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Alzheimer’s disease is a degenerative condition that most commonly results in dementia, or memory loss. It affects an older population (generally those older than 65), and progressively gets worse until death since there is currently no effective treatment. Approximately 2% of 65 year olds have Alzheimer’s, and this percentage increases with increasing age (some statistics report up to 50% of 85 year olds have some form of the disease). In its most advanced stages, Alzheimer patients usually require a caregiver to assist them in activities necessary for everyday life.
The exact cause of Alzheimer’s is not known, but several theories exist regarding its pathology. Hypotheses argue a lessened presence of acetylcholine or faulty proteins cause Alzheimer’s. Although Alzheimer’s does not generally appear to be an inherited disease, several genes have been pin-pointed as potential risk factors for the disease. Regardless of its exact cause, Alzheimer’s results in disappearance of neurons within the memory centers of brain (generally the temporal and parietal lobes), thereby causing memory loss. This loss of neurons is coupled with increasing presence of beta-amyloid plaques and tangles within the Alzheimer’s patient’s brain.
Just recently, in January 2008, Canadian doctors initiated a study on the effects of DBS on six Alzheimer patients (With no FDA involvement because of the location). They realized the possible potential of DBS in preventing or even reversing the memory loss of Alzheimer’s when they accidentally elicited vivid, decades old memories in a patient whose obesity they were attempting to cure with DBS of the hypothalamus (believed to house the satiety center). The discovery was especially intriguing because the obese DBS patient consistently scored higher on a memory test when the stimulator’s electrodes were turned on as opposed to when they were off. If the results of this study prove DBS is an effective treatment option for Alzheimer’s patients, it would be quite a milestone in the treatment of the disease as there are currently no other truly effective treatments.
While there is no known effective treatment for Alzheimers, maintaining a healthy lifestyle and performing mental exercise is recommended to slow the memory loss associated with the disease. Several pharmaceuticals have been created and are sold to treat Alzheimer’s, none of which are particularly effective. Several, known as acetylcholinesterase inhibitors, are based on the theory that loss of acetylcholine causes Alzheimer’s, and therefore slow the degeneration of this neurotransmitter in the Alzheimer patient’s brain in an attempt to prevent their memory loss from getting worse. Various psychological techniques are also often used in conjunction with pharmaceuticals in an attempt to maintain memory through mental stimulation. Additionally, since so many people are affected by this disease and there is currently no cure, there are countless other treatment options currently being tested.
The use of acetylcholinesterase inhibitors is not particularly effective in reversing or stopping the progression of Alzheimer’s; rather, they attempt to slow the worsening of Alzheimer’s patients’ dementia. Like other pharmaceuticals, acetylcholinesterase inhibitors have a long list of side effects, including nausea, vomiting, muscle cramps, and bradychardia. Additionally, although there are no negative side effects of maintaining good overall mental and physical health, neither of these activities has much of an effect on the progression of Alzheimer’s. Therefore, DBS, if proven effective at stopping or even reversing the dementia in Alzheimer’s patients, it would be the first actual treatment for Alzheimers.
n the Canadian study, the memory-illiciting DBS was focused on the hypothalamus, but some scientists believe residual stimulation of the fornix caused the vivid memories. Although the Canadian patient was obese and did not have Alzheimer’s, doctors hope to prove DBS of the fornix is a good treatment option for Alzheimer’s with their current study involving 6 patients who have Alzheimer’s.
In the obese Canadian patient, high voltages put out by the stimulator caused unpleasant hot feelings and subsequent sweat excretion, along with occasional visual sensations of flashes of light. However, this could possibly be remedied with parameter adjustment and refinements in electrode placement.
The serendipitous discovery is reminiscent of experiments by neurosurgeon Wilder Penfield in the late 1960's in which superficial temporal lobe stimulation produced vivid, long-lost memories in a small percentage of patients. Since then, researchers have had trouble producing such an effect with any regularity. As the Canadian team expands their experiments to a greater number of subjects, time will tell if they can.
Toronto Western Hospital - Professor Andres Lozano, neurosurgery expert