Brain stimulation may boost cognitive function in people with Alzheimer’s disease

Twice daily transcranial direct current stimulation (tDCS) may boost cognitive function in people with Alzheimer’s disease, according to new research published in General Psychiatry. 

tDCS is a non-invasive brain stimulation method, with typically uses two electrodes placed on the patient’s scalp above the prefrontal cortex.

The technology delivers a constant low intensity electrical current, which may be able to ‘rewire’ the brain through the formation of neural networks.

Currently, tDCS is used to treat major depressive disorders, but the researchers wanted to find out if tDCS improves cognitive function in people with Alzheimer’s disease, and whether this was linked to recovering some level of cortical plasticity.

Participants all had mild to moderate Alzheimer’s disease

Around 140 patients over the age of 65 with mild to moderate Alzheimer’s disease were included in the trial. All participants had the disease for more than six months and scored below 26 on the Mini-Mental State Exam (MMSE).

The participants were randomly assigned to the treatment group or the control group. Participants in the treatment group received two daily sessions of active (constant low intensity 1-2 mA current) tDCS for five days of the week up for a maximum of six weeks, while the control arm received a fake version of the treatment.

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

Changes in neural plasticity were measured through the motor pathways of the nervous system, known as motor evoked potential or MEP.

Cortical plasticity improvement may be linked with improved cognitive function

In total, 133 patients completed the two-week intervention and 124 completed the six-week intervention.

At two weeks, patients in the treatment group had significantly improved the cognitive function compared to baseline, particularly their word recall, recall of test instructions, and word recognition. No changes were seen in the control arm.

The results also showed that patients in the treatment group had improved cortical plasticity at six weeks compared to basline.

With cognitive function improving and cortical plasticity improving in the treatment group, the researchers say the improvement in cortical plasticity may reflect the degree of cognitive improvement.

tDCS treatment is a significant and promising intervention

However, the researchers acknowledge some limitations to the study, including the small sample 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.

Even so, they conclude that the findings “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,” they added.

Lauren Nicolle

Lauren is a qualified journalist who writes primarily across the health and social care sectors. She is passionate about exposing the injustices faced by people with a learning disability, with a particular focus on equal access to healthcare.

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