Suffering a major traumatic brain injury (TBI) increases the risk of new-onset dementia compared to persons who do not have a TBI, suggests a new study reported in the journal Neurology. Patients with minor head injury were not at risk of developing dementia.1

Data for the study was sourced from a Finnish national database updated every five years with information collected through surveys. Focusing on a 20-year period, from 1992–2012, they identified 31,909 people, aged 25–64 years, who completed one or more surveys, which included details on lifestyle factors such as physical activity, smoking and alcohol use. The objective of the study was to determine the association between TBI and risk of dementia.

Out of the total 31,909 study subjects, there were 288 hospitalizations due to a major TBI (defined as traumatic intracranial hemorrhage and hospitalization for ≥3 days), while 406 hospitalizations were due to a minor head injury (defined as concussion and hospitalization for ≤1 day).

Over the follow up period of nearly 16 years (median), new onset dementia was detected in 976 patients. Twenty-seven patients (9%) with major TBI and 9 patients (2%) with mild TBI developed dementia, whereas 940 individuals (3%) without any head injury developed dementia.

Risk of incident dementia was 1.5 times higher in those who were admitted to hospitals due to a major head injury compared to those who did not have a TBI. However, this association, note the authors, diminished in significance (HR 1.3) after adjusting for age, sex, physical activity, high BP and alcohol intake. The two factors strongly downplaying this association were physical activity and alcohol use.

Patients with minor head injury were not found to be at risk of dementia. Calling for further research, the authors say, “prevention of other dementia risk factors such as excess alcohol consumption and physical inactivity could possibly reduce the risk of dementia in people with major TBI”.

Reference

1. Rahul Raj, et al. Risk of dementia after hospitalization due to traumatic brain injury: a longitudinal, population-based study. Neurology. May 2022, 10.1212/WNL.0000000000200290; DOI: 10.1212/WNL.0000000000200290