There appears to be a strong link between older veterans who suffered post-traumatic stress disorder and the later development of dementia though researchers are still searching for why that should be.
A press release from the Alzheimer's Association 2009 International Conference on Alzheimer's Disease in Vienna, Austria, reports the following:
The researchers found that veterans with PTSD in the study developed new cases of dementia at a rate of 10.6% over the seven years of follow-up; those without PTSD had a rate of 6.6%... Even after adjusting for demographics, and medical and psychiatric co-morbidities, PTSD patients in this study were still nearly twice as likely to develop incident dementia compared to veterans without PTSD... Results were similar when they excluded those with a history of traumatic brain injury, substance abuse or depression.
Here are some details of the study:
They studied 181,093 veterans aged 55 years and older without dementia (53,155 veterans diagnosed with PTSD and 127,938 veterans without PTSD) using data from the Department of Veterans Affairs National Patient Care Database. Mean baseline age of the veterans was 68.8 years and 97% were male. They followed the veterans from 2001 through 2007, including tracking whether they were diagnosed with Alzheimer's/dementia.
The Alheimer's Association provides the abstracts, the summaries of the research, as well.
A Reuters report had these reactions from experts:
"The million-dollar question is why," Dr. Ronald Petersen of the Alzheimer's Association and an Alzheimer's researcher at the Mayo Clinic in Rochester, Minnesota, said in a telephone interview...
"Further research is needed to fully understand what links these two important disorders," Yaffe said in a statement.
"With that knowledge we may be able to find ways to reduce the increased risk of dementia associated with PTSD," she said.
The same Reuters report has this passage about earlier research findings:
Some studies have found PTSD was linked with diminished brain volume in the hippocampus, a part of the brain involved in memory and stress response.
Another interesting research finding reported at the conference: moderate alcohol consumption appeared to lower the risk of dementia by nearly 40 percent.
Another excerpt from the press release:
After adjustment for demographics, smoking, co-morbidities, depression, social activity, and baseline cognition, moderate alcohol intake (1-2 drinks per day) was associated with a 37% lower risk of dementia in participants with normal cognition at baseline, but not in those with (moderate cognitive impairment.)