Deep brain stimulation (DBS) is a technique where wires are implanted into specific areas of the brain to deliver very mild electrical stimulation. Colloquially referred to as a "brain pacemaker," DBS is currently being investigated as treatment for a variety of conditions, from Parkinson's disease to depression. A new study from Ohio State University is now suggesting the technique could be effective in improving behavioral and cognitive deficits in patients suffering from Alzheimer's disease.
For some years, DBS has been an FDA-approved treatment for both Parkinson's disease and obsessive compulsive disorder. In clinical trials it's also showing promise for treating chronic pain, depression, addiction and even anorexia. Understandably, since the treatment involves a complex and invasive surgical procedure, it's not something physicians are immediately jumping to for most patients.
This new study from a team at The Ohio State University Wexner Medical Center set out to examine the impact of DBS on Alzheimer's disease, by specifically targeting frontal brain regions. This pilot Phase 1 study was incredibly small, with only three subjects, but researchers suggest the early results show promise for further investigations.
"Our study findings suggest that modulation of frontal lobe networks by DBS holds promise for improving connectivity, cognitive and functional performance, and should be further studied in Alzheimer's disease," says Ali Rezai, a neurosurgeon working on the current clinical trial.
Phase 1 clinical trials are ostensibly designed to demonstrate the safety of a given treatment, with proper efficacy determined in larger sample groups in subsequent trials. In this case, the DBS treatment was reportedly well tolerated, with no significant adverse effects. After a treatment period of at least 18 months all three subjects displayed less symptomatic decline relative to a matched comparison group not receiving the DBS.
Not everyone is convinced this is a useful or promising study, though, with some researchers suggesting the extremely small scale of the trial means that, while the process is most likely safe, the efficacy results are negligible. Professor Robert Howard from University College London is particularly critical of the study, pointing out there is no evidence that DBS improves, or even slows down, the actual neurological decline associated with Alzheimer's, so the perceived benefits found in this early study are probably placebo effects.
"Claimed benefits are most likely placebo effect," says Howard. "Before we can draw any conclusions about efficacy or usefulness of deep brain stimulation, randomized placebo-controlled trials need to be performed within which larger numbers of participants are randomly allocated to deep brain stimulation or placebo (most likely an implanted stimulator that isn't switched on or that stimulates at an ineffective frequency) and participants, their clinicians or trial assessors are unaware of individual treatment allocations,"
The Ohio State team's next step is to try to investigate whether non-surgical methods can be used to target those same brain areas, offering a less invasive model for further research. Generally, externally sourced brain stimulation, most commonly explored through transcranial magnetic stimulation, isn't as specifically targetable as surgically implanted electrodes.
Last year, a breakthrough technique was developed by an international team demonstrated an effective way to deliver a high-frequency electrical currents into a very small targeted area of the brain using small electrodes mounted on the scalp. This technique, which is still in early trial phases, could certainly help propel forward the kind of research that otherwise requires invasive surgical procedures to study.
The new study was published in the Journal of Alzheimer's Disease.
Source: Ohio State University
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