The use of marijuana is most often associated with diminished motor skills, slowed reaction time, an...

1. Marijuana Alters Brain and Impairs Long Term Memory
The use of marijuana is most often associated with diminished motor skills, slowed reaction time,
and increased appetite. The marijuana movement sweeping across America has led to an increased
interest in research on the drug. At Northwestern Medicine, a new study has found that teenage
marijuana use, smoking the drug on daily basis for about three years, effects long-term memory,
ScienceDaily reports.
Long-term users were found to have abnormally shaped hippocampus', which is known to play an
important role with long-term memory (episodic memory), the ability to remember autobiographical
or life events. Participants in the study, now in their early twenties and had stopped using for two
years, were found to have performed about 18 percent worse on long-term memory tests, compared
to those who had never abused the drug, according to the article.
"The memory processes that appear to be affected by cannabis are ones that we use every day to
solve common problems and to sustain our relationships with friends and family," said senior author
Dr. John Csernansky, the Lizzie Gilman professor and chair of psychiatry and behavioral sciences at
Northwestern University Feinberg School of Medicine and Northwestern Memorial Hospital.
The Northwestern Medicine study is one of the first to show abnormalities of the hippocampus due
to heavy marijuana use, the article reports.
"Both our recent studies link the chronic use of marijuana during adolescence to these differences in
the shape of brain regions that are critical to memory and that appear to last for at least a few years
after people stop using it," said lead study author Matthew Smith, assistant professor of psychiatry
and behavioral sciences at the Feinberg School of Medicine.
Smith points out that a longitudinal study is required to determine if marijuana is responsible for the
observed differences found in the brain and the loss of memory.
"It is possible that the abnormal brain structures reveal a pre-existing vulnerability to marijuana
abuse," Smith said. "But evidence that the longer the participants were abusing marijuana, the
greater the differences in hippocampus shape suggests marijuana may be the cause."
The findings were published in the journal Hippocampus.