Pubdate: Wed, 05 Sep 2012
Source: Nigerian Tribune (Nigeria)
Copyright: 2012 African Newspapers of Nigeria Plc.
Author: Sade Oguntola


Both the dangers of smoking cannabis and its potential health 
benefits have been a source of controversy for many years. The latest 
study on the drug suggested that heavy and prolonged cannabis smoking 
as a young person can result in a permanently lower IQ, reports Sade Oguntola.

Persistent use of marijuana when the brain is undergoing critical 
development may have toxic effects on brain cells. Of particular 
worry is the permanence of these effects among people who began 
smoking marijuana in adolescence. Even after these subjects stopped 
using marijuana for a year, its adverse effects persisted.

The United Nations says that marijuana is the most popular illegal 
drug in the world, with somewhere between 119 million and 224 million 
users between the ages of 15 and 64 as of 2010. Within the United 
States, for instance, 23 per cent of high school students said they'd 
recently smoked marijuana, making it more popular than cigarettes.

The idea that marijuana harms the adolescent brain has warranted 
scientists investigating its impart on memory. Prior to now, concerns 
regarding cannabis use were ideological rather than legal. 
Interestingly, a new study that gives credence to the long term 
effect of marijuana on the brain cells found that its use in young 
people affects their mental performance. It blunts intelligence, 
attention and memory, aside reducing their IQ.

The IQ - or intelligence quotient - does not measure a person's 
amount of knowledge, but rather represents a person's ability to 
comprehend concepts, as well their capacity to process information. 
Typically, IQ does not change significantly over the course of a 
person's life, unless as a result of severe brain damage from injury 
or disease. But intelligence and cognition are affected by a plethora 
of other factors, including genetic, social and environmental 
influences that may supersede any influence from drug use.

In a study of more than 1,000 adolescents in New Zealand, those who 
began habitually smoking marijuana before age 18 showed an 
eight-point drop in IQ between the ages of 13 and 38, a considerable 
decline. The average IQ is 100 points. A drop of eight points 
represents a fall from the 50th percentile to the 29th percentile in 
terms of intelligence.

In the research, published in the Proceedings of the National Academy 
of Sciences, which charted the IQ changes in participants over two 
decades, researchers tested the IQs of all of the study subjects at 
age 13 before any habitual marijuana use. They then split the study 
into five "waves" during which time they assessed cannabis use - ages 
18, 21, 26, 32, and 38. They again tested IQ at age 38. Besides 
factors that could affect mental performance such as years of 
education, alcohol use and other psychoactive drugs that may affect 
IQ were taken into consideration.

The researchers also had family members and friends of the 
participants confidentially rate them on attention and memory skills 
and those who had lost IQ points showed problems in these areas.

The eight-point drop in IQ was found in subjects who started smoking 
in adolescence and persisted in "habitual smoking". These were young 
people that use cannabis at least four days per week. However, in 
people who started smoking in adolescence but used marijuana less 
persistently, the researchers in the Proceedings of the National 
Academy of Sciences found that the effect on their IQ's was less 
pronounced than the group that used it early and persistently. In 
contrast, those who never used marijuana at all gained nearly one IQ 
point on average.

Experts in child development said the reasons young people may be 
more susceptible to the harmful effects of marijuana may have to do 
with a substance called myelin. Myelin can be thought of as a kind of 
insulation for nerve cells in the brain that also helps speed brain 
signals along - and in adolescent brains, the protective coating it 
forms is not yet complete.

But how could cannabis have this effect on the brain and why might 
teenagers be particularly susceptible? The drug is made from the 
cannabis plant and contains more than 400 different chemicals, which 
could have a range of effects on the mind and body. It includes 
psychoactive chemicals which act on the brain. The main element is a 
chemical called tetrahydrocannabinol (THC). This provides the 
"chilled out" sensation associated with smoking cannabis, but has 
also been linked to memory impairment.

Meanwhile, although the study was conducted among New Zealand young 
people, the findings could be extended to adolescents in many parts 
of the world, Nigeria inclusive. Many teenagers today are more likely 
to be using marijuana than tobacco products. According to 2011 World 
Drug Report annual prevalence of the youth and adult population who 
had consumed marijuana, at least once in the past was 14.3 per cent.

Unfortunately, 2011 was the first year in which adolescents smoked 
more marijuana than cigarettes. Many young people were wrongly 
influenced to believe that cigarettes are dangerous and that 
marijuana is not. Besides, factors such as child abuse or other 
trauma might lead people to seek escape in heavy marijuana use.

Even though more information is needed to establish the exact effects 
of marijuana on the developing mind, experts said that it was 
important for adults and teenagers alike to have a better 
understanding of just what marijuana does to their minds and bodies. 
Though the long-term effects of cannabis have been studied, there 
remains much to be concluded. Many studies have investigated whether 
long-term use of cannabis can cause or contribute to the development 
of illnesses such as heart disease, bi-polar disorder, depression, 
mood swings or schizophrenia.

Both advocates and opponents of the drug are able to call upon 
numerous scientific studies supporting their respective positions. 
For instance, while cannabis has been implicated in the development 
of various mental disorders in some studies, these studies differ 
widely as to whether cannabis use is the cause of the mental problems 
displayed in heavy users, whether the mental problems are exacerbated 
by cannabis use, or whether both the cannabis use and the mental 
problems are the effects of some other cause.

Tests have implied that smoking of marijuana could impact the sperm's 
functions, though this impact is unknown. There is some evidence that 
cannabis may compromise female fertility with a modest association 
reported between cannabis use and infertility in a case controlled 
study of 150 women with primary infertility.

Higher rates of testicular cancer in western nations have been linked 
to use of cannabis. A 2009 study published in the journal Cancer 
linked the long-term use of cannabis to an increased risk of 70 per 
cent for testicular cancer with the scientists concluding that 
cannabis is harmful to the human endocrine and reproductive system.

Some studies have found that children of tobacco and 
marijuana-smoking mothers more frequently suffer from permanent 
cognitive deficits, concentration disorders, hyperactivity, and 
impaired social interactions than non-exposed children of the same 
age and social background.
- ---
MAP posted-by: Jay Bergstrom