Ouch. Turns out football isn’t very good for your brain.

May 20th, 2014

Dang it. I’ve felt guilty about liking boxing for a while, and it looks like I’m going to have to feel guilty about liking football now, too. Last week a study was published in the Journal of the American Medical Association that makes a pretty interesting case for steering your boys toward other sports, like curling or synchronized swimming or something. The study’s authors, researchers at the Laureate Institute for Brain Research in Tulsa, Oklahoma, compared MRI scans of brains of NCAA football players, 25 of which had a documented history of concussions, and 25 of which had no reported history of concussions. They also added a control group, consisting of 25 young men matched for age and education.

So, this study was like the marijuana one, in that it compared the volume (size, in three dimensions) of particular brain structures between an identified group and a comparison group. Turns out it was similar in another way, too: the good ol’ hippocampus drew the short straw again and had to be the structure that got shrunk. Specifically, the football players had smaller hippocampi (that’s plural for hippocampus—because “hippocampuses” is just way too silly to say at academic meetings) than the matched controls. In fact, those with no concussion history had hippocampi that were, on average, about 15 percent smaller than the controls’ hippocampi. And as for those who had a concussion history, theirs were a whopping 25 percent smaller than the controls’. The differences among all three groups were significant from one another, for both the left and the right hippocampus. And that’s not all: there was a significant negative correlation between left hippocampus volume (but, oddly, not right) and the number of years of tackle football that had been played. That is, for every year of football played, the left hippocampus was that much smaller.

So it seems that all the physical roughness of the game results in cumulative injury to the brain. This is most vividly the case when people actually suffer from a series of concussions, but, importantly, this study suggests that the absence of concussions doesn’t mean the brain has not been damaged by the repeated forces associated with playing tackle football. The damaging effects of repeated concussions has been very much in the public eye for the last few years, resulting in some serious soul-searching in the world of competitive sports. This study adds to the literature in support of greater caution around head injury in sports, and raises the sobering idea that subtle damage may come about even when there is no history of overt symptoms.

Friends, I’m told, don’t let friends do drugs. Maybe they shouldn’t let friends play rough sports, either. Golly, how are we gonna have any fun?

Casual marijuana use among young adults leads to structural brain abnormalities

May 14th, 2014

Came across this study published last month in the Journal of Neuroscience. The study’s authors, led by Jodi Gilman of Harvard Medical School, looked at whether marijuana, used in typical quantities, is associated with any structural brain changes among users between the ages of 18 and 25. Previous research had shown that administration of THC (the psychoactive component of marijuana) to rats results in brain changes, and that extremely heavy use among humans can also lead to brain abnormalities. However, to date no studies had shown whether more typical usage patterns among young human adults were associated with any brain changes.

The authors compared MRI scans between 20 casual marijuana users and 20 other young people, matched to the marijuana group on the usual demographic variables. They found—perhaps remarkably considering the small sample—pronounced differences between the marijuana group and the matched controls. In fact, every single member of the marijuana group, even those who smoked pot only once a week, showed the same pattern of structural brain differences from the control subjects. Furthermore, these brain differences were correlated with usage patterns, such that they were more pronounced among those who used the drug more frequently.

The specific differences were that the users exhibited greater grey matter density (more cells packed into a given volume) in the left nucleus accumbens and the surrounding cortex, including the hypothalamus and the left amygdala. They also showed abnormalities in the morphometry (shape) of the left nucleus accumbens and right amygdala. Now, these are not structures that one wants to mess around with. They’re critical for the processing of information related to emotion and motivation, and the nucleus accumbens in particular is associated with the generation of reward motivation – that is, the ability of a reward stimulus to influence future behavior aimed at achieving further reward. The amygdala, of course, is important for the shaping of emotional experience, as well as the influence of emotional experiences on behavior.

We seem to be on a steady track toward the full mainstreaming of marijuana in our society. The drug is being used extremely widely now, especially among teens, and in popular culture it’s consistently portrayed as a harmless form of recreation. Legislatures are under pressure to legalize its use, the outcome of which now seems to be pretty much a foregone conclusion. But this study shows that marijuana is a more powerful and potentially damaging substance than is generally thought. The study suggests that even light use brings about quite profound changes in brain structure (and, consequently, in brain function). Moreover, the anatomical structures affected by the drug line up, in kind of a scary way, with the most frequently made behavioral observations about pot users: that they seem blunted in their motivation, unambitious, listless. I’ve seen these qualities in many of my own clients who use marijuana.

Listen, it’s easy to think of those qualities as charming and entertaining. So many movies have a lovable-pothead character who is portrayed as almost a personification of the drug itself: fun, mostly harmless, kind of goofy.

But what if the brain changes that are brought about by even casual pot use result in serious motivational deficits, deficits that make it harder for the person to persist with his studies, to enjoy life when not high, to think, remember, and make decisions? How will that affect individual lives? How will it affect relationships, the workforce, the economy? Zoinks!

See what I mean about consent being flimsy?

April 8th, 2014

Not about the brain at all, but it illustrates the point I made in my last post. Belgian physician calls for euthanasia to be applied without the need for such cumbersome requirements as, you know, the patient actually agreeing to it. It’s in French, but Google translate makes it partially intelligible.

Mind-reading, one step closer…

April 8th, 2014

Whoa, this is an interesting study. Just out in NeuroImage, Yale undergraduate (undergraduate, mind) Alan S. Cowen, along with supervisor Marvin M. Chun and postdoc Brice A. Kuhl, developed an algorithm for capturing the features of human faces mathematically, then observed evoked brain activity while people were viewing those faces, correlating the neural activity in various regions with the face features. They subsequently used brain activity to reconstruct and identify, from the brain scans alone, which of another set of faces people were looking at. Freaky, eh?

This study goes well beyond previous studies in which researchers managed to identify what people were looking at on the basis of their brain activity, because distinguishing among different human faces requires a lot more sophistication than distinguishing, say, between an animal and a building. The study also stands out because it used brain activation from a large number of brain regions, rather than just from the parts of the brain representing the early, elemental stages of visual processing. Faces, because of their behavioral importance, evoke strong neural responses in various areas outside of those dedicated exclusively to early-stage visual processing.

Listen, it’ll be a while yet before anyone can read your mind, but it’s starting to look like such a thing may be possible in the future—and maybe not even that far into the future. All this highlights the increasingly dire need for a robust neuro-ethics. As in other areas of scientific inquiry—put perhaps uniquely so when dealing with the seat of human reason, emotion and judgement—it needs to be not only a question of what can be done, in a technical sense, but of what ought to be done, or ought not to be done. We now have studies (I’ve reviewed some of them here!) that show that simple brain stimulation can alter people’s preferences, increase or decrease the likelihood that they will behave in an altruistic manner, make them self-focused or other-focused, evoke or bury or alter memories, &c., &c. How long until there are “clinical” applications of this, in which people’s preferences, judgements, even qualities of moral decision-making can be “treated” by those who are more correct and more enlightened than they are?

I find all of this very unsettling, because our culture, perhaps more than any other in human history, is completely adrift with respect to the meaning and foundation of ethics. We have much-vaunted technical know-how, but at the same time we’re awash in a corrosive postmodern soup of relativism, which the naïve imagine means that everyone is free to make his or her own reality, but which really means that everyone is free to subscribe to the reality established by the most powerful among us, for their own purposes. In one absolutely bone-chilling example, last year we had academics making the serious proposal, in a serious journal of “medical” “ethics”, that infants whose parents don’t want them ought to be able to be killed, and that this killing should henceforward have the imprimatur of correctness from our priestly class of professional academics. “Post-birth abortion”, they call it. The old word for it—murder—was much more straightforward, and more honest.

What passes for ethics today rests entirely on the extremely flimsy foundation of “consent”, which is laughable even when you don’t consider the fact that “consent” can now in principle be altered by the application of a mild electric current or a train of magnetic pulses over the right brain areas. Just at the time when we are most in need of sober, well-grounded ethical thinking, we find ourselves incapable of doing anything like that sort of thinking.

Into every life a little rain must fall…

March 17th, 2014

…but can you please just refrain from posting about it on Facebook? Because it bums me out. And it’s sunny here.

This recent study, published in the journal PLOS One, put together weather data and Facebook posts in American cities. The authors wanted to test a few hypotheses having to do with the impact of a variable like weather not only on people’s state of mind, but on the state of mind of members of their social network. First, they determined that people’s Facebook posts on rainy days tend to be less positive in tone than on non-rainy days. Specifically, on rainy days there were 1.19 percent fewer positively toned Facebook posts, and 1.16 percent more negatively toned posts, than on non-rainy days. That in itself isn’t terribly surprising, except maybe that the effect is pretty small. Indomitable folks, those Americans. Besides, they’re not gonna stop the rain by complainin’, am I right?

Anyway, that wasn’t the interesting part. This was the interesting part: on those same days, people’s positive and negative posts were impacted by the weather in their friends’ cities. Based on the models they constructed from the data, the authors estimated that a rainy day in New York City directly results in an extra 1500 negative posts by New Yorkers, and also results in about an extra 700 negative posts by their Facebook friends in other cities, irrespective of the weather there. Here’s a figure from their study that shows, for each city, the effect of rain in that city, as well as the (indirect) effect of rain when it happens elsewhere.

This is all direct evidence of an emotional contagion effect that occurs across social networks, and the authors argue that social media may serve to amplify natural social contagion effects by giving people more and quicker access than they would otherwise have to the emotional states of other people, even people who are miles away. This, they speculate, may result in “greater spikes in global emotion that could generate increased volatility in everything from political systems to financial markets”. Boy, that’s not at all scary, is it?

Diffusion-weighted MRI image of the human brain

March 12th, 2014

This picture shows up as a finalist in the Wellcome Image Awards for 2014 (check out the rest, they’re cool!). It shows an image of the connecting fibres in the human brain (I mentioned those in my last post), captured using MRI diffusion-weighted imaging. This type of imaging captures the position and direction of fibres in the brain by capitalizing on the fact that water molecules move more easily along fibres than across them. In the image the front of the head is to the right, and the left side of the head is at the top. The fibres are colour-coded to show you their direction in three dimensions: green ones run front to back along the main axis of the brain, red ones run left to right between the ears, and blue ones run top to bottom, between crown and neck. I don’t know about you, but I find images like this breathtakingly beautiful:

Diffusion weighted imaging has been an important tool recently, as neuroscience has enlarged its emphasis from the functions of particular brain structures to the way these structures are joined together, structurally and functionally, into networks. Scientists identify these networks structurally using imaging such as is shown here. They also have some cool ways of identifying them functionally, by noting which parts of the brain tend to wax and wane together across time in their oxygen uptake while a person is lying in an MRI scanner and doing some sort of task. The premise is that areas that consistently “light up” (become active) together are working together.

There’s been a lot of really neat work in this area, with several networks now reliably identified and characterized in terms of their participating brain areas and their probable functions. For example, there’s the pioneering observation of a network called the Default Mode Network, which was first characterized when neurologist Marcus Raichle and colleagues noticed that the brain always seems to be shutting off the same areas when people are in the scanner doing an experimental task. Raichle got curious about these areas, and found that they’re active when a person is not asked to engage in any task in particular, but simply lying still in the scanner. More recent work has shown that the DMN isn’t just an idling state, though: it also activates in some states of focused but inwardly-directed attention, such as thinking thoughts about oneself or recalling autobiographical events. The other thing about the DMN that’s really interesting from the perspective of psychopathology and neurology is that a lot of clinical conditions are associated with a failure to deactivate the DMN when it’s supposed to quiet down and let other, more externally directed networks do their thing. It just keeps chugging along, interfering with the external allocation of attention, which researchers think may be why so many different conditions have impaired atttention as one of their features.

Thinning of cortex correlates with changes in IQ

March 5th, 2014

This article describes a recent multi-site study that measured changes in children’s brains as they aged, and correlated those changes with increases or decreases in their general intelligence, as measured by their IQ. The study was published in January in the journal NeuroImage by Miguel Burgaleta, Wendy Johnson, Debra Waber, Roberto Colom and Sherif Karama. The authors compared the thickness of the brain’s cortex in children and adolescents at a two-year interval, to provide a snapshot of their development at those two time points. Cortex is Latin for “bark”, as in tree bark. It refers to the outermost layer of brain tissue, which is grey in colour and distinct from the white matter that lies underneath it. The cortex is basically where most of the computational action happens in the brain. Much of the remaining brain tissue enclosed by this “bark” consists of fibres connecting cortex to cortex, cortex to deep brain structures, and cortex to the rest of the body.

As adolescents develop, the thickness of their cortex generally decreases, a process of refinement that supports their ongoing development. What this study showed was that some people have more thinning than others in particular brain areas. Those who had moderate thinning in those areas (mostly on the left side of the brain, in front of the sensorimotor strip) maintained a similar IQ score across the two-year gap, while those who had extreme thinning showed a drop in IQ scores across the two-year interval. Interestingly, some had no thinning at all, or even a little bit of thickening, and these individuals showed increases in their IQ across the two-year period. Here’s a figure from the study showing which part of the brain showed correlations between cortex thinning and IQ changes, and what those changes were for the various IQ change groups (those who showed a decrease in IQ, stable IQ, or an increase in IQ).

The implications? Well, there are a few. One is that IQ isn’t always stable across time—although we psychologists generally assume that it will be, and that any changes we do see are the result of random measurement error. It appears that people sometimes actually get smarter, or less smart, and that these changes have real, solid neurological reasons behind them. Another is that the left frontal cortex seems particularly associated with intelligence, more so than other brain areas, although there is obviously a lot of contribution from a lot of intracranial neighbourhoods.

Best of all, I will now have a ready answer the next time my wife refers to me as being “a little bit thick in the head”.

More beauty. Sort of.

February 28th, 2014

Just saw this little bit in Scientific American. It summarizes a study published last fall in the journal Social Cognitive and Affective Neuroscience by a team of Italian researchers. In the study the researchers found that stimulating the left dorsolateral prefrontal cortex (lDLPFC) with transcranial direct current stimulation (tDCS – sorry, alphabet soup today) led to changes in their judgements of the aesthetic beauty of things they were looking at.

Specifically, the researchers had subjects rate how much they liked each of a set of paintings and photographs, then undergo either real or sham (fake) tDCS for 20 minutes, then re-rate their liking for the pictures. tDCS is a fascinating bit of cheap, simple technology that allows noninvasive stimulation of a particular bit of brain real estate, by passing a very small DC current through an electrode held against the scalp. Anyway, these folks sat and watched a movie for 20 minutes while having their left DLPFC either stimulated for real, or hooked up to a stimulator that was shut off soon after it started; then they re-rated the pictures. The result was that they liked the pictures better after real stimulation than before, but their ratings didn’t change after they received fake stimulation. Interestingly, the effect only held for representational art or photography (i.e., pictures of, you know, actual stuff), but not for abstract art. Which kind of confirms what I’ve always thought about how possible it is to actually like abstract art. Even with neuro-enhancement you can’t quite get there.

Now, the site of stimulation was particularly interesting. The left DLPFC is a favourite target for interventions aimed at increasing positive emotion. It remains the main go-to target for repetitive transcranial magnetic stimulation (rTMS – I know, more letters) for depression. Neurofeedback protocols aimed at increasing activation of left-hemisphere structures, and particularly the left DLPFC, have also shown promise in relieving symptoms of depression. So it seems that there’s a connection between positive affect in general and aesthetic appreciation in particular. I don’t know much about all that. But I know what I like.


February 19th, 2014

Here’s another infographic. This one’s on dementia, and it’s very informative. Dementia is shaping up to be the public health issue of the next several decades. We have a huge number of people entering old age in the next little while, and that means a lot of dementia. As the graphic shows, dementia requires a great deal of intensive supervision and expensive health services, not to mention a lot of patience and love on the part of family members.



Another new study shows that neurofeedback is effective for ADHD

February 18th, 2014

Here’s another study that shows how a venerable neurofeedback protocol that’s been around for quite a while (enhancing EEG wave activity in the Beta frequency while suppressing activity in the Theta frequency) reduces symptoms of inattention and hyperactivity among children with ADHD. Check it out, and take a look around the SharpBrains website while you’re at it! It’s a treasure trove of information about what works and doesn’t work when it comes to brain health and cognitive fitness.