Alzheimer's disease: How daily electrical stimulation may help

• Researchers say that electrical stimulation delivered twice daily may boost cognitive function in people with Alzheimer’s disease.
• They say the low electrical current can help the brain form new neural networks.
• The study sample was relatively small, meaning more research is necessary.

A new study is reporting that electrical stimulation may help boost cognitive function in people with Alzheimer’s disease.

Specifically, researchers say that twice daily non-invasive electrical stimulation can help fire up the brain’s plasticity through new neural networks.

The results of their small clinical trial were published today in the journal General Psychiatry.

The technology, known as transcranial direct current stimulation, or tDCS for short, can help enable the brain to “rewire” through the formation of new neural networks, the researchers said.

The electricity comes from a device with two electrodes, placed over specific areas of a person’s head, delivering a constant flow of low-intensity electrical current.

The study authors point out it’s a method more practitioners are using in many areas of medicine, including treating depression.

How the brain electric stimulation study was conducted

The scientists looked at 140 people from four hospitals who had mild to moderate Alzheimer’s disease.

The subjects were randomly allocated to receive either two daily sessions of active (constant low intensity 1-2 mA current) or fake tDCS for five consecutive days of the week for six weeks.

The goal was to ascertain whether tDCS could improve cognitive function in people with Alzheimer’s disease and, if so, whether it could lead to them recovering some level of cortical plasticity (the brain’s capacity to form new neural networks).

The tDCS was applied to subjects’ prefrontal cortex, the part of the brain involved in higher order activities, such as working memory, decision-making, planning, moderating social behaviors, and certain aspects of speech and language.

Subjects were over the age of 65, had Alzheimer’s for more than 6 months and did not score above 26 on the Mini-Mental State Exam (MMSE). A score of 24 is generally considered indicative of cognitive impairment.

The groups who received tDCS and those who didn’t were comparable in terms of gender, age, and education.

Researchers used MMSE and the Alzheimer’s Disease Assessment Scale-Cognitive (ADAS-Cog) Test, which focuses on language and memory, to evaluate cognitive performance at the beginning of the trial, after two weeks, and again after six weeks.

Changes in neural plasticity were measured in readings of electrical signaling through the motor pathways of the nervous system, known as motor evoked potential (MEP).

How electrical stimulation can help with Alzheimer’s

Researchers said 133 people completed the two-week intervention and 124 completed the six-week intervention. Their reasons for withdrawal varied, but no one dropped out because of discomfort.

The researchers reported that “compared to baseline, 30 daily 20-minute sessions of tDCS significantly improved the cognitive function of those in the tCDS group, particularly in word recall, recall of test instructions, and word recognition. The sham group showed no such improvements.”

The researchers added that cortical plasticity was impaired in people with Alzheimer’s, but it improved after six weeks of tDCS.

Along with a decrease in MEP, word recognition and word recall improved in the tDCS group, but not in the other group. Researchers said this improvement in cortical plasticity may reflect the degree of cognitive improvement.

“The results of this study strongly indicate that tDCS treatment is a significant and promising intervention for improving cognitive function in (Alzheimer’s disease). In addition, plasticity plays a vital role in cognitive change,” the researchers wrote.

They added it’s still not clear how tDCS might exert some effects, citing previous research, indicating the technology may alter ion activity, neurotransmitter release, and electrical activity in various brain areas.

Researchers also acknowledged limitations to their findings, including the small study size, the lack of MRI or electroencephalography scans to chart changes in brain structure, and the absence of blood samples and cerebrospinal fluid to monitor neurotransmitter changes.

Experts react to Alzheimer’s treatment study

Dr. Eric Chaghouri is a psychiatrist and medical director of Lucid Wellness Center in Los Angeles, where he works with Alzheimer’s patients using transcranial magnetic stimulation (TMS) therapy – a non-invasive brain stimulation for cognitive improvement.

“I think what makes this innovative and unique in its sense is that they are using cortical plasticity as a biomarker of treatment effect, rather than using brain imaging of AD (e.g. MRI and a head CT),” Chaghouri, who was not involved in the study, told Medical News Today.

Dr. Jean-Philippe Langevin, a neurosurgeon and director of Restorative Neurosurgery and Deep Brain Stimulation Program at Pacific Neuroscience Institute in California who also was not involved in the study, told Medical News Today the application of tDCS to treat Alzheimer disease isn’t a novel idea, but the more research done to confirm it, the better.

“The electrical stimulation emulates normal physiological activity and promotes the creation of new connections between brain cells,” Langevin said. “In the case of Alzheimer for example, the extent of the deficits is often in excess to the degree of brain tissue lost. This means that we have an opportunity to regain some function by promoting the restoration of connections within the brain cells that are still functioning.”

He added that tDCS is safe, non-invasive, and the risk of side effects are low at the level it was used in the study.

“The primary use of tDCS is as an adjunct for the treatment of depression,” Langevin said. “Other applications have included anxiety disorder, pain disorder and neurorehabilitation after TBI or stroke.”

Dr. Paul Schulz, a professor and director of the Neurocognitive Disorders Center at UTHealth Houston who was not involved in the study, told Medical News Today the research is important because of its success.

“The brain uses electricity for one brain cell to talk to another,” Schulz said. “When the stimulation crosses a certain threshold, it induces long lasting changes in the connection between brain cells that we believe underlie how we remember things.

“An analogy would be if we see clouds in the sky and then it rains, that double stimulation leads to crossing a threshold that changes brain connections such that the next time we see clouds, we think that it might rain,” he explained.

Using electrical currents as treatment

Schulz said over the years, many people have tried applying currents to the brain to help “cross that threshold” to aid in the formation of memories.

He said trial and error may have struck upon the correct factors such as which areas to stimulate and how much and what type of current.

“We have been learning a lot about what works and what doesn’t,” Schulz said. “One important fact is that the brain with early Alzheimer’s isn’t the same as a normal one. So, where we stimulate may have to change according to what pathways are working and what pathways may not be connected any more.”

“This group chose to stimulate our attention area in the frontal lobe,” he explained. “That is a good idea because attention is the first step in memory, word finding, etc. And it appears to be the most amenable area to plasticity. So, it resulted in a positive finding here.”

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