Repeat brain injuries linked to higher mental health risks – study

Young adults with previous brain injuries had higher odds of a new mental health diagnosis within a year of mild traumatic brain injury, a study found.

Those with two or more previous injuries had more than six times the odds of a new diagnosis compared with patients without a history of traumatic brain injury (TBI).

Hospital admission and pre-existing psychiatric conditions were also associated with increased odds, although previous TBI was the strongest predictor.

The study analysed electronic health records covering 9,835 mild TBI events among 8,985 adults aged 18 to 45 between 2000 and 2020.

Mild TBI was defined using a Glasgow Coma Scale score of 14 or 15, a clinical measure of consciousness following brain injury.

Patients admitted to intensive care or without continuous follow-up records were excluded.

Within 12 months of injury, 538 events, or 5.5 per cent, were followed by a new mental health diagnosis.

Those who received a diagnosis were generally older and more likely to have experienced previous brain injuries.

Among patients with a new diagnosis, 56 per cent had a history of TBI, compared with 19 per cent of those without a new mental health diagnosis.

Hospital admission following the injury was also more common, at 22 per cent compared with 9.9 per cent.

After adjusting for other measured characteristics, researchers found that one previous TBI was associated with 3.90 times the odds of a new mental health diagnosis.

For patients with two or more previous injuries, the adjusted odds were 6.37 times those of people without a history of TBI.

Hospitalisation following the current injury was associated with 1.79 times the odds of a new diagnosis, while a pre-existing psychiatric history was associated with 1.84 times the odds.

The association with previous brain injuries remained after accounting for psychiatric history and hospitalisation.

However, the findings do not establish that repeated injuries directly cause subsequent mental health conditions.

The researchers also examined healthcare use during the year after injury, including emergency department visits, hospital admissions and days spent in hospital.

Records came from a tertiary district referral hospital and an integrated healthcare organisation, allowing patients to be tracked across hospital and community settings.

The authors suggested that identifying patients with previous brain injuries, psychiatric conditions or a need for hospital admission could help clinicians determine who might benefit from closer monitoring.

Structured follow-up and preventive mental health interventions could help address the longer-term psychological and social effects of mild TBI.

The findings may be particularly relevant to emergency departments and outpatient services, where clinicians could use patients’ medical histories to identify those needing additional support.

Study limitations

The study relied on diagnoses recorded in electronic health records using ICD-9 diagnostic codes.

Mental health problems that were not identified or documented by healthcare professionals would therefore not have been captured.

Excluding patients without continuous follow-up records and those admitted to intensive care also limits how widely the findings can be applied.

As a retrospective observational study, the research identifies associations rather than proving that previous injuries caused subsequent mental health disorders.

The researchers concluded that assessing previous head injuries, psychiatric history and hospitalisation status could help identify young adults who may need structured mental health follow-up during the first year after mild TBI.