THE EDINBURGH COHORT OF HIV-POSITIVE INJECTING DRUG-USERS AT 10 YEARSAFTER INFECTION - A CASE-CONTROL STUDY OF THE EVOLUTION OF DEMENTIA

Objective: To examine the evolution of dementia in HIV-positive inject ing drug users (IDU) in Edinburgh. Design: Case-control study. Partici pants: Twenty six (6%) out of 404 patients in the Edinburgh cohort of HIV-positive IDU who have developed HIV-1-associated dementia in the 1 0 years since infection and seroconversion. Methods: Patients were tes ted repeatedly, where possible, on a range of neuropsychological and n europhysiological measures. The results from patients with dementia we re compared with those of age, sex and Iq-matched non-demented HIV-pos itive controls from the cohort. An auditory event-related potential (P 3 or P300), a neurophysiological measure of cognitive function, detect ed the onset of a marked slowing of cognitive and psychomotor function s. Neuropsychological measures that involve the speed of information p rocessing such as the Trail-Making task also identified the early stag es of dementia. Results: Dementia was associated with a more advanced stage of systemic disease, increased rates of decline in CD4 cell coun ts and markedly reduced survival compared with the non-demented contro ls. No evidence for a protective effect of treatment with zidovudine w as detected. Conclusion: In the first 10 years after infection with HI V-1 dementia is an individual development, not the clinical extreme of general intellectual impairment, and had occurred in at least 6% of o ur IDU cohort. Future questions concern the long-term rate of dementia , the critical neuropathological change and the true potential for ear ly treatment.