Marijuana is a drug which is obtained from the cannabis plant and is often used in the form of cigarettes, or joints, by many people in the world. A recent research program by Northwestern Medicine revealed that young adults, who heavily abused marijuana for three consecutive years became poor at long-term memory and their hippocampus became distorted.

This study was published in the journal 'Hippocampus' on 12 March 2015. The study clearly states that the long-term memory which is the memory of life events is particularly affected by extensive usage of marijuana in teenagers. Furthermore, the abnormal shape of the hippocampus is significantly linked to the memory problem.

Researchers had previously reported the hippocampus distortion and poor long-term memory due to excessive usage of marijuana in separate studies. However, this is the first study which shows the link between these psychological and physiological abnormalities.

This report also disclosed that teenagers who smoked this drug performed 18% more poorly than a teenager who never smoked marijuana drug before. Moreover, the study also shows that marijuana abuse is directly proportional to the severity of an individual'shippocampus distortion. This means the longer the drug is abused, the more distorted the shape of the hippocampus. Other components of the hippocampus like its axons, neurons and its supportive environment may also get affected by the prolonged use of marijuana.

Another important finding of this research is that schizophrenic patients who smoked marijuana in their teens performed 26% worse than the schizophrenic patients who never smoked this drug.