Dementia due to HIV Disease

Clinical Features

Patients with AIDS dementia present with impairments of cognitive, behavioral, and motor systems.

• The cognitive disorders include memory impairment, confusion, and poor concentration.
• Behavioral features include apathy, reclusivity, anhedonia, depression, delusions, and hallucinations.
• Motor symptoms include incoordination, lower-extremity paresis, unsteadiness, and difficulty with fine motor movements like handwriting and buttoning clothes.

As the disease progresses, parkinsonism and myoclonus develop.

Localizing signs such as tremors, focal seizures, abnormal reflexes, and hemiparesis can result. The protozoan Toxoplasma gondii commonly infects the CNS and can be diagnosed by CT or by increased toxoplasmosis antibody titers.

Discrete cerebral lesions are also produced by fungi such as Candida and Aspergillus, Mycobacterium tuberculosis, and viruses such as cytomegalovirus and papovavirus.

Papovavirus causes progressive multifocal leukoencephalopathy. Tertiary syphilis has increased significantly since the advent of AIDS, and neoplasms such as lymphomas, metastatic Kaposi’s sarcoma, and gliomas are also causes of AIDS dementia.

Many confounding factors can increase cognitive dysfunction in AIDS, including a high incidence of abuse of drugs and alcohol; medications such as histamine H₂ receptor antagonists (cimetidine), corticosteroids, narcotics, and antiviral drugs (e.g. zidovudine (formerly azidothymidine, AZT)) that increase confusion; and coexistent depression.

The CT scan shows cerebral atrophy and MRI reveals nonspecific white matter abnormalities. Neoplasms and lesions such as toxoplasmosis are also visible. Lumbar puncture reveals a pleocytosis and elevated protein levels, and autopsy demonstrates an atrophic brain with demyelination, multinuclear giant cells, and gliosis of the cerebral cortex.

Treatment

The treatment of neuropsychiatric disorders in AIDS involves utilizing agents that are least likely to interfere with other medications prescribed, or to exacerbate the symptoms of the disease. AIDS-related depression has responded well to SSRIs and to psychostimulants.

Some HIV drugs can have interactions with SSRIs, particularly ritonavir and the SSRIs themselves, especially paroxetine and floxetine, can interact with other agents the HIV patient may have been prescribed, such as antiarrhythmics, benzodiazepines, and anticonvulsants, by inhibiting the cytochrome P-450 enzyme system.

Careful attention to drug-drug interactions, using lower starting doses of certain psychiatric drugs, and monitoring the blood levels of affected medications are recommended. Among the psychostimulants, methylphenidate is preferred to dextroamphetamine, because of the latter’s tendency to produce dyskinesias. Treating patients with a history of abusing stimulants is not recommended.

Anticholinergic agents have a number of side effects such as mydriasis, decreased gastrointestinal motility, and postural hypotension; however, low-dose tricyclic antidepressants are often used for their sedative, analgesic, and appetite-stimulant properties.