Sustaining a head injury of any type was associated with an increased risk for future suicide attempts.

In a large cohort study that included more than 1.8 million adults, those with head injuries were 21% more likely to attempt suicide within a mean of 5 years compared to those without head injuries.

All subgroups with head injuries also had a significantly increased risk, including those with no history of mental health conditions.

“Our findings show that the impact of head injuries is not limited to just physical symptoms or repercussions. They can have profound psychological consequences,” study author Nicola Adderley, PhD, professor of epidemiology and real-world experience at the University of Birmingham in Birmingham, England, said in a release.

“Suicide risk assessments should be considered for anyone with a recent head injury…to improve and safeguard patient outcomes,” Adderley added. 

The findings were published online on December 22 in Neurology.

First Study of Its Kind

Previous studies have shown a significant association between traumatic brain injury (TBI) and risk for future suicide attempts. However, only 20% of head injuries are deemed to be TBIs, the investigators noted.

They wanted to examine the risk for suicide attempts in all types of head injury — making it the first study of its kind to assess this issue in a general population, they noted.

The 20-year population-based matched cohort study used health records for more than 1.8 million adults (mean age, 52 years; 51% women) linked to hospital and national statistics data. Those with a head injury (mean follow-up, 5.5 years) were matched 1:4 with participants without this type of injury (mean follow-up, 4 years).

“Head injury is defined as any injury to the head other than superficial injuries to the face and is responsible for 1.4 million people attending the emergency department each year in the United Kingdom,” the researchers reported.

The primary outcome was the risk for suicide attempts. Other outcomes included the risk for death by suicide and suicide attempt risk factors.

Among the head injury group, there were 5107 suicide attempts (1.3%) during follow-up. Incidence rates for the attempts were 2.4 vs 1.6 per 1000 person-years for the head-injury and noninjury groups, respectively (adjusted hazard ratio [HR], 1.21).

While the adjusted HR for death by suicide was 0.74, it was no longer significant after controlling for the risk for death by other causes (sub-HR, 0.91).

Twelve months or more after head injury was associated with a significantly lower risk for suicide attempt compared to within the first 5 months after injury (P < .001); White individuals had a significantly lower risk than Black or Asian (P < .001) or mixed ethnic individuals (P = .004); and those with depression, schizophrenia, bipolar disorder, or substance use disorder at baseline had a higher risk than those without mental health conditions (all, P < .001).

However, the risk for attempts was high in all of the head injury subgroups assessed, including those without a history of mental health conditions.

“These findings have implications for both clinical practice and health policy, highlighting the urgent need for targeted mental health and wellbeing support,” study author G. Neil Thomas, PhD, University of Birmingham, said in the release.

‘Minor’ Blow, Major Implications

In an accompanying editorial, Erin D. Bigler, PhD, Department of Psychology and Neuroscience Center at Brigham Young University in Provo, Utah, and Steven Allder, DM, consultant neurologist and clinical director at Re:Cognition Health, London, England, noted the findings show that suicide risk isn’t limited to patients with “radiographically-proven” brain injury.

“Many ‘minor’ head traumas documented in primary care — often dismissed as inconsequential — may nonetheless perturb neural circuits that regulate mood, impulse control, and decision-making,” Bigler and Allder wrote.

“The study’s magnitude and methodologic rigor render its conclusions difficult to ignore. Head injury in any form should trigger heightened clinical vigilance,” they added.

The editorialists noted that future research is needed to identify patients at the greatest risk for posttraumatic suicidality, especially studies that combine neuroimaging, digital behavioral monitoring, and serum biomarkers of neural injury. 

Until then, the current study provides “compelling evidence that even a ‘minor’ blow to the head warrants major attention to mental health,” they concluded.

The investigators reported no relevant financial relationships. Disclosures for the editorialists are fully listed in the original article.