Does Weed Make You Stupid?

One of the primary short term effects of tetrahydrocannabinol (THC) on the brain is a disruption of memory functionality. The principal region within the brain responsible for memory function is called the hippocampus. When cannabinoid receptors are activated in the hippocampus they interfere with and potentially disrupt a cellular process called, long-term potentiation. This cross signalization between neurons is largely responsible for the formation of new memories. Motor coordination, judgement and reaction time are also negatively affected by absorption of THC. The largest concentration of cannabinoid receptors are located in two area of the brain; the striatum and substantia nigra, respectively. These two nerve centers facilitate the coordination of movement and are effected negatively when exposed to THC – they are also among the first to deteriorate within the central nervous system in individuals suffering from Parkinson’s Disease (a neurological disorder that severely hinders motor function). Per one study in the journal of Pharmacology, Biochemistry and Behavior in 2002, utilizing PET (positron emission tomography) scans, activity within the brain was measured and revealed that frequent users, as compared to non-users, had decreased activity in the cerebellum–an area in the brain linked with coordination and balance.

Acute cannabis intoxication has been shown to affect consistency in attention, psychomotor task ability, and short-term memory; however, a dose-response relationship has not been formally established as of yet. Considering the effect on both the motor control portion of the central nervous system and difficulty in formation of new memories, marijuana usage is academically suspected to hinder the ability to form new motor skills. Acute intoxication effects are often misrepresented as long term cognitive effects. Data has effectively demonstrated, however, that chronic exposure to cannabis/THC needs longer to “flush out” of the users’ system and thus the acute intoxication effects appear to persist. Adequate time for wearing off produces data that corroborates no difference in the implementation of cognitive tasks.

In the short-term, post usage and during usage, cannabis has a negative impact on several neurological functions. Given time, however, cognitive ability of the user returns to normal (prior to absorption of THC).