A new study has shown that people who smoke marijuana as young adults risk a slightly harder time recollecting words by the time they reach middle age.
The same study, according to CBS, says put use does not appear to cause any damage or dim other mental capacities, such as the ability to think fast, concentrate or problem-solve.
“We were really surprised by the findings,” said study author Dr. Reto Auer, an academic chief resident in the department of community medicine and ambulatory care at the University of Lausanne, in Switzerland.
The impact of Pot on the ability to memorize words appeared to be incremental, meaning that “the more you smoke, the lower your verbal memory,” Auer was quoted to have said by the CBS.
Still, Auer stressed that the results “are only associations,” and not proof of cause and effect. He also said the study only examined the impact of pot on verbal memory, not overall memory, and didn’t assess whether participants or their friends thought pot smoking had actually left them impaired.
Auer and his team of researchers reported their findings in the Feb. 1 online edition of JAMA Internal Medicine.
In order to explore the potential long-term impact of marijuana use, the researchers focused their attention on nearly 3,400 white and black men and women who were between the ages of 18 and 30 when they first enrolled in a national study in 1985 and 1986 respectively.
Those who took part in the research were residents of Birmingham, Ala.; Chicago; California; Oakland and Minneapolis. All participants were tracked for the next 25 years (up until 2011), during which time use of marijuana was self-reported at seven follow-up interviews.
According to the study, 85 percent of participants admitted to smoking pot at some point of another, while about 12 percent said they continued to do so in middle age.
Thinking skills were assessed at the end of the 25-year study period. The testing covered verbal memory, measured by the ability to memorize and recall a list of 15 words, including; visual motor speed; working memory; sustained attention skills; and the ability to problem-solve and plan.
At the end of the study, the researchers were able to determine that middle-aged participants who were smokers of marijuana when they reached the 25-year mark fared worse in terms of verbal memory and mental-processing speed.
Also discovered during the study was that the greater an individual’s lifelong exposure to pot, the more their verbal memory seemed to have dimmed by middle age.
The result of this research means that those who smoke marijuana every day for many years are the most likely to experience the greatest drop in thinking skills, according to Wayne Hall, the author of an accompanying editorial.
“The study did not measure use precisely, but the pattern of cannabis use that most often produces these type of effects is daily use over a decade or more,” Hall said.
“Cannabis is a drug, and like all drugs it can harm some users when they use it in particular ways. This study adds to the substantial evidence that the daily use of cannabis over periods of years and decades can harm the mental and physical health of people who use it in this way,” he added.