Friday 13 February 2015

Cigarettes, booze and beautiful women: the thin cut

From an early age, beautiful women plied me with cigarettes and alcohol. I can still remember their alluring scarlet-painted nails and perfectly tailored close fitting skirts as they reached towards me in a cloud of perfume, with bottles of whiskey and Salem menthol cigarettes in their immaculate hands. To add to the drama, there were clouds of the usual sort scudding past the windows of the battered DC-3 Dakotas and Short Sunderland flying boats I used to take between Buenos Aires and Montevideo, and air hostesses in close proximity could not fail to make a sensual impression on a 12 year old boy, sexual urges augmented by the excitation transfer of a bucketing aircraft with uncertain shuddering propellers battling thunderstorms across the River Plate.

By every environmentalist theory I should have been a natural drinker and smoker, with a perfect alibi for my excesses. Instead, I dutifully handed over the miniature bottles and 5 cigarette courtesy packs to my grateful parents. In later years I tried a few cigarettes, but they failed to ensnare me, and so I was never burdened by habits of the chemical sort.

Many other youngsters were not so lucky, and took up the seductive attraction of an illicit pleasure. Sure, it puts you at risk of lung cancer and general ill health, but why should it influence intelligence, when booze and fags are an intellectual’s necessities, or at least have often been touted as such, by intellectuals themselves if not by their doctors?

Some of you may be tired of hearing from the Craigleith sandstone citadel of Edinburgh, but I cannot stop the gang in that place from churning out interesting stuff. They find that smoking thins the brain, even when you allow for prior intelligence and other confounders, and that giving up smoking makes things better, but it takes the brain a long time to recover lost ground. It is a thin cut, but every millimetre counts.

Karama; Ducharme; Corley; Chouinard-Decorte; Starr; Wardlaw; Bastin and Deary (2015) Cigarette smoking and thinning of the brain’s cortex. Molecular Psychiatry advance online publication, 10 February 2015; doi:10.1038/mp.2014.187

They say:  Cigarette smoking is associated with cognitive decline and dementia, but the extent of the association between smoking and structural brain changes remains unclear. Importantly, it is unknown whether smoking-related brain changes are reversible after smoking cessation. We analyzed data on 504 subjects with recall of lifetime smoking data and a structural brain magnetic resonance imaging at age 73 years from which measures of cortical thickness were extracted. Multiple regression analyses were performed controlling for gender and exact age at scanning. To determine dose–response relationships, the association between smoking pack-years and cortical thickness was tested and then repeated, while controlling for a comprehensive list of covariates including, among others, cognitive ability before starting smoking. Further, we tested associations between cortical thickness and number of years since last cigarette, while controlling for lifetime smoking. There was a diffuse dose-dependent negative association between smoking and cortical thickness. Some negative dose-dependent cortical associations persisted after
controlling for all covariates. Accounting for total amount of lifetime smoking, the cortex of subjects who stopped smoking seems to have partially recovered for each year without smoking. However, it took ~ 25 years for complete cortical recovery in
affected areas for those at the mean pack-years value in this sample. As the cortex thins with normal aging, our data suggest that smoking is associated with diffuse accelerated cortical thinning, a biomarker of cognitive decline in adults. Although partial recovery appears possible, it can be a long process.

As you may know, I do not show pictures of brains on this blog, because they are apt to convince innocent readers of just about anything, but I urge you to make an exception for those created by Mark Bastin, which I am sending you under plain cover and you will find on pages 4, 5 and 6 of the paper.

https://drive.google.com/file/d/0B3c4TxciNeJZZGlyOE1OdlJnWlE/view?usp=sharing

However, I can reveal the picture that is worth 1000 words below, showing the full cost of cortical thinning for late quitters and current smokers:

 

 

image

 

"Smoking," wrote two-pack-a-day Jean Paul Sartre long before dying of lung failure at age 74  is "the symbolic equivalent of destructively appropriating the entire world." Perhaps those old smoke-wreathed intellectuals were dulling their bright minds with their habits, even though they could still turn a phrase which sounded profound. What damages the brain more: smoking or being a French Intellectual?

13 comments:

  1. Here's my favorite passage from this study:

    "A limitation of this study is its observational nature. Further, one needs to be cognizant of the possibility that reverse causation may account for a certain amount of the association between smoking and cortical thinning. For instance, we show that IQ at 11 years accounts for a certain degree of association between smoking and cortical thickness (Supplementary Figure S1). This supports the view that a certain proportion of the cortical thickness/smoking association is not due to direct or indirect effects of cigarette smoking on the cortex given that those with a lower IQ have both a thinner cortex16,36 and a higher propensity to smoke.2 Similarly, structural differences in cortical areas related to impulse control (for example, the orbitofrontal cortex) might predispose to smoking and therefore predate it rather than follow from it.37 This being said, the identified dose-dependent associations
    in diffuse brain areas (including regions without evidence for a role in impulse control) and the apparent reversal of the effect of smoking on the cortex provide evidence that the differences in thickness do not mostly predate the onset of smoking."


    How the hell did they come to that conclusion? A "dose-dependent" relationship certain doesn't rule out reverse causation, among other things. Because they're results were attenuated when they took childhood IQ into account, this suggests measurement error (as explained previously) could explain all their results. But then, even if this is real, there's nothing saying they simply got the direction of causation ass-backwards, as stated. After all why did these smokers continue to smoke so long? Or, to phrase it in HBD Chick's terms, where does a long-term smoking habit come from?

    Oh, and how monoethnic was their sample? They don't seem to mention race in the study, or maybe I missed it?

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    1. The sample is mono-ethnic, and was taken long before large scale non-european migration coming to Scotland, which it did relatively late. I do attach importance to the fact that those who gave up smoking early show less effect. Life is not pure experimentation, but to me this looks like a consequence of a change in behaviour.

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    2. "I do attach importance to the fact that those who gave up smoking early show less effect."

      But would this not be what we'd expect if those brain structures were driving smoking behavior and its persistence?

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  2. Filthy habit, smoking cigarettes. But a pipeful of Balkan Sobranie - that's a civilised and civilising experience. Alas, not experienced by me these forty years. And I'm a one-glass-of-pop a day man. I conclude that if there is such a thing as an addictive personality, I don't have it.

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    1. Except perhaps for points of grammar. Would anyone prefer "if there be such a thing as ..."? Archaic, perhaps?

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  3. I think persistent vicious born during adolescence when the brain is finish its maturation. I think higher iq ( and adhd people) is relatively more prone to vicious because both tend to mature slowly, adolescence is a final period of experimentation.
    I hate cigarette in part because my father who smoking since their 12 year old. I pass this feeling to my gifted ( simmmetrical intelligence, typical termite) cousin. My two brother are marijuana lovers.

    Santoculto

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  4. "What damages the brain more: smoking or being a French Intellectual?" The only FI I've ever known was guilty of aggravated primping.

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  5. How does cigarette smoking while pregnant affect the child's developing brain?

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    1. But some, perhaps...http://pediatrics.aappublications.org/content/early/2014/07/16/peds.2014-0213.full.pdf+html

      The studies used different definitions for academic functioning. The Pediatrics study looked for ADHD diagnoses, medication, or descriptions consistent with ADHD. Maternal smoking status seemed to have a stronger effect than paternal smoking status.

      If people with different IQs have different levels of cortical thickness at the same point during childhood, (http://www.nih.gov/news/pr/mar2006/nimh-29.htm) then the effect of smoking (if it thins infant brains) would be hard to discern on different individuals. You'd have to start the study at a time at which you can assume everyone should have the same cortical thickness. Except many people start smoking during their teen years, while their brains are developing.

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  6. http://www.religjournal.com/pdf/ijrr10001.pdf

    Interesting.


    Santoculto

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  7. interesting that users of tobacco products are less likely to get alzheimer's disease...and nicotine has been shown to reduce symptoms of AD

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  8. http://abcnews.go.com/Health/AlzheimersNews/nicotine-patch-improves-memory-people-mild-cognitive-impairment/story?id=15323012

    I have convinced my mother to start using the Nicotine patch (she is 71 years old) since her parents started to show signs of AD when they were in their 90s.

    Research at Lancaster University has developed two new techniques to measure the size and rate of development of the clusters of beta-amyloid in the very early stages. This has enabled researchers to test a number of substances to see if any of them could slow down or prevent the development of the plaques.
    Two of the substances tested threw up intriguing results. The first was nicotine, which was observed to hinder plaque formation

    http://www.jyi.org/issue/nicotinic-acetylcholine-receptors-and-alzheimers-disease-therapeutics-a-review-of-current-literature/

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