A severe head injury, especially during middle age, could dramatically increase the risk for developing dementia later in life, according to research published in PLOS Medicine. The study included 40,639 Finnish adults between 18 and 65 who had been hospitalized with mild, moderate, or severe traumatic brain injuries (TBIs). The injuries occurred between 1987 and 2014. The researchers followed the study participants for about 11 years. The 20,703 mild TBI patients were hospitalized for less than a day. The 19,936 moderate-to-severe traumatic brain injury patients had been hospitalized for a minimum of 3 days.
The largest increase in risk was seen among those who had a TBI between ages 41 and 50. Their odds of dementia were nearly triple those of someone with a mild injury. For those who had a TBI between ages 51 and 60, the odds of dementia were doubled, the researchers found. More people in the moderate-to-severe group also developed dementia before the age of 65, compared to those in the mild group (40 vs 26%).