Electrical stimulation of the brain can be used to improve mental processes in Alzheimer’s patients, according to a new study.
Researchers found that twice-daily current stimulation sessions of around 20 minutes improved the memory and overall cognitive performance of elderly people living with the condition.
The innovative technology, known as transcranial direct current stimulation (tDCS), could also be used as a treatment to improve brain plasticity in Alzheimer’s sufferers – enabling ‘rewiring’ through the formation of new neural networks.
The study, published in the journal General Psychiatry, sought to discover whether electrical stimulation might improve cognitive function in people living with Alzheimer’s – a progressive condition that causes confusion and difficulties in memory.
The tDCS technology is delivered via a device with two electrodes placed over specific areas of a person’s head, which transmits a constant, low-intensity electrical current.
It’s already beginning to be used across many areas of medicine, including for the treatment of depression.
The researchers, from China, recruited 140 patients from four different hospitals with mild to moderate Alzheimer’s and randomly allocated whether they would receive the two daily sessions of the active, constant low intensity 1-2 mA current, or a ‘sham’ version of the tDCS in a control or placebo group.
Each participant received their respective treatment five days a week, over a maximum period of six weeks.
All participants were over the age of 65 and had had the disease for more than six months, with all also having scored below 26 on the Mini-Mental State Exam (MMSE), in which a score of less than 24 is seen as abnormal and indicative of cognitive impairment.
Both the tDCS group and the control group were comparable in terms of age, sex, and educational attainment.
The currents were applied to the prefrontal cortex – the region of the brain involved in higher-order activities such as planning, decision-making, working memory, moderating social behaviours and controlling aspects of speech and language.
The researchers then used the MMSE and the Alzheimer’s Disease Assessment Scale-Cognitive (ADAS-Cog) Test, which focuses on language and memory, to evaluate cognitive performance at the start of the trial, after two weeks, and again after six weeks.
Readings of electrical signalling through the motor pathways of the nervous system – known as motor evoked potential or MEP – were also used to indicate changes in neural plasticity, which refers to the capacity of the nervous system to modify itself in response to experience and injury.
A total of 133 patients completed the two-week intervention and 124 completed the six-week intervention, with no participants withdrawing due to discomfort.
The results of the study showed that after two weeks, tDCS significantly improved the cognitive function of those who received the treatment, particularly their word recall, recall of test instructions and word recognition.
No such improvements were noticed in the group receiving the ‘sham’ treatment.
The results also showed that though cortical plasticity is impaired in those with Alzheimer’s, this improved in patients after six weeks of tDCS.
As well as a decrease in MEP, word recall and word recognition also improved in those in the tDCS group but not among those in the placebo group, suggesting that the improvement in cortical plasticity may reflect the degree of cognitive improvement.
First author Xingxing Liu, from the Zhejiang University in China, said the results were positive to suggest a treatment for those suffering from Alzheimer’s.
“Taken together, tDCS is a promising method for improving cognitive function with sufficient treatment,” Liu said.
“It is supported by electrophysiological evidence (MEP) in patients with Alzheimer’s disease, and these results support the potential role of cortical plasticity as a biomarker of treatment effect in patients with Alzheimer’s.
“tDCS can significantly improve the working memory of older patients, and the stimulation changes the resting-state functional connectivity of the frontoparietal brain region.
“The results of this study strongly indicate that tDCS treatment is a significant and promising intervention for improving cognitive function in Alzheimer’s.
“In addition, plasticity plays a vital role in cognitive change.”
However, despite the positive results of their study, the researchers did admit to limitations such as the small study size, the lack of MRI or electroencephalography scans to chart changes in brain structure and the absence of cerebrospinal fluid and blood samples to monitor neurotransmitter changes.
