Drop in IQ linked to heavy teenage cannabis use

NATURE NEWS ^ | 28 August 2012 | Leigh Phillips

[neverdem]

Starting to smoke pot in your teens can lead to cognitive decline not seen in those who start as adults.

Becoming a heavy cannabis smoker as a teenager results in cognitive decline not seen if the illicit drug use starts when adult.

Clinical psychologist Madeline Meier at Duke University in Durham, North Carolina, and her colleagues used data from the famous Dunedin Longitudinal Study, an ongoing multi-factor survey involving a cohort of 1,037 New Zealanders followed from birth, which now has 40 years worth of data. Participants in the Dunedin Study had been periodically tested for IQ and other neuropsychological indices as well as being asked about behaviour such as drug-taking. The study was published in the Proceedings of the National Academy of Sciences on Monday1.

When their adult IQ was tested at 38 years old, the heaviest and most persistent adolescent-onset users in the study had experienced an average decline of eight IQ points from childhood to adulthood. Non-users had on average increased their IQ by around one point. And even after setting aside the heaviest users, a decline of a few IQ points from their childhood value was still seen in less heavy users who had started in their teens. What's more, the drop in mental function seemed irreversible even after people had quit cannabis. However, persistent users who only started when adult (older than 18 years) did not seem to experience the same IQ...

--snip--

Valerie Curran, professor of psychopharmacology at University College London and a member of the UK's Independent Scientific Committee on Drugs, was more sceptical, saying that a other factors, such as depression, are also associated with heavy use and reduced motivation. “Although the overall sample size is excellent, the data on adolescent onset of heavy use is based on just over 50 people.”...

[neverdem]

Can it explain the choom gang?

[Doogle]

Doh!

[2ndDivisionVet]

[JewishRighter]

So this explains how Obama got elected and how he can still be competitive in this race! OHHHHHHHHHH.

[Berlin_Freeper]

Put teenagers in the army reserve.

[billorites]

cha?

[dfwgator]

Whut?

[detective]

Obama was a heavy user of cannabis and other drugs throughout his adolescence. It had to have had an effect on him.

[stephenjohnbanker]

It didn’t help

[opentalk]

There is also a Harvard study, fluoride lowers IQ,MSM ignores.

[donna]

Wow man, what?

[b4its2late]

Democrats for sure.

[WilliamofCarmichael]

Scientists explain the Obama Effect . . . .

[donna]

Double dumb!

[chaos_5]

Ummm... maybe thats why they call it “dope”...

[Hardraade]

Zero! With an IQ of Zero!

May also explain the notorious NZ antisemitism.

[KosmicKitty]

[Wuli]

the difference between “early onset teen heavy users” and later “adult onset” users, with regard to the IQ studies, is likely due to the fact that all the neurological pathways for critical analysis in the brain are not yet complete in our teens, and is therefore interfered with by the heavy cannabis use in teens

then again, maybe the choice of becoming a heavy cannabis user as a teen reflects a lower IQ to start with; I wonder if their data/research shows that or not

[andyk]

I wonder what heavy alcohol use does to teens.

[EEGator]

" Fluoridation is the most monstrously conceived and dangerous communist plot we have ever had to face."