The technique used is called deep brain stimulation, and is already used to treat the tremors and movement problems of some people with severe Parkinson’s disease. As well as having wires surgically inserted into the brain, recipients also get a power supply for the wires implanted under the skin near their collar bones.
Depending on the current, the wires can either boost activity in nearby brain cells or reduce it. In Parkinson’s disease, they are used to turn down the excessive firing of discrete clusters of nerve cells that control movement.
Alzheimer’s disease, however, is a less obvious target for such a treatment, because what causes this form of dementia is unknown. There has already been a small trial of brain stimulation using wires inserted into the brain’s memory centres, but this failed to help people with the condition.
Douglas Scharre of The Ohio State University Wexner Medical Center wanted to target another aspect of Alzheimer’s - the loss of problem-solving and decision-making abilities. “In Alzheimer’s disease, everyone thinks about memory, but if patients can figure out how to do things like get their lunch ready, or know they put their socks on before their shoes, that could really help care-givers.”
His team aimed to stimulate a bundle of nerve fibres called the ventral capsule/ventral striatum, which goes from the front part of the brain that is involved in problem solving through to deeper regions.
They put the wires into three people with early-stage Alzheimer’s, who began the study with a score of 4 or 5 on a symptom rating scale going from 0 to 18. Over about two years their score rose by up to three points, showing their condition had got slightly worse. By comparison, another 96 Alzheimer’s patients who were at a similar age and stage of the disease rose by up to six points.
One person in the trial even regained the ability to make simple meals, says her husband, despite the rise in her overall severity score. “That’s fairly rare,” says Scharre. “Usually if you lose an ability you don’t go back to it.”
But such improvements may not have been real, or caused by the treatment, because the trial was not randomised or blinded. For example, doctors could have unintentionally picked people for surgery who seemed likely to decline more slowly, or people receiving the implants could have improved thanks to the placebo effect. “It’s too soon to get any hopes up yet,” says Carol Routledge of Alzheimer’s Research UK.
Another reason for caution is that when brain stimulation was first tried in Alzheimer’s, on the brain’s memory centres, a small trial initially suggested it worked – only for a larger trial to disappoint.