A report that recently caught the attention of the American press was that Post Traumatic Stress Syndrome, or PTSD, in our soldiers returning from Iraq and Afghanistan may increase their risk of developing Alzheimer's dementia. Unfortunately, the situation is more alarming than this.
In some cases, the development of Alzheimer's dementia is determined by the presence of certain genes at birth. However, in the majority of cases, the development of Alzheimer's and other forms of dementia is the result of the acquisition of various risk factors throughout life. PTSD is only one of many such risk factors that are seen in increasingly large numbers among our veterans.
In Alzheimer's dementia, the brain becomes clogged with deposits of crystallized protein called amyloid and tangles of another abnormally processed protein called tau. Certain genes predispose individuals to the build up of these substances. However, medical conditions such as diabetes, heart disease, obesity, and sleep apnea substantially increase the likelihood of abnormal processing of these brain substances and the subsequent development of Alzheimer's dementia.
A condition known as Metabolic Syndrome is often the starting point for those conditions. Metabolic Syndrome presents as high blood pressure; high triglycerides; low levels of the good cholesterol, HDL; high fasting blood sugar levels; and pot-bellied, abdominal obesity. Metabolic Syndrome is currently being seen in about 25% of Americans, with substantially higher prevalence among veterans.
Psychiatric conditions, such as Major Depression, further increase the likelihood of Metabolic Syndrome. Major Depression also independently increases the risk of heart disease, diabetes, obesity, and, not surprisingly, Alzheimer's dementia. PTSD is a psychiatric condition that may arise under conditions of extreme stress and horror, such as may be experienced in combat. PTSD presents with constant wariness, anxiety, and inability to relax. There is withdrawal from people, irritability, flashbacks, and nightmares. Relationships fail, jobs are lost, and lives are devastated. Major Depression, substance abuse, and sleep disorders are common co-morbidities.
The relationship to PTSD or war weariness is unclear, but the incidences of Major Depression and substance abuse are increasing among veterans. The recently noted increase in the suicide rate among American soldiers gives grim testimony to this fact. Nearly 43% of veterans with PTSD are also found to develop metabolic syndrome, with the highest prevalence among those with the most severe symptoms of PTSD. It is not clear if PTSD itself increases the risk of dementia, or if the conditions that PTSD leads to are responsible for the increased risk. However, current evidence suggests that having PTSD increases the risk of Alzheimer's dementia by over 30%.
Head trauma, the signature injury of the Iraq and Afghanistan wars, makes its own contribution to dementia. One would expect Traumatic Brain Injury, or TBI, to cause changes in cognitive function. However, it is being found that aside from the immediate effects on brain structure and function, TBI can initiate amyloid deposition and neurofibrillary tangles that are the primary neurodegenerative processes of dementia. In some cases, the risk of Alzheimer's dementia may increase even in the absence of remarkable acute changes in cognition. Depending on the presence of certain genetic features, TBI may as much as double the risk of Alzheimer's dementia.
In view of the accelerating incidence of Metabolic Syndrome, heart disease, diabetes, Major Depression, substance abuse, PTSD, and TBI among our veterans, the VA and the veterans it serves may soon be facing a heart wrenching and extremely expensive epidemic of dementia.