As marijuana becomes more accessible to young and old alike in the U.S., researchers warn that long-term use of the drug may cause lasting harm to at least one type of brain function.

A new study based on following thousands of young adults into middle age finds that long-term marijuana use is linked to poorer performance on verbal memory tests, but other areas of brain function do not appear to be affected.

“We did not expect to find such a consistent association with verbal memory for chronic exposure to marijuana,” especially since the link held even when other factors like cigarette smoking, alcohol use and other behavioral factors associated with marijuana use were accounted for, said lead author Dr. Reto Auer of the University of Lausanne, Switzerland.

Auer and colleagues analyzed data from a 25-year U.S. study of young adults, which included repeated measures of marijuana exposure over time and a standardized test of verbal memory, processing speed and executive function in year 25. Almost 3,500 participants completed the standardized tests.

At the beginning of the study period in the 1980s, participants were 18 to 30 years old and more than 80 percent reported past marijuana use. Just 12 percent continued to use marijuana into middle age, according to the results in JAMA Internal Medicine.

Researchers found that as past years of marijuana use increased, verbal memory scores decreased. In practical terms, the results meant that for every additional five years of exposure, 50 percent of marijuana users would remember one less word from a list of 15 tested words.

“Recreational marijuana users use it to get high, to benefit from the transient change it produces,” Auer told Reuters Health by email. “But this transient effect might have long term consequences on the way the brain processes information and could also have direct toxic effects on neurons.”

But, he said, it is unclear from this observational study if lower verbal memory is a cause or a consequence of marijuana use.

The study only included self-reported marijuana use and did not employ brain imaging to measure structural changes, the authors note.

“Unfortunately, as with all recreational drug exposures, it would not be feasible to perform a long term randomized controlled trial to verify causation,” Auer said. “We are left with trying to do the best we can in epidemiological studies and adjust for potential confounders to estimate the potential causal effect of marijuana on health outcomes.”

Several studies have found that cannabis users who have used daily over years, and especially those who have used daily for decades, perform worse on various cognitive tasks than their peers who have either not used cannabis or have used it less frequently, for shorter periods, then stopped, said Wayne Hall, of the University of Queensland, Australia, who coauthored a related commentary.

“People who used occasionally in their 20s and discontinue as most cannabis users do, are at low risk of developing any cognitive impairment,” Hall told Reuters Health by email.

“But cannabis is a drug, and like all drugs, it can harm users when used in particular ways,” Hall said. “This message needs to be communicated to all cannabis users and especially those in U.S. states where medical or recreational cannabis use by adults is now legal.”

The new results did not include information on how the marijuana was consumed, only on the number of days of exposure in the month before each exam, Auer said.

All marijuana users and the overall population interested in knowing the health consequences of marijuana should have access to balanced, high quality information from independent researchers, but no study has repeatedly measured brain structure and marijuana use over time, Auer said.

“There is a severe lack of well performed studies on the topic, especially considering the proportion of the population who have been exposed, or are exposed to marijuana,” he said.

source: Reuters Health
http://www.reuters.com/article/us-health-cannabis-verbal-memory-idUSKCN0VA3BO

INVITATION FOR NOMINATION

Keio University Medical Science Fund is now accepting nominations for the Keio Medical Science Prize 2015. Established in 1996, Keio University annually awards the Keio Medical Science Prize to recognize researchers who have made an outstanding contribution to the field of medicine or life sciences.

Keio Medical Science Prize 2015

Criteria

·         Nominee must have a breakthrough in the fields of medicine and life sciences, and/or related fields.

·         Nominee must have an outstanding contribution to basic and clinical medicine.

Selection

            13 selection committee members and over 60 specialists from various fields, within and outside Keio University, will select laureates through rigorous review process.

Eligibility

            Nominees must be currently active in their field of research, and be expected to make future contributions to the field.

Prize

            Each laureate receives a certificate of merit, medal and a monetary award of 10 million yen.

Nomination

·         Individuals are limited to one nomination each.

·         Institutions or organizations may make as many nomination as they can.

·         In case of multiple nominations, nominations are limited to One nominee per research theme.

Note: A nomination should be for one researcher. Keio University does not accept nominations for groups.

Nomination Materials

·         Nomination form (*can be downloaded from http://www.ms-fund.keio.ac.jp/prize/)

·         Nominee’s curriculum vitae

·         Nominee’s bibliography

·         Copy of major publications (maximum of 5, each major publication must be a separate PDF file.)

Please send all materials listed above in separate PDF format files via email to

This email address is being protected from spambots. You need JavaScript enabled to view it., or by post to:

Office of the Keio University Medical Science Fund

                  35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan

Online nomination is also available at http://www.ms-fund.keio.ac.jp/prize/index.html

Deadline

      Nominations for 2015 must reach the Office of the Keio University Medical Science Fund by March 10, 2015.

For more information, visit http://www.ms-fund.keio.ac.jp/prize/index.html

Laoag City, Ilocos Norte - Among 18 entries for the research poster exhibit Saint Mary's University of Bayombong, Nueva Vizcaya bagged 1st place during the 1st Biennial Health Research Symposium held at Fort Ilocandia Resort Hotel, Laoag City, Ilocos Norte on June 26-27, 2014.

The study entitled "Antioxidant Screening of Selected Macrofungi from Mt. Palali, Nueva Vizcaya, Philippines" led by Marlon Saludarez & his teammates grabbed the attention of the judges due to its unique presentation & understandability of the research poster.

Second place went to Cagayan State University, through Prof. Andy Catulin of Carig campus. The board of judges expressed appreciation on the study entitled "Antibacterial Assay of Selected Microalgae Ethanolic Extracts Against Fish Pathogens" of CSU.

Third place went to Jocris Cabagun & teammates with Prof. Ramelo Ramirez with the study "Hepatoprotective Effect of Watermelon (Citrillus Vulgaris) on CC14-Induced Hepatic Injury in Albino Rats."

Certificates & cash prizes were awarded to the winners. For the first prize - P4,000.00, 2nd prize - P3,000.00, 3rd prize - P2,000.00 respectively.

On the whole, the success of the activity is attributed to the support of the Department of Science & Technology Regional Office 02 & the Cagayan Valley Health Research & Development Consortium.