How often do you read a headline declaring that “such-and-such changes the brain”? Observed brain differences have been ascribed to everything from video games to cocaine to meditation. Here are some examples:
Statements like these bother me for three reasons. First, they assume that the thing-in-question has caused brain changes, when, frequently, the study can make no such claim. The fact that people who engage in some activity—say, playing video games—have brain differences when compared to others does not mean that the activity is responsible for those differences. It is equally likely that the pre-existing brain differences lead certain people to enjoy the video games more, for instance. Most of the cited studies that investigate brain differences are not longitudinal studies—they compare the brains of two groups of people, rather than actual changes over time, so it is impossible to tell whether the thing-in-question caused the changes observed. And even longitudinal studies do not prove causation, since it is almost always impossible to control for all other lifestyle factors.
One area of discussion in which this point is especially relevant is drug addiction. Brain scans of addicts unquestionably differ from those of non-addicts. However, the fact that only a small percentage of drug users actually develop an addiction suggests that there might be something already different about this particular population. Simply blaming the drug—“cocaine changes the brain!!”—overlooks this possibility, and does nothing to elucidate the actual nature of addiction.
Second, these statements assume that the observations have some relevance to health or society; usually, they make a judgment call as to whether the brain-changing thing is good or bad, precisely because of the changes it supposedly induces. In reality, the observation of brain changes does not necessitate concern or enthusiasm, yet it is frequently met with such reactions. “Because using the Internet changes the brain, we should worry more about kids spending so much time online” or “if meditation actually changes the brain, maybe it really would solve my problems”. These reactions in themselves already depend on preconceptions regarding the thing-in-question. Does the brain-changing power of video games make children more violent, or does it improve their working memory or coordination? Indeed, more than likely, the brain changes will not even have any noticeable behavioral effect.
Third, such headlines imply that the thing-in-question warrants unique attention because of its brain-changing power. Yet, the idea that something-or-other causes changes in the brain is meaningless, hardly interesting. Of course it changes the brain, because the brain is always changing, and every single experience induces some measurable change. So, that statement of “cocaine changes the brain!!” is of no scientific interest on its own; on the contrary, it would be more surprising to find a drug or experience that has no effect whatsoever on the brain. The mere observation that something “changes the brain” doesn’t reveal anything about the brain-changing thing.
With our collective knowledge of the brain so rapidly increasing, I understand the temptation to use neuroscience as evidence to support our claims. I would be thrilled if we could pinpoint the neural basis of every action, every thought, and explain how each experience molds the development of our minds. However, we have to be careful, lest we see monsters where there are none.