A study led by psychiatrist Igor Grant was conducted on 700 regular marijuana users and 484 non-users. Various aspects of the brain were tested, such as reaction time, language, memory, motor skills, and reasoning. The marijuana users in this study smoked marijuana daily, weekly, or monthly yet researchers concluded that impairments were less than those found from using alcohol or other drugs. The researchers concluded that brain damage was not directly affected by marijuana use; however the outcomes may have been different if these tests were conducted on a child whose nervous system is still in development.
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