[This is the first part of a series that explores the relationship between mental illnesses and substance abuse a means of self-medicating the illness.}

As a means of raising public awareness of mental illness in the United States, several research organizations have assembled statistics, including the National Institute of Mental Health (NIH).

According to NIH, more than one in five U.S. adults were estimated to live with a mental illness in 2021.

In 2021, there were an estimated 57.8 million adults aged 18 or older in the United States with any mental illness (AMI). This number represented 22.8% of all U.S. adults.

• The prevalence of AMI was higher among females (27.2%) than males (18.1%).

• Young adults aged 18-25 years had the highest prevalence of AMI (33.7%) compared to adults aged 26-49 years (28.1%) and aged 50 and older (15.0%).

• The prevalence of AMI was highest among the adults reporting two or more races (34.9%), followed by American Indian / Alaskan Native (AI/AN) adults (26.6%). The prevalence of AMI was lowest among Asian adults (16.4%).

As the National Alliance for Mental Illness (NAMI), states:

“It’s important to measure how common mental illness is, so we can understand its physical, social and financial impact — and so we can show that no one is alone. These numbers are also powerful tools for raising public awareness, stigma-busting and advocating for better health care.”

To fulfill its goal of raising awareness and reducing stigma, NAMI gathered statistics from the 2021 national survey on drug use and health conducted by the Substance Use and Mental Health Services Administration (SAMHSA). Those are:

• 22.8% of U.S. adults experienced mental illness in 2021 (57.8 million people). This represents 1 in 5 adults.

• 5.5% of U.S. adults experienced serious mental illness in 2021 (14.1 million people). This represents 1 in 20 adults.

• 16.5% of U.S. youth aged 6-17 experienced a mental health disorder in 2016 (7.7 million people)

• 7.6% of U.S. adults experienced a co-occurring substance use disorder and mental illness in 2021 (19.4 million people)

SAMHSA divides mental illness into two categories: Any Mental Illness (AMI) and Serious Mental Illness (SMI).

Any mental illness (AMI) is defined as a mental, behavioral, or emotional disorder. AMI can vary in impact, ranging from no impairment to mild, moderate, and even severe impairment (e.g., individuals with serious mental illness as defined below).

Serious mental illness (SMI) is defined as a mental, behavioral, or emotional disorder resulting in serious functional impairment, which substantially interferes with or limits one or more major life activities. The burden of mental illnesses is particularly concentrated among those who experience disability due to SMI.

SAMHSA in April, 2023 reported that mental health problems and substance use disorders sometimes occur together. Reasons include:

• Certain substances can cause people with an addiction to experience one or more symptoms of a mental health problem

• Mental health problems can sometimes lead to alcohol or drug use, as some people with a mental health problem may misuse these substances as a form of self-medication

• Mental health and substance use disorders share some underlying causes, including changes in brain composition, genetic vulnerabilities, and early exposure to stress or trauma.

The report revealed that more than one in four adults living with serious mental health problems also has a substance use problem. Substance use problems occur more frequently with certain mental health problems, including depression, anxiety disorders, Schizophrenia, and Personality Disorder. There is a reason for the correlation between substance abuse, addiction, and mental health conditions, which is often referred to as self-medication.

A Science Direct scholarly article titled Revisiting the self-medication hypothesis from a behavioral perspective, published in 2000, states:

“The self-medication hypothesis (SMH) suggests that clients use substances as a means to reduce their psychiatric symptoms.”

However, substance use as a form of self-medication also can be interpreted as exacerbating symptoms, the authors wrote. Behavioral principles may provide a useful perspective to understand this apparent contradiction.

E.J. Khantzian, MD, writing for Psychiatric Times, wrote in 2017 that the SMH maintains that suffering, and not pleasure seeking, is at the heart of addictive disorders, such that addictive drugs have appeal, because during the short term they relieve painful feelings and psychological distress.

There is a considerable degree of preference in a person’s drug of choice, Khantzian says.

“But it isn’t as though a person ‘chooses’ a drug; rather, while experimenting with various drugs he or she discovers that the effect of a particular drug is experienced as welcome because it changes or relieves especially painful or unwanted reasons special to that person.”

Yet, Khantzian cautions, the SMH theory has also been trivialized and dismissed. The expression “self-medication” has become a household expression that detracts from the emotional suffering and complexities of feelings that are at the root of a person’s need to self-medicate.