Suicide was more common among people with a diagnosed neurologic disorder, a nationwide retrospective analysis in Denmark showed.

Over a 37-year period, the suicide rate for people with a neurologic disorder was 44.0 per 100,000 person-years, compared with 20.1 per 100,000 person years for all other people, reported Annette Erlangsen, PhD, of the Danish Research Institute for Suicide Prevention/Mental Health Centre Copenhagen, and colleagues in JAMA.

Head injury accounted for 4.5% of all suicides, stroke accounted for 3.5%, and epilepsy accounted for 3.0%. In total, one out of 150 people with a neurologic disorder died from suicide, Erlangsen said; for severe conditions like Huntington's disease, that number rose to one in 61.

"For some neurological disorders, we found a four to fives times higher suicide rate when compared with the general population," she told MedPage Today. "Still, it is important to emphasize that suicide deaths are rare events."

The findings demonstrate it is "crucial to increase screening for suicide in people with neurological disorders so they can be referred for psychiatric services on time," noted Tatiana Falcone, MD, a psychiatrist with the Cleveland Clinic Epilepsy Center, who wasn't involved in the study.

The study shows an increased association between the number of hospital contacts and suicide "which makes a great case for screening patients in different settings such as the emergency department," Falcone told MedPage Today. "Patients might consult with a different complaint but might have suicidal thoughts and could receive the help they need immediately."

This analysis is the most comprehensive look at neurologic disorders and suicide to date, Erlangsen said. Studies of less prevalent disorders like Huntington's disease and amyotrophic lateral sclerosis (ALS) have been inconclusive, she noted, although population-based studies have linked head injury, stroke, epilepsy, and multiple sclerosis (MS) with suicide.

"Individuals with multiple sclerosis have repeatedly been shown to be at higher risk for death from suicide than the rest of the population," pointed out Philip Brenner, MD, PhD, of the Karolinska Institute in Stockholm, who wasn't part of the study.

"Apart from the immense tragedy that these deaths entail -- many of which should be preventable -- one should also keep in mind that this is likely to reflect the high rates of mental distress, including depression, among individuals with MS," he told MedPage Today. "Whether this is due to the disability MS may confer, the neuroinflammatory impact on the brain inherent to the disease, or both is unknown."

In their study, Erlangsen and colleagues looked at all people age 15 or older living in Denmark from 1980 through 2016 (7,300,395 people over 161,935,233 person-years; 49.9% were males) and identified 1,248,252 people who had medical contact for head injury, stroke, epilepsy, polyneuropathy, diseases of myoneural junction, Parkinson's, MS, central nervous system infections, meningitis, encephalitis, ALS, Huntington's, dementia, intellectual disability, and other brain disorders.

In total, 35,483 people died from suicide over a median follow-up of 23.6 years. Of those, 77.4% were males and 5,141 people (14.7%) were diagnosed with a neurologic disorder.

In models adjusted for demographics, physical comorbidity, and pre-existing psychiatric diagnoses, people with a neurologic disorder had a suicide incidence rate ratio of 1.8 (95% CI 1.7-1.8) compared with all others. The highest suicide rate occurred between the first and third months after being diagnosed (3.1, 95% CI 2.7-3.6).

Rates were highest for people diagnosed with ALS (4.9) and Huntington's disease (4.9). People with multiple sclerosis (2.2), head injury (1.7), epilepsy (1.7), and stroke (1.3) also had higher suicide rates than people without neurologic disorders.

Compared with people who not did have a neurologic diagnosis, people with dementia had a lower suicide rate (0.8), as did people with Alzheimer's disease (0.2). In the first month after diagnosis, however, the suicide rate ratio among dementia patients was 3.0.

Suicide rate increased with the cumulative number of hospital contacts for neurologic conditions: it was 1.7 for one admission; 1.8 for two to three admissions, and 2.1 for more than four admissions. MS patients who had four or more hospital contacts had a suicide rate twice as high as those with only one contact.

"This study presents a comprehensive overview which will enable the field of suicide prevention to evaluate whether there are specific neurological disorders one should be more attentive towards and specific periods," Erlangsen said.

"For healthcare providers, it might be useful to be aware of depressive symptoms among patients with neurological disorders," she added. "We found that the time of diagnosis was associated with an elevated risk. Being diagnosed with a severe chronic disorder might be a quite distressing experience and perhaps more support is needed during this period."

The study has several limitations, the researchers noted. People who were diagnosed before 1977 were not included if no further hospital contact took place. Diagnoses given in primary care were not included, and suicides may have been under-reported. Fully adjusted models accounted for pre-existing mental disorders, which may be considered over-adjustment, they added.