Lately, we were researching about electrical stimulation of the hippocampus. Some experts said that it causes temporary amnesia – Zapping Memories Away.
It all started when Toronto experimental treatment centers started using deep brain stimulation (DBS) to improve memory in people with Alzheimer’s disease. Progressive loss of memory is the main symptom of this disorder, and while some drugs are available, they provide partial relief or even less than that.
But recently lucky a chance discovery by the same Toronto group shown us new direction. In 2008, they reported that stimulation of the hypothalamus caused vivid memory recollections for a 40-year-old man. In that case, the effect was entirely unintended and unexpected. The patient was being given DBS to try to curb his appetite (he weighed 350 pounds.)
And though the hypothalamus is involved in regulating appetite, not memory – but the fornix, a nerve bundle that passes through that area, is. It’s the main “nerve highway” connecting the hippocampus to the rest of the brain, and the hippocampus is vital for memory.
So following this new study they implanted electrodes to stimulate the fornix for 6 patients with moderate (early-stage) Alzheimer syndrome. What happened?
The results were as un[predictive as the whole thing. On average, the patients symptoms got worse over the course of the year. Alzheimer’s is a progressive degenerative disease, so this is what you’d expect to happen without treatment.
The authors say that the decline was a bit slower than you’d expect for these kinds of patients, but to be fair, as there was no control group for that research, results are hard to systemize.
Nevertheless, few patients did show memory improvements. These were the same two who reported memory recollections when the electrodes were first implanted (similarly to a research with 350-pound patient, for whom DBS was used against obesity):
Two of the 6 patients reported stimulation induced experiential phenomena. Patient 2 reported having a recollection of being in her kitchen few years ago… Patient 4 reported having the memory of fishing on a boat on a lake with his sons and catching a large green and white fish. On later questioning in both patients, these events were autobiographical, had actually occurred in the past, and were accurately reported according to their relatives.
Also, the stimulation caused brain activation, generally switching “on” the areas that are turned “off” in Alzheimer’s, and this lasted for a year (the length of the study so far). And there were no major side-effects.
All in all, these results are quite interesting, but we don’t know how well the treatment really works, and we won’t know until someone does a randomized controlled trial with a longer follow-up period; something which is, unfortunately, true of a lot of the latest DBS studies.