Pharmacological frontiers in the treatment of AIDS dementia

Alzheimer's and non-alzheimer's dementia: a critical review of pharmacological and nonpharmacological strategies

OBJECTIVE

Dementia is an age-related progressive neurodegenerative disorder afflicting about 5% of the world's population, and it is expected to grow dramatically in the future keeping in view our ageing society. Currently available medications appear to be able to produce moderate symptomatic benefits but do not to stop disease progression. In this article, the management of the disorder, including the currently available drugs as well as psychosocial strategies, is discussed.

METHODS

A computerized search on Pubmed from 1980 to 2006 was carried out and all articles evaluated and graded on NICE guidelines.

RESULTS AND CONCLUSIONS

Currently evaluated and accepted medications only bring about a reduction in the deteriorating course. A combination of pharmacotherapy and psychosocial management is the need of the hour.

HIV-1 infection of neurons might account for progressive HIV-1-associated encephalopathy in children

Direct and productive infection of neurons in vivo is still a matter of debate, although in vitro experiments have demonstrated that immature neuronal cells can be productively infected by various human immunodeficiency virus (HIV) strains. To address this controversy we have analyzed, using light microscopy and in situ hybridization (ISH), HIV-1 infected cells in brain tissue from four pediatric cases of HIV-1-associated encephalopathy (EP). HIV-1 RNA-expressing cells--therefore, actively infected cells--were detected by ISH in different amounts in all brain specimens from the four children. They mainly correspond to glial cells. However, in two of the four children, who had severe progressive EP, but not in the other two, who had the static form, HIV-1-infected neurons were clearly observed in the cortical brain samples. These results provide initial evidence that HIV-1 can actively infect neurons in vivo in children and show a cortical involvement of HIV brain infection in clear correlation with the clinical EP symptoms.

A five-year evaluation of reports of overdose with indinavir sulfate

PURPOSE

To describe the adverse event profile for indinavir sulfate overdose.

METHODS

Analysis of indinavir overdose reports in Merck & Co., Inc.'s safety database through the first 5 years following US licensure of indinavir. Reports were classified as acute (single high dose in excess of 2400 mg), chronic (multiple extra doses, not exceeding 2400 mg per dose), single extra dose (not exceeding 2400 mg) and dose not reported.

RESULTS

Seventy-nine reports of indinavir overdose were reviewed (15 acute, 43 chronic, 13 single extra dose and 8 dose not reported). A total of 52/79 (66%) reports were associated with adverse events. For acute overdose reports with adverse events, indinavir doses ranged from 2.8 g to 48 g (median 6 g; mean 13 g); for acute overdose reports without adverse events, indinavir doses ranged from 4 g to 80 g (median 56 g; mean 45 g). Adverse events following acute and chronic exposures were similar; the most commonly reported adverse events included nausea, vomiting, abdominal pain and nephrolithiasis. Of the 52 patients with adverse events, 39 recovered, 6 had not recovered at the time of reporting and no information regarding outcome was provided in 7 reports.

CONCLUSIONS

Overdose with indinavir was associated with adverse events in the majority of reports. These were most commonly gastrointestinal and renal events, and were generally consistent with the known safety profile of indinavir. The majority of patients recovered.

Severe, demyelinating leukoencephalopathy in AIDS patients on antiretroviral therapy

OBJECTIVES

To describe a severe form of demyelinating HIV-associated leukoencephalopathy in AIDS patients failing highly active antiretroviral therapy (HAART), its relationship to clinical and neuroimaging findings, and suggest hypotheses regarding pathogenesis.

DESIGN AND METHODS

AIDS patients who failed HAART and displayed severe leukoencephalopathy were included. All cases had detailed neuromedical, neuropsychological, neuroimaging and postmortem neuropathological examination. Immunocytochemical and PCR analyses were performed to determine brain HIV levels and to exclude other viruses.

RESULTS

Seven recent autopsy cases of leukoencephalopathy in antiretroviral-experienced patients with AIDS were identified. Clinically, all were severely immunosuppressed, six (86%) had poorly controlled HIV replication despite combination antiretroviral therapy, and five (71%) had HIV-associated dementia. Neuropathologically, all seven had intense perivascular infiltration by HIV-gp41 immunoreactive monocytes/macrophages and lymphocytes, widespread myelin loss, axonal injury, microgliosis and astrogliosis. The extent of damage exceeds that described prior to the use of HAART. Brain tissue demonstrated high levels of HIV RNA but evidence of other pathogens, such as JC virus, Epstein-Barr virus, cytomegalovirus, human herpes virus type-8, and herpes simplex virus types 1 and 2, was absent. Comparison of the stages of pathology suggests a temporal sequence of events. In this model, white matter damage begins with perivascular infiltration by HIV-infected monocytes, which may occur as a consequence of antiretroviral-associated immune restoration. Intense infiltration by immune cells injures brain endothelial cells and is followed by myelin loss, axonal damage, and finally, astrogliosis.

CONCLUSIONS

Taken together, our findings provide evidence for the emergence of a severe form of HIV-associated leukoencephalopathy. This condition warrants further study and increased vigilance among those who provide care for HIV-infected individuals.

Preclinical psychopharmacology of AIDS-associated dementia: lessons to be learned from the cognitive psychopharmacology of other dementias

Following a brief discussion of the epidemiology, underlying neuropathological mechanisms, neuropsychological symptoms and present treatment strategies of AIDS-associated dementia (AAD), parallels are drawn between the longer standing research on drugs for the treatment of other cognitive disorders, particularly senile dementia, and ongoing efforts to develop psychopharmacological approaches for the treatment of the cognitive impairments in AAD. Important aspects of hypotheses designed to guide such a research are indicated with the help of a speculative, paradigmatic hypothesis concerning the role of cortical cholinergic inputs in AAD. Furthermore, aspects of validity of animal models, and cognition as a crucial intervening variable in the effects of potential treatments, are evaluated.

CPI-1189 attenuates effects of suspected neurotoxins associated with AIDS dementia: a possible role for ERK activation

Individuals infected with the human immunodeficiency virus (HIV) often experience a dementia characterized by mental slowing and memory loss. Motor dysfunction may also accompany this condition. The pathogenesis of the dementia is not known, but microscopic examination of brain tissue from those afflicted shows evidence of chronic inflammation, reactive gliosis and cell death. Neurotoxic factors produced from activated macrophage or microglial cells such as tumor necrosis factor-alpha (TNFalpha), gp120 and quinolinic acid have been implicated as agents for the cell death which often appears to occur by an apoptotic mechanism. CPI-1189, a drug currently undergoing clinical evaluation as a treatment for the dementia associated with AIDS, is shown in this paper to mitigate apoptosis induced by TNFalpha, gp120, and necrosis induced by quinolinic acid. In addition, CPI-1189 mitigates the cell death produced by supernatants from cultured macrophages obtained from patients with AIDS dementia. The exact mechanism by which CPI-1189 prevents neurotoxicity is not known; however, protection from TNFalpha and supernatant-induced toxicity does not appear to involve NFkappaB translocation, and appears to be associated with an increase in activated ERK-MAP kinase. These findings may have implications for other neurological diseases where apoptotic cell death contributes to neurodegeneration.