What’s an appropriate control group for a schizophrenia study?

The researchers who did the Our long-term memory usually selects what we pay closer visual attention to study were back zapping subjects’ brains again in this 2015 human study.

From news coverage of the study, prior to zapping the subjects’ brains:

“In healthy individuals, these theta waves were steady and synchronized, but in people with schizophrenia, the waves were weak and disorganized, suggesting that they were having a harder time processing the mistake. And the subjects’ behavior bore that out—the healthy subjects slowed down by a few milliseconds when they made mistakes and did better in the next round, while the subjects with schizophrenia did not.”

The processing of an appropriate control group wasn’t clear to me from reading the supplementary material. The subject patients were diagnosed with schizophrenia and took psychoactive medication which the researchers equated to chlorpromazine dosages. The control group subjects had neither the condition nor were prescribed the medications.

How did the researchers differentiate the influences of psychoactive medications on the experimental results from the influences of the subject patients’ conditions?

Were there numerical calculations not shown in the supplementary material that somehow nullified the effects of psychoactive medications?

To be sure that the zapping was effective for the subject patients’ conditions, wouldn’t the control group subjects need to take the same medications so that the experimental data reflected only the differences attributable to schizophrenia?

The researchers also asserted:

“Causal changes in the low-frequency oscillations improved behavioral responses to errors and long-range connectivity at the single-trial level.”

However, brain waves can’t be termed as base causes of human behavior. Studies such as:

clearly established that brain waves are effects of base causes.

Was there something that stopped the researchers of this study from investigating the generating sources of brain waves? Was it that they work in the same Vanderbilt University department as the researchers of A study of visual perception that didn’t inform us about human conscious awareness, and were similarly biased against brain research that may lead to finding evolutionary biological causes for human behavior?

http://www.pnas.org/content/112/30/9448.full “Synchronizing theta oscillations with direct-current stimulation strengthens adaptive control in the human brain”


One thought on “What’s an appropriate control group for a schizophrenia study?

  1. Thanks, Nick!

    As you said, giving the same psychoactive medication to the control group subjects as the subject patients take would likely cause cognitive deficits in healthy people. When the researchers stated “..it is unlikely that the effects we observed are simply due to the presence of antipsychotic medication” they’re just making up things with numbers, in my view. The reality of psychoactive medication is different.


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