For the first time ever, doctors have documented a patient with HIV that has been diagnosed with Alzheimer's disease, which suggests that HIV survivors are beginning to live long enough to reach ages where they are at risk of the degenerative disease.
The case was discovered in a 71-year-old man through a medical scan that revealed the presence of amyloid protein clumps in his brain. Although scientists believed that HIV-related inflammation in the brain has the potential to prevent the formation of these clumps, the new case provides evidence that conflicts with this theory.
"This patient may be a sentinel case that disputes what we thought we knew about dementia in HIV-positive individuals," said Scott Turner, author of the study and a member of the Memory Disorders Program at Georgetown University Medical Center.
Furthermore, the case suggests that certain older people with both HIV and dementia might have been misdiagnosed with HIV-associated neurocognitive disorders (HAND) that actually stem from Alzheimer's disease. However, it is also possible that these older people also have disorders stemming from both HIV and Alzheimer's disease.
"Chronic HIV infection and amyloid deposition with aging may represent a 'double-hit' to the brain that results in progressive dementia," Turner said.
"While it may be challenging to diagnose the cause of dementia in an HIV-positive patient, the diagnosis matters because HAND and AD are treated differently," he added. "For Alzheimer's disease, we now have four FDA-approved drugs and more effective treatments are on the way. For HAND, we prescribe anti-retroviral drugs that have a better chance of penetrating the brain. So getting a correct diagnosis is important, and a critical first step in advancing the field."
Approximately 30 to 50 percent of individuals with long-term HIV infections develop HAND, but the difficulty lies in the fact that symptoms mirror those found in people with Alzheimer's disease.
"The medical community assumes that dementia with HIV is caused by HAND," Turner said. "Physicians haven't considered Alzheimer's, so it's possible that a number of older HIV-positive individuals may be misdiagnosed."
The new results will help scientists better diagnose dementia in HIV-infected individuals over the age of 55, the fastest growing age group in the HIV-positive population.
The findings were published online in the April 15 issue of the journal Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring.
