HIV and AIDS affected approximately 36,900,000 people worldwide in 2017.1 HIV, which stands for human immunodificiency virus, is found in and spreads through bodily fluids.2,3 If left untreated, HIV is easily spread and continuously attacks the body's immune system, causing an increase in illnesses. The virus affects people of all ages including children, most of whom may develop it while in the womb, during childbirth or while being breastfed. Unfortunately, HIV cannot be cured, but the progression of the disease can be halted with the use of antiretroviral therapy (ART). HIV has three stages, which have varying levels of severity and outcomes: acute HIV infection, clinical latency, and AIDS (acquired immunodefiency syndrome).
The stages of HIV
During the stage of acute HIV infection, patients begin showing symptoms within two to four weeks after initial infection.2,3 These symptoms often are similar to those of the flu, and it is important for patients to be screened if they are concerned about having contracting HIV. Starting treatment early on in this period can have significant benefits, since large amounts of the virus are being produced throughout the body. Early treatments can also prevent a high transmission rate during this first stage.
During the second stage, clinical latency, the virus remains active but reproduces at a much lower rate.2,3 People who are compliant with their treatment may be in this stage for decades, though those who aren't compliant or do not take any form of ART are typically in this stage for a decade or less. HIV is still transmittable at this point, even though outward symptoms do not persist. The virus continues to attack and weaken the immune system and increase the possibility of contracting other illnesses. By the end of clinical latency, the virus decreases the CD4 count in a patient's blood.
The final stage of HIV is AIDS. Patients' immune systems are terribly damaged, and they may develop a number of opportunistic illnesses.2,3 This stage is characterized by levels of CD4 below 200 cells/mm or the development of certain opportunistic illnesses. The average untreated AIDS patient will survive for 3 years and is highly infectious.Therefore, it is extremely important to detect HIV early on.
MRI for monitoring HIV and AIDS
HIV causes inflammation in the brain in as little as four months after infection.4,5 Medications used to treat HIV and illnesses caused by the virus can cause further neurological problems. These problems include brain swelling and, most commonly, dementia. Some of the neurological disorders require aggressive therapy while others are treated symptomatically.
In 2017, it was discovered that HIV does directly affect the brain.6 A group of functional MRI (fMRI) scans showed that there was a notable decrease in the blood flow to the brain in patients with HIV when performing tasks involving higher motor function. These patients had not yet started on ART. Additionally, the HIV patients had a decrease in blood flow to areas of the brain associated with motivation.
If neurological problems persist while taking ART's, doctors originally had to draw spinal fluid to test for the HIV virus.7 The viral concentration decreases during the clinical latency phase, meaning that very little to no HIV cells should be found in the spinal fluid. The procedure to draw spinal fluid and test it required patients to remain in the hospital for a few hours.
A retrospective study of 146 patients who presented with HIV found that there were neurological signs of persistent HIV during treatment with ART.7 In these patients, MRI showed the atrophy cause by HIV-induced dementia has a correlation with the concentration of HIV in cerebro-spinal fluid. Atrophy shows up on MRI as diffuse white matter abnormalities, or widespread changes in brain tissue and brain tissue structures. MRI provides a non-invasive way to monitor HIV spread to the brain during the clinical latency phase and, therefore, does not require time in the hospital outside of the exam.
MRI can be used to measure and monitor the effects of HIV on the brain, especially in terms of decreased motivation and increased atrophy. This allows doctors to check for build-up of the HI virus. With as many people, including children, going through the three phases of HIV (acute HIV infection, clinical latency, and AIDS) every day, a non-invasive technique to monitor the virus and determine long-term outcomes is necessary.
1. "Global Statistics." UNAIDS. 20 November 2018. Web. 28 November 2018. <https://www.hiv.gov/hiv-basics/overview/data-and-trends/global-statistics>.
2. "What are HIV and AIDS?" HIV.gov. 15 May 2017. Web. 28 November 2018. <https://www.hiv.gov/hiv-basics/overview/about-hiv-and-aids/what-are-hiv-and-aids>.
3. "About HIV/AIDS." CDC.gov. 31 October 2018. Web. 28 November 2018. <https://www.cdc.gov/hiv/basics/whatishiv.html>.
4. "Neurological Complications of HIV." Johns Hopkins Medicine. Web. 28 November 2018. <https://www.hopkinsmedicine.org/healthlibrary/conditions/nervous_system_disorders/neurological_complications_of_hiv_134,46>.
5. "Neurological Complications of AIDS Information Page." NINDS.NIH.gov. 20 June 2018. Web. 28 November 2018. <https://www.ninds.nih.gov/Disorders/All-Disorders/Neurological-Complications-AIDS-Information-Page>.
6. Stellenbosch University. "HIV directly impacts the brain in the eaarly stages of the infection, report researchers." ScienceDaily. 30 November 2017. Web. 28 November 2018. <https://www.sciencedaily.com/releases/2017/11/171130112412.htm>.
7. Ruthiran Kugathasan, et al. "Diffuse White Matter Signal Abnormalities on Magnetic Resonance Imaging Are Associated With Human Immunodeficiency Virus Type 1 Viral Escape in the Central Nervous System Among Patients With Neurological Symptoms." Clinical Infectious Diseases. 15 April 2017; 64(8): 1059-1065. Web. 28 November 2018. <https://academic.oup.com/cid/article/64/8/1059/3055688>.