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The Limits of Neuroplasticity

I am daily annoyed by overhyped headlines reporting medical and other science news. I think news outlets and the public would be better served if they fired all their headline writers and let the authors and editors craft headlines that actually reflect the story. Of course, often the story is overhyped as well, so this would not be a panacea to annoying science reporting.

Take this headline from The Week (please): “This pill could give your brain the learning powers of a 7-year-old“. The article discusses a recent study (full article here) looking at the effects of a drug, valproic acid, on the ability of young adult male subjects to learn pitch. It might be a good exercise for regular SBM readers to take a look at the full article now and analyze the strengths and weaknesses of the study.

The study found that those subjects taking valproic acid, which is a drug used to treat seizures, migraines, and mood disorders, did slightly better overall in learning to identify the pitch of various tones. The main limitation of the study is that it is very small – 24 participants enrolled, 18 completed. Further, they did not establish a good baseline performance, as the subjects were practicing as they went along.

There are other limitations but these are enough to classify this study as preliminary. It’s an exploratory study that should only be used to decide upon later studies. In my opinion, it should not be reported to the public at all – or if it is, it should be made abundantly clear that these results are so preliminary we cannot conclude anything from them.

If the effect is real, however, what could it mean? It does not mean valproic acid gives you the learning ability of a 7 year old. Perfect pitch is being used as a research paradigm to look at learning windows – periods of time where people have a much greater ability to learn some skill or ability (language, or perfect pitch, for example), and also where later that window closes and learning that skill becomes much more difficult. Researchers are trying to figure out the neurological mechanism of such windows.

If valproic acid has some effect on such learning, it might provide a clue as to the underlying mechanism. The authors of this study conclude:

In sum, our study is the first to show a change in AP with any kind of drug treatment. The finding that VPA can restore plasticity in a fundamental perceptual system in adulthood provides compelling evidence that one of the modes of action for VPA in psychiatric treatment may be to facilitate reorganization and rewiring of otherwise firmly established pathways in the brain and its epigenome

I think they are overstating their conclusions. I would have thrown in at least a “possibly” in there, given the extremely preliminary nature of their results. But again, assuming the results hold up, it is reasonable to speculate about mechanisms.

I would also note that valproic acid is a serious drug with serious side effect, including sedation, weight gain, and foggy mentation. As an anti-seizure drug it also carries the possibility of withdrawal seizures if stopped suddenly. I doubt it would have a net cognitive benefit if taken regularly, which is another reason why I am suspicious of the findings of this study.

This is exactly why I am concerned about the hyped reporting of such preliminary studies to the general public. If this were a supplement rather than a prescribed drug, you bet you would be hearing about it on Dr. Oz, and products would be popping up on health food store shelves.

Posted in: Neuroscience/Mental Health

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