There are many risks associated with serving in the military, but it may be that some risks continue long after this service has ended.
A recent study published in Neurology that examined a group of older veterans found there could be a link between traumatic brain injuries (TBI) and the development of dementia.
Dementia is defined by the National Institute of Neurological Disorders and Stroke as a collection of symptoms that are caused by a number of disorders that affect the brain. People with dementia have impaired intellectual and cognitive functioning, and also experience behavioral and personality changes.
Dementia is a major health care issue in the US. Alzheimer's disease, the most common form of dementia, currently affects 5.3 million Americans. It is the sixth leading cause of death in the country, and the fifth leading cause in people aged 65 and over.
The research in Neurology followed 188,784 veterans who had an average age of 68 when the study began. All participants were free of dementia and had had at least one visit to a Department of Veterans Affairs (VA) health care facility.
A 'frequent' occupational hazard
TBI can occur when the head is hit suddenly and violently, or when an object pierces the skull and penetrates the brain. They can cause a range of symptoms, from mild cases causing headaches and nausea to severe cases resulting in permanent brain damage and death.
Military personnel in active service regularly face the risk of traumatic brain injury.
The VA state that, at present, occurrences of TBI due to blast injury are frequent in military personnel engaged in active combat in Iraq and Afghanistan.
Of the 188,784 veterans studied, 1,229 had been diagnosed with a TBI. During the study's follow-up period, 16% of these veterans developed dementia. This figure was compared with the 18,225 without a TBI, of whom 10% developed dementia.
The researchers took into account other factors known to increase the risk of dementia, such as alcoholism, depression, diabetes and high blood pressure, and concluded that veterans diagnosed with a TBI were 60% more likely to develop dementia than veterans without a TBI.
They also found that veterans with a TBI developed dementia 2 years earlier than those without a TBI, at an average age of 78.5, compared with 80.7. In addition, those with TBI that did not develop dementia died 2.3 years earlier than the veterans without a TBI.
Veterans with a TBI who additionally had depression, post-traumatic stress disorder or cerebrovascular disease were found to have a higher risk of dementia than veterans who solely had those conditions or a TBI alone.
Increased risk for civilians?
Study author Deborah E. Barnes, Ph.D, MPH, of the University of California-San Francisco, the San Francisco VA Medical Center and a member of the American Academy of Neurology (AAN), drew the following conclusions from the study:
"These findings suggest that a history of TBI contributes risk for dementia in later life in veterans. If we assume that this relationship is causal, it seems likely that the same increased risk probably occurs with TBI in the civilian population as well."
An editorial is linked to the study in Neurology, and its author Dr. Rodolfo Savica, of the University of Utah School of Medicine in Salt Lake City, and a member of the AAN, urges caution:
"This study convincingly shows that mild trauma has a role in increasing the risk of dementia and sheds light on the more complex relationship between medical and psychiatric diseases with TBI in the development of the future risk of dementias. Neuroscientists must take a careful and comprehensive approach and avoid oversimplified claims of causality."
If further research finds that the relationship between a history of TBI and dementia is causal, then this will have implications for the public. Although military personnel are a high-risk group, half of TBIs occur as a result of motor vehicle accidents. TBIs can also be caused by accidents during sport and work.
Recently, Medical News Today reported on a study that suggested longer education was linked to better recovery from TBI.