twenty minutes of brain stimulation over several days can dramatically improve memory for words in adults over 65 years old. if true, this sort of result would be amazing scientifically & practically. that's a big if.  

original article: Grover et al., 2022 (Nature Neuroscience), reported in: The Independent by Nina Massey on 22nd August 2022

this story was in episode 30 #brainstim #tacs #memory #learning #aging

the error bar says

the Independent reports that four days of brain stimulation can dramatically improve memory for words in older adults & the effects last for a month.

in a large & quite intensive study, a total of 150 adults aged 65 or over were asked to listen to lists of 20 words read aloud, then to repeat all those they could remember in the two minutes after the end of the list. they did this 5 times each day for 6 days. for all of the approximately 20 minutes that this took, they received electrical brain stimulation, of different kinds over one of two brain areas.

in the first experiment, a group of 20 adults had a high-frequency stimulation over the prefrontal cortex - an important part of the brain involved in thinking. & other things. another group had low-frequency stimulation over the parietal cortex - an important part of the brain involved in thinking. & other things. a third group had a fake kind of stimulation.

over the five days, as well as one month later, the high frequency frontal group were much better at remembering the words at the beginning of the list, while the low frequency parietal group were much better at remembering words towards the end of the list.

a second experiment reversed the stimulation types & found no improvements in memory. a third experiment repeated the first one & found similar results.

can electricity improve memory?

probably not.

oh, dear listener, the error bar laments.

i don't know how to deal with this kind of science. i can find nothing obviously or importantly wrong here, in the experimental design, analysis, or presentation of the results. indeed, it is very good. but i just don't believe them. they are too good to be true. i am in the 'uncanny valley' where data looks so good & realistic that there just must be something wrong.

there are some problems - there always are - but the problems i found are not serious. i list them here, because that's what i do:

first, the hypotheses, design & analysis seems to be based on a single paper published in 2013. nothing wrong with that, but the force with which the paper is written suggests there's a much-stronger evidence base than a single paper.

second, the style of the paper is SO 1990s - every piece of evidence is 'crucial' & 'decisive', there are 'gold standards', 'confirmations', 'rulings-out' & 'overwhelming majorities' in place of simple numerical facts, doubts or failures. everything seems to work exactly as it should have.

third, the results consist mostly of relatively-specific comparisons between individual groups, conditions, or time-points. that's fine, but there's no explanation of why some specific comparisons are given rather than others - they all seem a little arbitrary or selective.

fourth, it just seems unlikely that one brain area would do one task & be affected only by one frequency of electrical stimulation, while another brain area does another task & is affected only by another frequency of stimulation. it's just too neat.

but really i had nothing of substance here... until i remembered that the error bar covered a similar report from the same group way back in episode 2. let's have a listen...

"if true, this result would be an enormous and very specific effect of brain stimulation on behaviour. and that's the only reason i have for not really believing it - it's just too strong to be true..."

exactly! just eighteen months ago, this same group of researchers published some very clear & strong results using a similar method but on a very different topic - obsessive compulsive disorder. how can a group of researchers switch topics so quickly yet find - again - extremely-large effects of a brain stimulation method that many other researchers find extremely difficult to get working at all?


impressively dubious


The Independent: fact - scientific story reported well