Dementia and sensory neuropathy are common among untreated HIV-positive individuals in sub-Saharan Africa, according to research presented this week at the American Academy of Neurology 56th Annual Meeting in San Francisco. Half of all HIV-positive patients presenting at an infectious disease clinic in Uganda had sensory neuropathy.
"Two-thirds of all HIV-positive individuals -- some 26.6 million individuals -- live in the countries of sub-Saharan Africa," said lead study author Matthew Wong of McMaster University in Ontario. "Despite these large numbers, the frequency of neurological complications of HIV infection in this population is largely unknown." In the United States, dementia is seen in 10-15 percent of HIV-positive patients, and sensory neuropathy in 30 percent.
To determine the corresponding rates in sub-Saharan African populations, Wong and colleagues performed detailed neurological, neuropsychological, and functional assessments on 53 HIV-positive and 31 HIV-negative individuals at an infectious diseases clinic in Uganda.
Dementia was present in 11 percent of all HIV-positive patients. Within the subgroup whose CD4 counts were below 200, dementia was present in 50 percent. A CD4 count below 200 is the standard threshold for initiating anti-retroviral therapy in resource-limited settings.
Painful sensory neuropathy was diagnosed in 51 percent of HIV-positive patients, and neurological signs of aberrant nerve function were seen in 38 percent. HIV-positive patients were also approximately 25 percent more functionally impaired than HIV-negative patients, and showed decreased abilities on tests of verbal recall, psychomotor speed, and motor performance.
"HIV-positive individuals with advanced infection have impaired verbal memory, motor, and functional performance compared to HIV-negative individuals," said Wong. He also suggested that the International HIV Dementia Scale, used in this study, may be a useful rapid screening test for HIV dementia in the developing world, since it can be performed quickly by non-neurologists without special equipment.
The incidence of peripheral neuropathy identified in this small study needs to be confirmed by larger natural history studies, but if borne out by other studies it raises awkward questions about the use of d4T (stavudine) in first-line treatment in resource-limited settings. Peripheral neuropathy caused by HIV disease is worsened by d4T and by the combination of d4T and ddI, especially if the drugs are dosed at inappropriately high levels for body weight.
Individuals with a body weight below 60kg should receive a d4T dose of 30mg twice daily and if neuropathic pain develops, the World Health Organisation recommends in its treatment guidelines that d4T should be stopped and AZT (zidovudine) should be substituted, since it will not cause peripheral neuropathy.