Brain scans of 10 persons with Down syndrome but no dementia, 10 persons with Down syndrome and dementia, and 10 healthy controls, have revealed a linear correlation between cognitive ability and compromised white matter connections in the frontal lobes among those with Down syndrome. Those with higher cognitive ability and motor skill coordination had healthier white matter integrity, and those with additional dementia showed the most deterioration.
Adults with Down Syndrome are known to be at high risk of developing Alzheimer’s after age 40.
(2014). Frontal white matter integrity in adults with Down syndrome with and without dementia.
Neurobiology of Aging. 35(7), 1562 - 1569.