Cognitive changes in HIV and AIDS infection
Among the primary neurological complications of AIDS are cognitive deficits such as HIV-associated dementia and milder forms, such as minor cognitive / motor disorder, both of which can alter the activities of daily living and reduce the quality of life of patients. HIV-1 infection is the most common, predictable and treatable cause of cognitive deficits in individuals under 50 years of age. Despite advances in knowledge of clinical characteristics, pathogenesis, neurobiological aspects and the widespread use of highly active antiretroviral therapy (HAART, or ART), neurological complications and cognitive deficits still persist, leading to serious personal and socio-economic consequences, great therapeutic challenge. In the pre-HAART era, dementia was a common complication of infection, however in the HAART era the incidence of dementia has decreased, but the prevalence has increased mainly in the milder forms due to the increase in the number of infected people and the increase in life expectancy . Cognitive changes associated with HIV are typically subcortical and may be associated with behavioral and motor impairments. These syndromes are clinically diagnosed, and neuropsychological tests, neuroimaging and cerebrospinal fluid corroborate the diagnosis. This review updates the current state of epidemiology, clinical characteristics and diagnosis of cognitive complications in the course of HIV infection.
Since its recognition in the early 80s, the Acquired Immunodeficiency Syndrome (AIDS) has spread across the world, becoming one of the greatest public health challenges of the last three decades.
The World Health Organization (WHO) estimates that approximately 33,2 million people worldwide are infected with the HIV virus or have the disease and that in 2007 there were 2,1 million deaths and about 2,5 million new ones. cases1.
In Brazil, since the identification of the first AIDS patient in 1982, until June 2007, approximately 474 thousand cases of the disease have been identified. It is estimated that approximately 593 thousand people are currently living with HIV or AIDS and, according to WHO parameters, the prevalence of HIV infection is 0,61% among the population aged 15 to 49 years, with 0,42% among women and 0,80% among men2.
In the first cases, the severe and progressive immunological impairment of HIV-infected patients was very evident, particularly their cellular immunity. This fact ended up predisposing them to neoplasms and infections, most of them opportunistic and these in particular always brought high morbidity and mortality for AIDS patients, being markers of the syndrome.
Alongside the lymphoid system, the Central Nervous System (CNS) is an important target for HIV and the virus has been frequently detected in cerebrospinal fluid (CSF) and brain tissue since the beginning of the infection and throughout its evolution, regardless of have neurological symptoms3. The virus infects and replicates in macrophages, microglia and multinucleate glial cells, but is mainly free and present in the acellular cerebrospinal fluid 4.
The CNS is the second most common site of clinical manifestations. This can be explained by the fact that the virus is neurotropic and the CNS is a “sanctuary” for him, in addition to the poor penetration of antiretroviral drugs in the presence of an intact blood-brain barrier.5.
Neurological manifestations affect 40% to 70% of HIV patients in the course of their infection67, and in necropsy studies, the frequency can reach more than 90%8. About 46% of patients hospitalized with AIDS may have neurological disease, either as the main reason for hospital admission or as complications during hospitalization 9
The nature of neurological changes is very varied and any part of the neuroaxis can be affected. The most important determinant of susceptibility is the degree of immunosuppression. The differential diagnosis is broad and involves infectious, neoplastic, cerebrovascular, toxic-metabolic, nutritional etiologies,
autoimmune and related to the virus itself such as neuropathies, myelopathies and cognitive changes. Associations of etiologies may also occur in the same patient, which is a peculiarity of the immunocompromised person.
In the course of HIV infection, the virus enters the CNS and may result in disorders of cognitive function causing deficits in mental processes, such as attention, learning, memory, speed of information processing, ability to solve problems and sensory and motor symptoms.
Recent advances in the treatment of HIV infection have increased the life expectancy of patients making it more likely that doctors and psychologists will find patients with neuropsychiatric manifestations of the disease in daily clinical practice.
The most common neurological manifestations, directly linked to HIV, are cognitive and minor motor disorder and HIV-associated dementia. In Brazil, sequelae related to CNS opportunistic diseases, such as neurotoxoplasmosis, tuberculous meningitis and neurocriptococcosis, are also important causes of cognitive and psychiatric damage. Therefore, the correct and early diagnosis of these conditions and the prompt therapeutic intervention can minimize neuropsychiatric complications.
It is of great importance to quantify the number of patients with cognitive impairments, since they affect quality of life, work function and adherence to highly active antiretroviral therapy (HAART) 10,11. Cognitive damage is associated with increased risk of mortality, increased risk of developing dementia and high unemployment rates and this occurs even in the HAART era