Hemp studies cast doubt on the theory that smoking kills the IQ

New findings: makes smoking really stupid?
The consumption of marijuana makes stupid, the brain shrinks by kiffen: This has been suggested by research in recent years. Other studies - even a very recent - hold against it. The intelligence thus suffers from something else that presumably seduces also to Kiffen.
Proponents and opponents
The question of whether to release hemp or not, has been fierce for years. Conservatives are concerned, among other things, with the fact that consumption could lead to other drugs. More advanced people like to highlight the health benefits of marijuana. Its effectiveness is scientifically proven, among other things, for nausea and vomiting. And recently, a study confirmed that cannabis is helpful against migraine. Another point the critic often cites is that consuming marijuana should make teenagers stupid. However, scientists have long argued about this thesis. A recent investigation now holds against. The intelligence thus suffers from something else - and probably seduces also to Kiffen.

New investigation raises doubts about existing thesis. Picture: juniart - fotolia

Doubts about a longer existing thesis
In adolescents, the brain is still in its identification phase. Therefore, many assume that you endanger your intelligence, if you already kifft in these young years. As Spiegel Online reports, a new analysis is now fueling doubts about this thesis. According to researchers from Loyola Maymouth University in Los Angeles, smoking marijuana is just a symptom of the factor that also causes intelligence to wane. However, the intelligence loss has nothing to do with drug use directly.

Various factors influence the intelligence
Previous studies that linked IQ to high cannabis use in adolescence had a fundamental weakness: the analyzes were based on observations in real life. However, one can not differentiate whether it is the Kiffen, which acts on the intelligence. Rather, other factors such as the environment or genes could play an important role. Twin studies reduce the risk of such bias. The scientists from the USA took advantage of this. Her current analysis is based on two twin studies with a total of more than 3,000 participants. As the researchers in the journal "PNAS" report, all study participants had completed a number of intelligence tests at the age of nine to twelve for the first time. None of them had used cannabis at this time. At the age of 17 to 20, the tests were repeated.

No differences between stingers and abstainers
These data were used to analyze which subjects had deteriorated over time and if there was a link with their cannabis use. Most of the tests showed no difference between stingers and abstainers. Only with exercises to the vocabulary and general knowledge the marijuana smokers performed worse. Another finding: Between people who consumed little cannabis and those who smoked a lot, they found only minimal differences.

Investigations with twin pairs
In a further step, the researchers focused on the twin pairs, where one stoned and the other did not. These people are particularly well suited for a comparison, since they mostly grew up in the same environment. 137 of these 290 twin couples were according to the information even one. Again, it was found that there were hardly any differences between the siblings. Joshua Isen, a psychologist at Loyola Maymouth University, Los Angeles, concludes from the findings that a high-risk teenage boy is likely to experience an IQ decline regardless of whether he actually starts consuming it. It is unclear, however, what links the two factors together. In addition, it should be noted that the work says nothing about other harmful consequences of teenage killing. (Ad)