Marijuana and Mental Health

Marijuana use is linked to an increased risk of psychiatric problems, including anxiety, depression, schizophrenia and post-traumatic stress disorder. Research indicates that marijuana can speed the onset of schizophrenia and worsen its trajectory in those predisposed to the disease.

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Marijuana use appears to have skyrocketed in recent years. A 2017 poll by Yahoo News and Marist College estimated that nearly 55 million adults in America currently use marijuana — more than double the number reported by the federal government in 2015.

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Even as it’s gone mainstream, marijuana poses an increased risk for psychiatric disorders, including anxiety, depression, addiction and psychosis.

A 2017 study in The American Journal of Psychiatry found that nearly half of 6,788 patients who experienced marijuana-induced psychosis went on to develop schizophrenia or bipolar disorder.

And despite the fact that many people use marijuana to treat symptoms of post-traumatic stress disorder, research has shown that weed can worsen the condition.

How Marijuana Affects the Brain

Marijuana is a psychoactive substance, meaning it changes the way a person thinks and feels. THC, the main psychoactive ingredient in marijuana, generates many of the drug’s mind-altering effects.

When someone smokes, vapes or ingests pot, THC latches to cannabinoid receptors in the brain that affect pleasure, thought, concentration, sensory and time perception, memory and coordinated movement.

Most people who use pot recreationally seek the happy and relaxed, or “stoned,” feeling that the drug provides. But weed has undesirable effects as well. It can impair thinking and the ability to form new memories. The drug can also make it difficult to concentrate and perform complex tasks.

In some people, marijuana can trigger anxiety, panic, paranoia and confusion. High doses of pot can even cause temporary psychotic symptoms, such as hearing voices and experiencing unwarranted feelings of paranoia or persecution.

Chronic marijuana use has been linked to other mental health problems, including depression, anxiety and bipolar disorder. The drug can also worsen schizophrenia and lead to marijuana addiction. People addicted to marijuana will compulsively seek and use the drug despite its negative effects on their life.

Marijuana and Anxiety

For many people, marijuana has a calming or sedating effect. But in some, it can trigger paranoia, anxiety and panic attacks.

Anxiety is more common with higher doses of the drug, but it can even occur with infrequent pot use.

The links between marijuana and anxiety aren’t entirely understood. While studies have shown that chronic marijuana use in adolescence is associated a greater risk of anxiety disorders later in life, it’s unclear if marijuana actually causes persistent anxiety disorders.

Some research suggests that people with anxiety may use marijuana as a form of self-medication — and that other genetic or environmental factors, such as childhood trauma and poverty, can contribute to anxiety and marijuana use.

Depression and Mood Disorders

The link between marijuana and depression isn’t entirely understood either.

While proponents of medical marijuana claim that weed can help alleviate depression, some studies have shown an increased risk of depression with marijuana use.

An Australian study out of the Centre for Adolescent Health, Murdoch Children’s Research Institute found that teens who smoked pot weekly were twice as likely to develop depression later in life. Young women who used marijuana daily were more than five times as likely as nonusers to report a state of depression and anxiety.

It is still unclear whether marijuana causes depression or whether individuals with depression may gravitate toward using marijuana.

Marijuana use in common among individuals with bipolar disorder, also known as manic-depressive illness, and it tends to complicate treatment of the disease.

Bipolar disorder causes alternating episodes of depression and mania. During depressive episodes, people may feel sad, hopeless, tired and have suicidal thoughts. In the manic phase of the illness, they may experience increased energy levels, racing thoughts, insomnia and, in severe cases, psychosis.

A 2017 study in the journal Schizophrenia Bulletin found that teens who use weed several times a week are more likely to develop a mild form of mania. The researchers reported that early marijuana use may lead to bipolar disorder later in life.

As with depression, the connections between marijuana use and bipolar disorder are not entirely clear.

Marijuana and Schizophrenia

Schizophrenia is a complex and often disabling brain disease that causes hallucinations, distorted thinking and emotional problems. The symptoms of schizophrenia usually show up between the ages of 16 and 30. The mental illness rarely occurs after the age of 45.

While weed can trigger acute psychotic symptoms in people who don’t have the mental health condition, scientists have uncovered links between marijuana and schizophrenia.

Marijuana use doesn’t appear to cause schizophrenia, but it can trigger the disorder early in people with genes that make them more vulnerable to the condition.

Heavy marijuana use can accelerate a person’s first psychotic episode by two to six years, according to a 2014 study in the Schizophrenia Bulletin. Long-term use of weed may also worsen symptoms of the illness.

Marijuana and Post-Traumatic Stress Disorder

Post-traumatic stress disorder, also called PTSD, is an anxiety disorder that can develop after a traumatic or life-threatening event. War combat, sexual assault, natural disasters and other traumatic events can all trigger PTSD.

While some people, including military veterans, use marijuana to relieve their PTSD symptoms, research has not confirmed the safety or effectiveness of using the drug as a PTSD treatment.

Marijuana may provide short-term relief from PTSD, but in the long run it can make the disorder worse. A 2015 study in The Journal of Clinical Psychiatry found that long-term use of marijuana by war veterans with PTSD was associated with an increase in PTSD symptoms, violent behavior and alcohol use.

Symptoms of PTSD can include:

  • Having vivid recurrent memories (flashbacks) or nightmares of the traumatic event
  • Experiencing negative feelings such as guilt, shame or extreme distrust of others
  • Avoiding people and situations that trigger traumatic memories
  • Feeling nervous or jittery
  • Having difficulty sleeping
  • Experiencing emotional instability, including sudden bursts of anger and irritability

Researchers studying marijuana and PTSD have found a biological basis for why marijuana temporarily alleviates the symptoms of PTSD. A 2013 study found that people with the disorder have more cannabinoid receptors in parts of their brain associated with fear and anxiety than individuals without PTSD.

Marijuana and Substance Use Disorders

While people often think of marijuana as a benign drug, weed is addictive. Nearly a third of people who use weed may have some degree of a marijuana use disorder, which can range from a mild substance abuse problem to addiction.

Some studies estimate that 9 percent of people using the drug develop a physical dependence to it. People who are dependent on marijuana need it to feel normal and experience withdrawal symptoms when they stop using the drug.

Early use of marijuana is even more likely to cause problems. According to the National Institute on Drug Abuse, kids and teens who smoke pot before the age of 18 are four to seven times more likely to develop a problem with marijuana, and about 17 percent will develop a dependence on the drug.

Early marijuana use can prime the reward centers of the brain for substance abuse problems later in life. This is one reason marijuana is sometimes considered a gateway drug.

While many states have legalized marijuana, the U.S. government classifies the drug as an illegal Schedule I substance with no accepted medical use and a high potential for abuse.

Medical Disclaimer: aims to improve the quality of life for people struggling with a substance use or mental health disorder with fact-based content about the nature of behavioral health conditions, treatment options and their related outcomes. We publish material that is researched, cited, edited and reviewed by licensed medical professionals. The information we provide is not intended to be a substitute for professional medical advice, diagnosis or treatment. It should not be used in place of the advice of your physician or other qualified healthcare provider.

Amy Keller, RN, BSN
Content Writer,
As a former journalist and a registered nurse, Amy draws on her clinical experience, compassion and storytelling skills to provide insight into the disease of addiction and treatment options. Amy has completed the American Psychiatric Nurses Association’s course on Effective Treatments for Opioid Use Disorder and continuing education on Screening, Brief Intervention and Referral to Treatment (SBIRT). Amy is an advocate for patient- and family-centered care. She previously participated in Moffitt Cancer Center’s patient and family advisory program and was a speaker at the Institute of Patient-and Family-Centered Care’s 2015 national conference.

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