresponding Author: Annette Erlangsen, PhD, Danish Research Institute for Suicide Prevention, Mental Health Centre Copenhagen, Gentofte Hospitalsvej 15, 4, DK-2900 Hellerup, Denmark (firstname.lastname@example.org).
Accepted for Publication: December 14, 2019.
Author Contributions: Dr Erlangsen had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Concept and design: Erlangsen, Egon Stenager, Conwell, Hawton, Benros, Nordentoft, Elsebeth Stenager.
Acquisition, analysis, or interpretation of data: Erlangsen, Egon Stenager, Conwell, Andersen, Hawton, Benros, Elsebeth Stenager.
Drafting of the manuscript: Erlangsen, Hawton.
Critical revision of the manuscript for important intellectual content: Egon Stenager, Conwell, Andersen, Hawton, Benros, Nordentoft, Elsebeth Stenager.
Statistical analysis: Erlangsen, Andersen, Nordentoft.
Obtained funding: Elsebeth Stenager.
Administrative, technical, or material support: Elsebeth Stenager.
Supervision: Benros, Nordentoft, Elsebeth Stenager.
Conflict of Interest Disclosures: None reported.
Funding/Support: Supported by a grant from the Psychiatric Research Foundation, Region of Southern Denmark, Denmark.
Role of the Funder/Sponsor: The funder had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.
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