Beau Nakamoto

Neurologist Beau Nakamoto, associate professor of medicine at the John A. Burns School of Medicine, received a two-year, $421,313 grant from the National Institute of Neurological Disorders and Stroke (National Institutes of Health) to examine whether a new magnetic resonant imaging (MRI) contrast dye can be used to detect the inflammation that is believed to signal decline in memory and thinking. The contrast dye that Nakamoto will be studying will specifically target the immune system’s white blood cells, which are believed to play a key role in the development of HIV-associated cognitive impairment.

About 2,900 people in Hawaiʻi live with HIV/AIDS, and there continue to be new cases every year. In the last two decades, as people live longer under a daily regimen of anti-viral HIV-fighting medicine, the Hawaiʻi Center for AIDS has noticed that HIV patients are suffering dementia at rates greater than people without the virus.

While severe HIV dementia is uncommon with effective combination antiretroviral therapies, milder degrees of cognitive impairment continues to affect up to 50 percent of HIV-infected individuals. Even mild cognitive impairment can have a big impact on important parts of a person’s daily life. Employment difficulties arise because of fatigue, driving is difficult or dangerous and people forget to take their medications (without daily doses of life-sustaining HIV antivirals, HIV patients will die).

An MRI image of the brain before (A) and after (B) novel MRI dye infused. Magnified image (C) after the MRI dye is infused demonstrates accumulation of the MRI dye along the vessel wall in the brain (arrow). It is hypothesized that this may represent inflammation from the cells involved in cognitive impairment in HIV-infected patients.

Nakamoto, a neurologist at Straub Clinic and Hospital, is a member of an elite team of researchers at the Hawaiʻi Center for AIDS who suspect one of the main types of cells which protect the body against infection also play a key role in causing HIV-associated dementia. It is believed that once these infection-fighting cells (monocytes) have switched on to battle HIV, an unintended consequence is the production of toxic chemicals in the brain that cause uncontrolled inflammation and ultimately cognitive impairment.

Nakamoto is one of few researchers in the nation to utilize novel MRI contrast agents to track those infection-fighting cells in the brains of HIV-infected patients. If successful, this technique could potentially be used in future clinical trials aimed at targeting the HIV-infection fighting monocytes with the hope of finding a treatment for HIV-associated dementia.