Scans could be used to spot patients who might benefit from brain-protecting drugs, the authors told Proceedings of the National Academy of Sciences.

HIV experts said more work was needed to check that neuroprotective drugs would be beneficial to Aids patients and that these treatments would not be safe to take alongside the powerful anti-HIV drugs such individuals are already on.

As drugs improve, people with HIV/Aids are living much longer.

However, at least two in five living with HIV/Aids will suffer from cognitive impairments, ranging from minor deficits to dementia, studies suggest.

While researchers are aware of this, the pattern of damage the virus causes in the brain has not been well understood.