Future HIV treatment could be more accurate due to a new discovery which utilises MRI scans.
Scientists at Northwestern University and North Shore University Health System used the machines to test the brain activity of a group of patients who had been infected for less than one year and compared the results to a control group of healthy people.
Researchers found "prominent changes" of the functional connectivity in the visual networks of the HIV patients.
Diminished cognitive functions affect around 50 per cent of sufferers and can impair a range of sensory functions such as memory, attention and verbal capabilities.
"These findings indicate that changes in brain function are occurring very early in HIV infection and subclinical alterations in functional connectivity may reflect vulnerability to cognitive decline," said Ann Ragin, the principal investigator from Northwestern University Medical School.
According to the Aids charity Avert, 86,500 people were living with the disease in the UK at the end of 2009.