July 22, 2016 - A multicenter phase 2 study showed that some patients with mild Alzheimer's disease (AD) who received deep brain stimulation of the fornix (DBS-f) experienced an increase in cerebral glucose metabolism, and some patients experienced a slowing of cognitive decline.
These positive effects were seen only in patients aged 65 years and older, not in younger patients.
Nevertheless, the findings are encouraging, said lead researcher Andres Lozano, MD, PhD, professor and chairman, Department of Neurosurgery, University of Toronto, Canada.
"These findings indicate that we are headed in the right direction with our research on DBS as a treatment of Alzheimer's disease. In AD, certain areas of the brain shut down and no longer metabolize glucose to the normal level, and we hope that by stimulating the circuits in the brain that are involved, that we can restore function within the fornix and that that in turn will lead to improvement in the signs and symptoms of Alzheimer's," Dr Lozano told Medscape Medical News.
The study was published online July 18 in the Journal of Alzheimer's Disease.
Age a Predictor of Response?
Dr Lozano and his group conducted an earlier phase 1 studyinvolving six patients with Alzheimer's disease. In that study, in some patients who received constant DBS to the fornix, which is a major fiber bundle in the brain's memory circuit, there was an increase in hippocampal volume after 1 year.
The current phase 2 study included 42 patients aged 45 to 85 years. Twelve patients were younger than 65 years; 30 were 65 years of age or older.
The patients had mild dementia with global Clinical Dementia Rating (CDR) scale scores of 0.5 or 1 and Alzheimer's Disease Assessment Scale–11 (ADAS-Cog 11) scores of 12 to 24 at baseline.
All patients were taking stable doses of donepezil (Aricept, Eisai Inc), galantamine (Razadyne, Janssen Pharmaceuticals, Inc), or rivastigmine (Exelon, Novartis Pharmaceutical Corporation) for at least 2 months prior to the start of the study.
The patients were implanted with DBS electrodes directed at the fornix. They were then were randomly assigned to receive either active or sham stimulation and were monitored for 12 months. Once follow-up was complete, the electrodes were turned on for all patients.
In addition to evaluating the safety of DBS-f, the investigators measured changes in cognitive function using the Alzheimer's Disease Assessment Scale–Cognitive Subscale (ADAS-Cog) and the Clinical Dementia Rating–Sum of Boxes (CDR-SB) scales at 6 and 12 months.
Secondary clinical outcomes at 6 and 12 months included the California Verbal Learning Test, Second Edition (CVLT-II), the Alzheimer's Disease Cooperative Study Activities of Daily Living scale (ACDS-ADL), and the Neuropsychiatric Inventory (NPI).
Changes in cerebral glucose metabolism were assessed with [18F]-2-deoxy-2-fluoro-D-glucose positron emission tomography (FDG-PET).
Overall, at 12 months, there was no significant difference between the patients who were receiving stimulation and those who were not. For both groups, changes in scores on the ADAS-Cog 13 and the CDR-SB were similar; both showed comparable declines. (segue...) Fonte: MedScape.
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