What is HIV-1 Encephalopathy and Aids Dementia Complex?
Between 4% to 15% of people diagnosed with HIV report symptoms like memory loss, difficulty concentrating and paying attention, and problems with motor skills. It’s important to point out that these symptoms are quite common in many disorders, so an accurate diagnosis is crucial for proper and effective treatment. HIV can also affect the brain, leading to what was first named AIDS Dementia Complex (ADC) in 1986. ADC was a common occurrence in the HIV disease before the widespread use of antiretroviral therapy in the mid-90s.
Patients with HIV can also suffer from other issues that can affect brain function, such as mood disorders, post-traumatic stress disorder, and substance abuse. There can also be increased risks from infections, tumors, and side effects of antiretroviral drugs. Also, it’s worth noting that patients can experience symptoms ranging from confusion during the early stages of the HIV disease to dementia during the later stages.
In 2007, what was formerly known as ADC was reclassified as HIV-associated neurocognitive disorders (HAND). HAND is a spectrum of worsening brain and cognitive symptoms, and it can be classified into three levels of severity: asymptomatic neurocognitive impairment (not showing symptoms but impairment can be detected in tests), minor neurocognitive disorder, and HIV-associated dementia. The level of severity is determined by observing the patient and carrying out neuropsychological tests. It’s important, however, that the symptoms aren’t being caused by any other factors such as other infections, cerebrovascular disease, or toxic encephalopathy (damage to the brain due to exposure to toxic substances). In day-to-day medical care, distinguishing between the less severe categories can be challenging because it requires neuropsychological testing. But when a person has severe symptoms and is not functioning well, and especially if they have untreated or advanced stage AIDS, HIV-associated dementia can be presumed.
What Causes HIV-1 Encephalopathy and Aids Dementia Complex?
The connection between HIV infection and the noticing of problems with things like memory, attention, and problem-solving skills isn’t completely clear. However, it is believed to be due to several things. For one, proteins that come from virus genes in infected cells can harm nerve cells, or neurons directly.
In addition, certain molecules (called cytokines) made by activating the immune response in the surrounding healthy brain cells (also known as glial cells), may also lead to these neurons being damaged. Plus, our immune system produces substances called antibodies that can attack parts of our own body. Some of these ‘autoantibodies’ that attack brain tissue have been found in HIV-infected patients who are suffering from HIV-Associated Dementia (HAD). Interestingly, these autoantibodies seem to be less common in HIV-infected people who do not develop this type of dementia.
These autoantibodies can still be found in a patient’s cerebrospinal fluid (a fluid found in the brain and spine) even after they have started treatment for HIV. This could shed light on why some symptoms can continue to develop in patients with low amounts of the virus present in their bloodstream.
Risk Factors and Frequency for HIV-1 Encephalopathy and Aids Dementia Complex
Neuropsychological tests can reveal slight cognitive impairments in as much as 40% of the HIV-infected patients who are treated with antiretrovirals. Studies from around the world generate different estimates for the occurrence of HIV-associated dementia (HAD), but all indicate a decline since the introduction of antiretroviral therapy (ART). The prevalence of HIV-associated neurological disorders (HAND) seems to follow the same pattern as HIV infection, rising with age and occurring in both genders and all races.
- Neuropsychological tests can show minor cognitive issues in up to 40% of HIV-infected patients on antiretrovirals.
- A Danish study found that 1 in 1000 untreated patients with low CD4 counts would progress to HAD.
- The European CASCADE study found a HAD incidence of 0.66 per 1000 person-years, a tenfold decrease from pre-ART times.
- The US CHARTER study estimated a HAD incidence of 10.5 cases per 1000 patient-years, down from 21 cases per 1000 patient-years before ART therapy.
- The occurrence of HAND appears to rise with age and is similar across races and genders, much like HIV infection.
Signs and Symptoms of HIV-1 Encephalopathy and Aids Dementia Complex
To check for risks of HIV-related dementia, it’s important to review someone’s health history and carry out a physical check-up to rule out other causes of dementia. Certain factors can increase the risk, including low CD4 cell count, a late diagnosis of HIV, long-term HIV infection, and past diagnosis as having AIDS. It’s crucial to know if someone consistently takes their prescribed medication, attends medical check-ups, and their current status with HIV disease treatment. Understanding the timeline of symptoms and level of disability is also key. Other issues like past head injuries, drug abuse, or mental health conditions that might cause cognitive problems should be noted. Changes in mood, memory loss, difficulty sleeping, weight loss and lack of interest are common in these patients.
In the case of mild cognitive issues, patients may not complain about anything specific. When an individual is at risk for HIV-related dementia or has a low CD4 count, a cognitive test should be performed routinely. The signs that help clinicians separate patients may include less emotional expression, and issues with speaking fluently, making decisions, performing tasks, and memory. Advanced brain functions like using language, recognising objects or performing learned movements might be lost in the late stages of the disease. In serious cases, patients may show signs of brain overactivity and difficulty with quick alternating movements. Through a neurologic exam, assessing their level of alertness is important; it’s noteworthy that HIV-related dementia generally does not alter consciousness. These tests can also identify signs of other neurological illnesses, like Parkinson’s disease, stroke, brain tumors, or progressive multifocal leukoencephalopathy.
Testing for HIV-1 Encephalopathy and Aids Dementia Complex
To figure out what might be causing a patient’s cognitive decline or confusion, doctors recommend different diagnostic tests. These tests help rule out other diseases affecting the brain, such as infections, nervous system disorders, mental health issues, or conditions caused by toxins. Depending on the person’s symptoms, the doctor may order tests for liver function, blood sugar levels, Vitamin B12 levels, thyroid hormone levels, syphilis, and hepatitis.
The progression of HIV can get assessed by measuring the CD4 count in the blood, which is a type of white blood cell that HIV destroys, and the HIV viral load, which is the number of copies of the virus in the blood. These tests will help the doctor understand the stage of HIV infection.
Imaging tests, like MRI (Magnetic Resonance Imaging), can get ordered to check for any diseases affecting the nervous system or any stroke-related (cerebrovascular) conditions. People with HIV often experience widespread brain shrinkage, affecting areas involved in learning, coordination, and complex thinking. In severe cases, an electroencephalogram, a test that records electrical activity of the brain, may show a slowing down in brain wave patterns.
Another diagnostic test could involve taking a sample of cerebrospinal fluid (CSF), which is the clear fluid found in the brain and spine that carries nutrients and removes waste products. The CSF test can reveal increased viral load, suggesting the presence of a virus, an unusual number of lymphocytes (a type of white blood cell), or increased protein levels. These findings are common, meaning they don’t pinpoint a specific cause. Additional CSF tests may check for specific infections such as toxoplasmosis, cryptococcus (a type of fungus), syphilis, or various viruses such as the John Cunningham (JC) virus, Epstein-Barr virus (EBV), and cytomegalovirus (CMV).
Treatment Options for HIV-1 Encephalopathy and Aids Dementia Complex
Treatment and prevention of HAND (HIV-associated neurocognitive disorders) largely rely on sticking to ART (antiretroviral therapy). This is a type of treatment for HIV that can help improve brain function in patients diagnosed with serious deficits. Over time, the chance of developing severe HAND has decreased thanks to ART becoming more common. If an untreated HIV patient starts to show signs of declining brain function, they should begin ART straight away. The type of ART used should be chosen carefully, depending on factors such as the patient’s viral load (amount of HIV in the blood), genetic factors influencing their HIV, potential for drug interactions, and any other health conditions the patient has.
However, it’s less clear how well ART can prevent the milder forms of HAND, namely MND (Mild Neurocognitive Disorders) and ANI (Asymptomatic Neurocognitive Impairment). These are often subtle, meaning they could be overlooked and hence underdiagnosed. It’s also uncertain if any particular ART medicines are better than others at preventing the progression of brain function decline. One medicine to potentially avoid is efavirenz, as it can cause side effects that could interfere with brain function testing. For patients on an effective ART regimen with a low viral load and high CD4 levels (a type of white blood cell that helps fight infection), any further decline in brain function is more likely to be due to other causes. It’s important that other diseases or conditions are ruled out through appropriate examination.
If a patient has any psychiatric comorbidities (additional mental health disorders), they should be diagnosed and treated as necessary based on a psychiatric evaluation.
What else can HIV-1 Encephalopathy and Aids Dementia Complex be?
When trying to diagnose HIV-1 encephalopathy and AIDS dementia complex, doctors must rule out numerous possible conditions that might cause similar symptoms. Some of these other possible diagnoses include:
- Central Nervous System (CNS) infections, especially common in people with a low CD4 count who are not taking antibiotics. Infections to look out for include herpes simplex, varicella-zoster, CMV, EBV, JC, toxoplasmosis, syphilis, and Cryptococcus.
- Cancer, such as CNS lymphoma and other types that may have spread to other parts of the body (This would usually be identified on brain imaging).
- Other types of dementia, like Parkinson’s, Alzheimer’s, Lewy Body disease, and dementia affecting the frontal and temporal lobes. Keep in mind that the risk of these types of dementia is higher due to the increased life expectancy of the general HIV-infected population.
- Endocrine disorders like adrenal insufficiency or hypothyroidism.
- Substance use or acute intoxication.
- Delirium.
Nutritional issues can also lead to cognitive impairment. For example, a deficiency in vitamin B12 can lead to cognitive impairment, paresthesia (tingling sensation), and sensory problems. Drug effects or acute intoxication can also be responsible.
What to expect with HIV-1 Encephalopathy and Aids Dementia Complex
HIV-associated dementia (HAD) is a condition that, without antiretroviral therapy (ART, a treatment for HIV), often results in a short lifespan of 3 to 6 months. But with the introduction of ART in the 1990s, the average survival period has improved to 38.5 months. It’s also believed that with continued use and adherence to a more advanced form of ART known as HAART, the average lifespan should be similar to the average person living with HIV.
However, some factors can worsen the outlook for individuals with HIV-associated dementia. These include a less educated background, being older in age, having a lower count of CD4 (a type of white blood cell that fights infection), higher HIV viral load (amount of virus in the blood), decreased levels of blood components like hemoglobin and platelets, lower body mass, having a hepatitis C infection at the same time, use of intravenous drugs, and poor adherence to medication.
Additionally, the presence of HIV-associated dementia itself is a separate factor that increases the risk of death in people living with HIV.
