Alf took special interest in the news item about cannabis and intelligence. Or lack of it.
The account at Stuff (here) says new research has found people who start using marijuana before the age of 18 and keep using it for years can cause lasting harm to their intelligence.
But those who did not start using pot until they were adults did not show similar mental declines.
The discovery was made by a team of researchers from this country, Britain and the United States, analysing data from more than 1000 people enrolled in the Dunedin Multidisciplinary Health and Development Study, which followed around 1000 people born in Dunedin in 1972 and 1973 from birth to age 38.
The research was published today in the Proceedings of the National Academy of Sciences.
Those who started using cannabis in adolescence and used it for years afterward showed an average decline in IQ of 8 points when their IQ tests at age 13 and age 38 were compared.
When you are as remarkably clever as Alf you could afford to lose a few IQ points and be reduced to clever.
But for most folk, losing those eight points is big deal and turns them into clods.
Quitting pot accordingly seems to be a clever thing to do, but if you have been smoking it for too long you won’t be clever and presumably won’t quit.
Anyway, quitting isn’t going to help things much.
The research found it did not appear to reverse the loss, lead researcher Madeline Meier, a post-doctoral researcher at Duke University, is quoted as saying.
The key variable was the age of onset for marijuana use and the brain’s development, Meier said.
Those who did not take up pot until they were adults with fully-formed brains did not show similar mental declines.
Before age 18, the brain was still being organised and remodelled to become more efficient, and may be more vulnerable to damage from drugs.
The Stuff story goes on to say about 5 per cent of the study group were considered marijuana-dependent, or were using more than once a week before age 18.
A dependent user is described as one who keeps using despite significant health, social or family problems.
At age 38, all study participants were given a battery of psychological tests to assess memory, processing speed, reasoning and visual processing.
The people who used pot persistently as teens scored significantly worse on most of the tests.
Friends and relatives routinely interviewed as part of the study were more likely to report that the persistent cannabis users had attention and memory problems such as losing focus and forgetting to do tasks.
We are told that somebody who loses 8 IQ points as an adolescent may be disadvantaged compared to their same-age peers for years to come.
Alf has always been puzzled by the behaviour of people who are not clever enough to want to join and support the National Party.
Many of these not very clever people become Labour and Green Party politicians and supporters.
We now have an explanation for this phenomenon.