cohort
大麻を習慣的に吸引すると、IQの低下につながり、社会的にも栄達はのぞめないという科学的な調査が発表されました。１０００人の協力者を得て、２０年にもわたるNZのダニーデンでの大がかりな調査には説得力があります。
cohortは「歩兵、軍隊」、また「相棒、仲間」という意味で用いられますが、統計学（Stats）では「被験者の一団」という意味でも用いられます。（GP）
Young cannabis smokers run risk of lower IQ, report claims
By Dominic Hughes
Health correspondent, BBC News
Young people who smoke cannabis run the risk of a significant and irreversible reduction in their IQ, research suggests. The findings come from a study of around 1,000 people in New Zealand.
An international team found those who started using cannabis below the age of 18 - while their brains were still developing - suffered a drop in IQ. A UK expert said the research might explain why people who use the drug often seem to under-achieve.
For more than 20 years researchers have followed the lives of a group of people from Dunedin in New Zealand. They assessed them as children - before any of them had started using cannabis - and then re-interviewed them repeatedly, up to the age of 38.
Having taken into account other factors such as alcohol or tobacco dependency or other drug use, as well the number of years spent in education, they found that those who persistently used cannabis suffered a decline in their IQ.
The more that people smoked, the greater the loss in IQ.
中略
Robin Murray, professor of psychiatric research, also at the King's College London Institute of Psychiatry but not involved in the study, said this was an impressive piece of research.
"The Dunedin sample is probably the most intensively studied cohort in the world and therefore the data are very good. "Although one should never be convinced by a single study, I take the findings very seriously.
