Data from a pilot study of Vagus Nerve Stimulation (VNS) Therapy treating Alzheimer’s disease (AD) has been published in the November issue of the Journal of Clinical Psychiatry. The article, entitled “Cognition-Enhancing Effect of Vagus Nerve Stimulation in Patients with Alzheimer’s disease: A Pilot Study” suggests that VNS Therapy may improve cognition in patients with AD.
In this study ten patients with mild to moderate AD were implanted with the VNS Therapy system and stimulated with left cervical (neck area) vagus nerve stimulation in the same way the treatment is currently delivered to treat patients with pharmacoresistant epilepsy. Response was defined as an improvement in or no worsening of AD symptoms based on the Alzheimer’s disease Assessment Scale-cognitive (ADAS-cog). Patients with AD typically worsen nine points in the ADAS-cog each year.
After three months of VNS Therapy, seven of ten patients with AD responded to VNS Therapy according to the ADAS-cog. Of the seven responders, six had improvements in their cognitive symptoms of AD and one had no worsening. The median change on the ADAS-cog was a 3 point improvement. After six months of VNS Therapy, seven of the ten patients had improvements in symptoms compared with their baseline ADAS-cog assessments. The ten patients had a median improvement in the ADAS-cog of 2.5 points after six months of VNS Therapy. VNS Therapy was well tolerated in all of the patients involved in the study, and the side effects were mild and transient.
“The results of this pilot study demonstrate a positive effect of VNS Therapy on cognition in patients with Alzheimer’s disease and merits further investigation in larger populations of Alzheimer’s disease patients,” said Magnus Sjogren, M.D., lead author of the article and Associate Professor at the department of Neuropsychiatry in Molndal, Sweden. “Of the seven patients showing improvement after six months with VNS Therapy, three were on concomitant cholinesterase inhibitors and four were not. The results also suggest that VNS Therapy may be a valuable and effective adjunctive therapy for patients already receiving drug therapy, as well as for those patients who do not tolerate cholinergic therapy.”
The standard of care for treating the cognitive effects of AD is a class of drugs known as cholinesterase inhibitors. According to the Alzheimer’s Association, about half of the people who receive cholinergic therapy experience a modest improvement in cognitive symptoms. Of the seven patients treated with VNS Therapy who showed improvements in cognitive symptoms at six months, three were receiving concomitant cholinesterase inhibitors and four were not. The patients receiving concomitant cholinesterase inhibitors during the study were taking those medications for at least one year prior to study entry. Importantly, the pilot results suggest that VNS Therapy may be beneficial in treating cognitive symptoms of AD with or without concomitant cholinergic therapy.