Combat veterans may continue to feel the impact of their years of service, decades after returning home. Over the past few years, a connection between the physical and mental effects of war and dementia risk has been unearthed in a series of studies conducted by researchers from the University of California, San Francisco (UCSF).

The latest UCSF investigation, links prior traumatic brain injury (TBI) with a 60 percent increase in dementia among veterans in their mid-to-late 60s. A finding that study authors say "raises concern about the potential long-term consequences of TBI in younger veterans," especially those just returning from the wars in Iraq and Afghanistan.

Some of the veterans who didn't have a pre-existing TBI still ended up developing dementia, but the onset of their condition tended to occur two years later than those who'd sustained a significant head injury in the field.

Determining how head trauma accelerates the dementia process still remains an elusive goal for researchers. Some theorize that it contributes to the buildup of beta amyloid plaques, identified as an indicator of Alzheimer's disease, the most common form of dementia. Others believe that it's simply a matter having the added complication of TBI on top of other processes that contribute to dementia, such as genetics, heart disease and depression.

In a separate investigation, UCSF researchers also found that veterans who suffered from post-traumatic stress disorder (PTSD) were nearly twice as likely to grapple with dementia in their later years, compared to those who didn't have the psychological condition.

PTSD is a prevalent ailment among veterans of modern wars. Twelve percent of soldiers who served in World War II and the Korean War still struggle with PTSD. The condition also plagues as many as 30 percent of Vietnam veterans and 17 percent of those returning from the Afghanistan and Iraq wars.

Study authors believe that the connection between PTSD and dementia may arise from a few different factors:

PTSD itself has a negative impact on a person's overall mental functioning, reducing their cognitive reserve (the brain's natural defense against dementia) and contributing to the accelerated onset of dementia later in life.

PTSD creates feelings of chronic stress, which can harm the hippocampus, the part of the brain that is essential to learning and memory formation. Long-term stress can also cause damaging inflammation in the brain.

People with PTSD may be more often diagnosed with dementia because they are already being monitored by mental health practitioners who are actively keeping tabs on changes in their mental well-being.

A multitude of conditions—from diabetes to sleep apnea—have been identified as contributing to the development of cognitive difficulties among aging adults. The reality is that each factor is just one part of a complex disease process that has yet to be fully unraveled and understood by scientists.

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One thing is clear: the more of these conditions a person has, the greater the likelihood that they'll experience life-altering cognitive impairment as they age.

While some forms of dementia—Alzheimer's disease, Lewy Body dementia, vascular disease and Pick's disease—cannot be entirely prevented or cured, a person can minimize their overall chances of developing cognitive impairment and other signs of dementia by managing certain controllable risk factors.

A healthy diet, regular exercise regimen and seeking professional help when grappling with excessive stress and depression are simple ways to mitigate dementia risk. A recent idea that has given renewed hope to the medical community is the concept of "cognitive reserve"—the brain's ability to create new neural pathways to compensate for some of the physical damage done by certain forms of dementia.

Studies have shown that cognitive reserve can be built (regardless of a person's age) by engaging in stimulating mental activities. These activities go beyond doing a daily crossword of Sudoku puzzle, but are still simple enough to do during your daily life. For some examples of daily activities that can help generate this dementia buffer, see 8 Ways to Construct Cognitive Reserve.