COLUMBUS, Ohio - People whose diagnosis of AIDS was based on specific illnesses are at greater risk of developing memory problems than are people whose diagnosis grew from low immune-cell counts, new research shows.
The study found that AIDS patients who were diagnosed because of so-called AIDS-defining illnesses, such as Kaposi's sarcoma, are most at risk for memory loss and other cognitive problems, including dementia.
The findings are important because the life-preserving treatment regimens taken by people with AIDS are very complex, and a person with memory or cognitive problems may not be able to follow those regimens.
"It is important to identify those who are at risk for dementia and to help them to the extent that we can," said Robert Bornstein, professor and chair of psychiatry at Ohio State University and co-author of the study.
"Not following a treatment regimen can allow medication-resistant strains of the virus to evolve in that person because of the way the virus interacts with these drugs."
Furthermore, he said, "the same cognitive difficulties that influence a person's ability to follow their medication regimen can contribute to increased risky behavior, and an increased risk of HIV transmission. Then you end up with a person who is transmitting a drug-resistant strain of the virus, which raises a broader public health concern."
Doctors still cannot predict which patients are at risk of developing cognitive problems, however, because there is too much variation among individuals.
The study, conducted with Michael Basso of the University of Tulsa and published in a recent issue of the Journal of Clinical and Experimental Neuropsychology, followed 200 homosexual men over a six-month period.
Seventy-four of the men tested positive for HIV but showed no symptoms of disease, 31 were HIV positive and had early signs of disease, 23 had AIDS-defining illnesses, and 10 were diagnosed with AIDS because they had CD4 cell counts below 200/mm3 (CD4 cells are the immune cells that are destroyed in the course of HIV disease). These groups were compared to a control group of 62 matched men who were not infected with HIV.
AIDS-defining illnesses are those that were identified by the Centers for Disease Control and Prevention (CDC) as indicative of severe immune suppression and diagnostic of AIDS in their own right. They include such diseases as Kaposi's sarcoma, Pneumocystis pneumonia, and candidiasis of the lung and airway.
Study participants were given baseline tests for attention, dexterity, and verbal learning and recall. Participants were tested again six months later.
No differences were found in attention or dexterity after 6 months, but in learning and recall, the group with AIDS-defining illnesses did significantly more poorly than all other groups.
The researchers speculated that no differences were found in attention and dexterity because the six-month time interval between testing may have been too brief to reveal differences. Verbal learning and recall, however, are both important for complying with complex treatment regimens.
The men involved in the study were tested between 1991 and 1996, prior to the use of protease inhibitors, a class of drugs that are now commonly used in combination with other antiretroviral drugs to treat people with HIV disease and AIDS.
"The therapeutic options and medication regimens that are available today will almost certainly change the impact of this," said Bornstein. "But there are still lots of people who are infected with HIV and who remain untreated, and many are now living long after they are diagnosed with AIDS because of the new therapeutic options."
Bornstein suggests that physicians who are treating people with HIV should stay alert for signs of emerging cognitive deficit in their patients, particularly in patients with AIDS-defining illnesses. Bornstein, who has been studying people with HIV since 1989, is now working to identify specific factors that increase a person's risk of developing dementia and factors that may influence the course of decline.
This research was funded by grants from the National Institute of Mental Health, the National Institute on Alcohol Abuse and Alcoholism, and the National Institute on Drug Abuse.