Smoking Could Alter Teens' Brain Structure

It’s common knowledge that smoking cigarettes is bad for your health, but young people are still choosing to light up more than any other demographic in the United States. Researchers now have evidence that a specific part of the brain varies between smokers and nonsmokers. The researchers say it could be that smoking is causing these changes, even in teenagers who have smoked for a relatively short period of time.

Prior research has shown brain differences between adult smokers and nonsmokers, but few studies focused on the youngest demographic of smokers whose brains are still undergoing development. The new findings indicate that a small part of a brain region called the insula is thinner in young people who smoke.

The insula is a part of the cerebral cortex, and it is involved in shaping our consciousness and emotions. The insula also houses a high concentration of nicotine receptors and plays a critical role in generating the craving to smoke. The study’s lead researcher Edythe London said they focused on this particular part of the brain because previous studies in adults and mice showed its size and volume were affected by smoking.

To test differences in the insula of young smokers, London and her colleagues used structural MRI to compare the brains of 18 smokers and 24 nonsmokers between the ages of 16 and 21. The average age smokers started the habit was 15, and they averaged six to seven cigarettes a day.

The brain scans showed that thickness of the insula, on average, was not substantially different between the groups. However, the thickness of a smaller part of the insular region, the right insula, was negatively related to cigarette dependence. Individuals who had smoked for longer, or had stronger urges to smoke, had a thinner right insula. The team published their findings this week in the journal Neuropsychopharmacology.

“It looks like, even in these very young kids, there is a link between the structure of the insula and the extent to which they smoke and become dependent,” London said in a Neuropsychopharmacology podcast. “It was shocking. We are beginning to get a story of the functional neuroanatomy of smoking.”

Although the study illustrated a difference in brain structure of young smokers and nonsmokers, it did not establish whether smoking caused the variations. It could be that people with differently structured insulas are more likely to take up smoking for an unknown reason. However, the results pave the way for future studies to determine the actual cause and effect.

“Ideally one would start the study in 12-year-olds who haven’t begun to smoke; follow them out after they begin to smoke; and see if in fact the smaller insula thickness was a predictor of a predilection to become a smoker,” London explained in the podcast.

On the other hand, if London’s team finds proof that smoking causes thinning of the right insula, it would provide further evidence of the detrimental health effects of picking up the habit at a young age. 

Photo credit: Dora Zett/Shutterstock

View the original article here

Baby Brain Scans Predict Later Cognitive Development?

The shape of a newborn baby’s brain can predict its later cognitive development, according to a new study from New York neuroscientists Marisa Spann and colleagues.

Here’s the paper: Morphological features of the neonatal brain support development of subsequent cognitive, language, and motor abilities

Now, while the word ‘phrenology‘ gets banded around a lot these days by people who don’t like neuroscience, this study actually sort of fits that description – except instead of ‘bumps on skulls’ it was more ‘bumps on brains’. The authors scanned 48 babies (within 6 weeks of birth) using MRI to obtain an image of brain structure; they then analyzed the shape of each brain using a deformation-based morphology approach.

This revealed areas on each brain that were bigger or smaller than the average newborn brain:

The outputs were a set of local ‘indentations’ and ‘protrusions’… or, one might say, troughs and bumps? Anyway, after being scanned, the babies were followed up for two years and tested every 6 months to measure their developmental functioning in the domains of motor, language, and cognitive skills (using the Bayley-III scale.)

There were significant correlations between brain shape and later development, however interestingly, most of these were negative correlations – that is, infants with a thinner cerebral cortex in each particular area did better:

Here for example you can see results for the cognitive domain at ages 6, 12, 18 and 24 months. There are correlations in many areas, mostly negative (purple blobs), with the exception of some positive (yellow) correlations in the occipital cortex but these areas only predicted performance at 6 months.

So it would seem that in general, ‘less is more’ for many parts of the newborn brain. Which is interesting because in a previous study, as the authors write,

At birth, head circumference as a proxy for brain volume was the strongest (positive) predictor of intelligence at 4 years (Gale et al 2006).

Spann et al don’t seem to have analyzed whole-brain volume, but why would regional cortical thickness be a negative predictor of development? They suggest that it might be a slow-and-steady-wins-the-race type deal:

Slower or more protracted maturation of the brain or brain subregions, that are otherwise growing rapidly specifically in the neonatal period, may support the development and emergence of improved motor, language, and cognitive abilities in later infancy.

However… the sample size wasn’t huge. Although they scanned 48 babies, only 37 had usable MRI data (for the other 11, quality was too poor). And of those, they were only able to get developmental assessments on n=33 at age 6 months, falling to n=18 by 24 months. A decently sized study at the outset, it had become a decidedly small one by the end.

And I do worry (as I always seem to these days) about head movement. It’s hard enough to get adults to lie still in an MRI scanner. With babies it’s all but impossible which is why the authors used the special motion-resistant T2 PROPELLER sequence. However, they still had to throw out about a quarter of their scans, perhaps for excessive motion.

Could the scans they included have been degraded by movement, perhaps correlated with baby temperament and later behaviour, and could this have confounded the deformation-based morphology? Spann et al say that “the similarity transformation of an infant brain to a template is robust to the presence of noise in the imaging data” but it would have been nice to see some quantitative checks of that assumption.

Spann, M., Bansal, R., Rosen, T., & Peterson, B. (2014). Morphological features of the neonatal brain support development of subsequent cognitive, language, and motor abilities Human Brain Mapping DOI: 10.1002/hbm.22487

View the original article here