Common Comorbidities with Substance Use Disorders Research Report
Part 3: The Connection between Substance Use Disorders and HIV

More than 1.2 million people in the United States are living with human immunodeficiency virus (HIV), the virus that causes acquired immune deficiency syndrome (AIDS).114 HIV is transmitted through contact with infected blood and bodily fluids. Such contact can occur through unprotected sex, through sharing needles or other drug injection equipment, through mother-to-child transmission during pregnancy or breastfeeding, and through infected blood transfusions and plasma products. While effective antiretroviral therapy (ART) is available, there is currently no cure for HIV/AIDS.115,116 However, the provision of ART reduces viral load—ultimately decreasing HIV transmission in the larger community.117

This national public health issue and the ongoing global HIV/AIDS pandemic are exacerbated by substance use, which serves as a powerful cofactor at every stage, including transmission, diagnosis, illness trajectories, and treatment. Since the beginning of the epidemic in the 1980s, drug use and HIV have been inextricably linked. Today, illicit drug use is an important driver of HIV across the globe.118 Intravenous drug use in particular continues to be a risk factor for transmission of the virus,118,119 accounting for approximately 6 percent of HIV diagnoses in 2015.120

In addition, drug use plays a more general role in the spread of HIV by increasing the likelihood of high-risk sex with infected partners.119 The intoxicating effects of many drugs can alter judgment and inhibition, and lead people to engage in impulsive and unsafe behaviors. Additionally, people who are addicted to drugs may engage in risky sexual behaviors to obtain drugs or money to buy them.119

Drug use and addiction can also hasten the progression of HIV and its consequences, especially in the brain. Clinical research indicates that drug use and addiction may increase viral load, accelerate disease progression, and worsen AIDS-related mortality even among patients who follow ART regimens.121 In addition, people with substance use disorders are less likely to take life-saving HIV medication regularly,107 which worsens the course of their illness.

Although it is unclear whether HIV infection contributes to drug use and addiction in human patients,121 animal studies suggest that both types of brain cells—neurons and glia—can be infected by HIV, causing neurobiological disruptions to brain circuits that are effected by drug use and addiction.122

Drugs can make it easier for HIV to enter the brain and trigger an immune response and the release of neurotoxins, which can cause chronic neuroinflammation.123 HIV-induced inflammation in the brain underlies the neurocognitive disorders, also called NeuroHIV, that are a complication of HIV infection.124 Around 50 percent of individuals with HIV and AIDS suffer from HIV-related neurocognitive disorders.125 NeuroHIV is challenging to diagnose and treat, since other factors—such as aging, drug use, addiction, and psychiatric illnesses—are common and can produce similar cognitive symptoms.126 There is an ongoing need for new therapeutic approaches to the neurological complications of HIV, as clinical trials of neuroprotective or anti-inflammatory medications have been unsuccessful.126

Because people with HIV are living longer due to effective treatments, the influence of the virus on the aging brain and neurocognition is a growing concern. Around half of all HIV-infected persons are 50 years old or over.127 Neuroimaging research conducted prior to effective treatment or on untreated individuals suggests that HIV accelerates aging of the brain. Comorbid substance use disorder may exacerbate neurological aging among people with HIV.127

Testing for and treating HIV in criminal justice settings benefits both the health of inmates and overall public health. People with HIV infection are overrepresented in prisons; in 2010, there were 20,093 inmates with HIV/AIDS in state and federal prisons.128 Most incarcerated individuals with HIV acquired it in the community prior to incarceration.129 Individuals with HIV often begin treatment while incarcerated, but they experience a disruption of care when they return to the community, in addition to facing challenges coping with substance use and mental health problems.130 Therefore it is particularly important to link people who have HIV and a history of substance use  to community HIV services, substance abuse treatment, mental health services, and other wrap around services in their community to reduce recidivism, improve their health, reduce the spread of the infection to others, and prevent relapse to substance abuse.129–131