Tag Archives: Electric current

Why we should be skeptical of miracle cures: A case study

15 May

An article by Keith Humphreys titled: “What can we learn from the failure of yet another ‘miracle cure’ for addiction?” Here is the summary:

“The first long-term double-blind study of PROMETA has demonstrated that this putative miracle cure for methamphetamine addiction is ineffective. Given the vulnerability of addicted people and their desperation for a cure, effective governmental regulation and a shared spirit of skepticism about ‘wonder drugs’ should always be maintained.”

I think this is good advice, not just for claims for addiction cures, but for all claims for human enhancement. Keep an open mind, but demand good evidence.


Transcranial direct current stimulation decreases performance on intelligence test

7 May

The other day, I linked to a popular account of this story. Here is the abstract for the original paper:

Transcranial direct current stimulation (tDCS) modulates excitability of motor cortex. However, there is conflicting evidence about the efficacy of this non-invasive brain stimulation modality to modulate performance on cognitive tasks. Previous work has tested the effect of tDCS on specific facets of cognition and executive processing. However, no randomized, double-blind, sham-controlled study has looked at the effects of tDCS on a comprehensive battery of cognitive processes. The objective of this study was to test if tDCS had an effect on performance on a comprehensive assay of cognitive processes, a standardized intelligence quotient (IQ) test. The study consisted of two substudies and followed a double-blind, between-subjects, sham-controlled design. In total, 41 healthy adult participants completed the Wechsler Adult Intelligence Scale, Fourth Edition (WAIS-IV) as a baseline measure. At least one week later, participants in substudy 1 received either bilateral tDCS (anodes over both F4 and F3, cathode over Cz, 2 mA at each anode for 20 min) or active sham tDCS (2 mA for 40 s), and participants in substudy 2 received either right or left tDCS (anode over either F4 or F3, cathode over Cz, 2 mA for 20 min). In both studies, the WAIS-IV was immediately administered following stimulation to assess for performance differences induced by bilateral and unilateral tDCS. Compared to sham stimulation, right, left, and bilateral tDCS reduced improvement between sessions on Full Scale IQ and the Perceptual Reasoning Index. This demonstration that frontal tDCS selectively degraded improvement on specific metrics of the WAIS-IV raises important questions about the often proposed role of tDCS in cognitive enhancement.”

The study design seems strong and suggests that one should think twice before running electric currents through the brain.


tDCS, reason to reserve judgement

6 May

Many of the articles I read on transcranial direct current stimulation follow a similar pattern. The intrepid reporter is strapped with electrodes to the skull and, after reporting a tingling feeling, describes some cognitive benefit from the procedure.

A good piece by Kira Peikoff in The New York Times breaks that pattern and acknowledges the limits of our knowledge about tDCS:

“In January, the journal Brain Stimulation published the largest meta-analysis of tDCS to date. After examining every finding replicated by at least two research groups, leading to 59 analyses, the authors reported that one session of tDCS failed to show any significant benefit for users.”



Transcranial direct current stimulation;

4 Sep

The research on transcranial direct current stimulation of the brain is fascinating. Given how easy it is to build the necessary equipment, there is a great temptation for self-experimentation. But caution is in order.

Here is a piece from the BBC on potential dangers:


“An active forum on reddit is devoted to the technology, and people there have complained of “burning to the scalp”. Another user wrote that they “seemed to be getting angry frequently” after using TDCS.”


TMS_Coimbra (5)

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