(Source: Journal of the American Medical Association, news release, Feb. 11, 2008)

People with a personal or family history of learning disabilities may be more at risk for a rare type of dementia that causes them to lose language abilities as they age, according to a new report.

The condition, known as primary progressive aphasia, causes language abilities to be slowly and progressively impaired, even though the person’s other brain functions appear unaffected for at least the first two years, according to background information for the article in the February issue of Archives of Neurology.

Although risk factors for Alzheimer’s disease have been well studied, much less is known about risk factors for primary progressive aphasia, the authors wrote.

Researchers, led by Emily Rogalski, then of Northwestern University and now of Rush University Medical Center in Chicago, studied 699 people — about half with no dementia and the other half with either primary progressive aphasia, Alzheimer’s disease or a related disorder known as frontotemporal dementia.

Patients with primary progressive aphasia were more likely to have had learning disabilities or a close family member with learning disabilities than were those with other forms of dementia or without dementia. The review of patients with both aphasia and learning disabilities showed families with unusually high rates of learning problems, especially dyslexia.

For example, in three cases, nine of the 10 children of the participants were reported to have had a history of specific learning disability in the area of language, the authors wrote.

“In our clinical practice, we encounter many patients with primary progressive aphasia who report that spelling was never their strong suit or that they could not learn new languages, but who would not have identified themselves as having a learning disability,” they continued.

The association suggests that some people or families may have an underlying susceptibility to difficulties with the language network.

“This relationship may exist in only a small subgroup of persons with dyslexia without necessarily implying that the entire population with dyslexia or their family members are at higher risk of primary progressive aphasia,” the authors concluded.