Dual Diagnosis
The co-occurrence of marijuana use disorder and mental illness is commonly referred to as a dual diagnosis. Marijuana use is prevalent and has the potential for causing both physical and psychological dependence. In 2013, approximately 20 million people over the age of 12 used marijuana in the U.S. Thus, many individuals with a mental health disorder might also be using marijuana.
Marijuana and the Brain
Marijuana acts primarily on cannabinoid receptors in the brain. We naturally produce substances that bind to these receptors, called endocannabinoids. Marijuana contains a chemical called tetrahydrocannabinol (THC) which exogenously (i.e., from the "outside") binds with cannabinoid receptors. This leads to the psychological experience of being "high," along with the drug's action on other mood-regulating neurotransmitters, like dopamine.
Those who are sensitive to higher levels of the neurotransmitter dopamine, or already have higher levels, can experience: Aggression; Physical agitation; Anxiety; Panic. They could also experience some types of depression, mania, delusions, hallucinations and/or paranoia.
Brain Structure
The brain changes caused by intoxication are often mistakenly thought to be only temporary and only chemical in nature. Research indicates, however, that marijuana use also negatively alters brain structure. For example, marijuana used once per week has been associated with altered size and shape of brain structures, specifically, the nucleus accumbens and amygdala; responsible for regulating motivation and emotion. Another brain structure important in learning and memory--the hippocampus--also appears to be vulnerable to structural alterations as a result of marijuana use. It is not known if any of these effects upon brain structure can be reversed.
Marijuana's stimulation of dopamine release in the brain can increase these already troublesome symptoms or cause the dormant vulnerability to them to awaken. If you are suffering from an addiction to marijuana, you may have developed mental health problems that require treatment.
Mood Disorders
There are strong links between mood disorders (such as Depression or Bipolar Disorder) and marijuana use. Research shows that marijuana use may increase depressive symptoms in users; however, it is unclear to what degree social and contextual factors play a role.
Read more at:https://www.mentalhelp.net/articles/marijuana-addiction-mental-health-problems/
Aspirin, Aleve, Advil, Tylenol can affect you that way too. Marijuana is a bit stronger in helping you deal with your pain.