Marijuana may have a strong effect on the brain because the main active ingredient, THC, is carried from the bloodstream to the brain and other organs. These reactions produce the immediate high of marijuana use, but may also have long lasting emotional effects when someone is addicted to the drug. Thoughts, memories, concentration and sensory perception are affected and can have an adverse impact on mental abilities.
Marijuana may cause an initial stimulation that brings a sense of euphoria followed by tranquility, according to the Center for Substance Abuse Research at the University of Maryland. The pleasant sensations may pass after a while and may lead to drowsiness. The opposite effect of depression may set in, but it may lead to addiction in an attempt to regain the pleasurable effects.
Because the brain is affected, there may be difficulty in thinking, problem solving, learning and memory. Time may seem to pass more slowly during use. Difficulty with memory may last for days. A person addicted to marijuana or who smokes it every day may lose some of his brain's intellectual functioning. It may be difficult to form memories or recall events. Long-term use may interfere with math and verbal skills or the capacity to store and retrieve information.
Anxiety, panic or paranoia may develop during marijuana intoxication. There may be intense feelings that cause the person to exaggerate thoughts. In some cases, a person may think of things that bring contentment. But other times the feelings may activate negative thoughts that the person has done something wrong or cause a distrust of people. Heavy marijuana use may exacerbate mental problems, such as anxiety and depression, or cause them. Marijuana may be used as a self-medication to relieve problems, but may have the opposite effect of intensifying them.
A person who uses marijuana regularly may start to lose interest in activities once enjoyed. Addiction to marijuana may cause someone to withdraw from social activities that involve the family, work, school or recreational functions. The loss of interest may be the result of the carelessness or recklessness that often accompany long-term marijuana use.
Negative effects may be experienced when stopping the use of marijuana, according to the Health Services at Columbia University. The emotional symptoms may include depressive moods, anger and aggression, restlessness, irritability and strange dreams. The behavioral symptoms may not be as strong as those experienced from other drug use. As with withdrawal from other drugs, the emotional attachment to marijuana may threaten to bring a user back to the drug.