A 20 year old blind man who can remember every day of his life since the age of 11 is adding new weight to the theory that deep brain stimulation may offer hope for future treatments of Alzheimer’s disease. The man, known only as HK and from the Nashville area, has what is known as ‘hyperthymesia’.
The term hyperthymesia derives from the Greek words thymesis, meaning "remembering" and hyper meaning “excessive”. His brain scan when compared to people of similar age matched controls shows that there are number of differences in his brain structure. His brain is smaller than average, something scientists think is due to his premature birth. His amygdala is 20% larger than average and the connectivity between this part of the brain, the hippocampus and other regions of his brain, is much more extensive.
The amygdala and hippocampus are important brain structures. The amygdala is involved in many of our emotions and motivations, particularly those relating to survival. The hippocampus has an important role in organizing and storing memories. Knowing this, and extrapolating from their discoveries of HK’s brain, it is at least possible to appreciate why scientists hope this knowledge can then be applied to Alzheimer research and treatment. Scientists now believe that deep brain stimulation to key areas of the brain may offer hope in the future to people with memory disordered illnesses and conditions such as Alzheimer’s.
HK is only the second person "ever documented in scientific literature", although there are more cases of hyperthymesia reported. This Health Central video is great way to understand more about how memories are formed, how complex the brain is, and how much more we need to know about it.
Current research into deep brain stimulation, using small numbers of people with Alzheimer’s, is beginning to examine its efficacy. Electrical impulses to specific regions of the brain that have a role in memory already show that neuron activity increases. Neurons are cells that process and transmit information by electrical and chemical signalling.
Published in the Archives of Neurology, the study reports on the physical changes in the brain using PET (Positron Emission Tomography) brain scans
after deep brain stimulation and notes there was a greater effect in people with less cognitive damage.
Because research is in its earliest phases the research focus was more on issues of safety rather than an evaluation of patient improvement. A lot more research needs to be undertaken before we will know for sure if deep brain stimulation can offer any real hope as a treatment for Alzheimer’s and who might benefit the most.
For more information see Carol’s sharepost on FDA approval for more research into deep brain stimulation.
Ally, B., Hussey, E., and Donahue, M. (2012). A case of hyperthymesia: rethinking the role of the amygdala in autobiographical memory. Neurocase, 1-16 DOI: 10.1080/13554794.2011.654225