Failure of Immunotherapy in Alzheimer’s Clinical Trials May Be Due to Presence of Another Form of Dementia

Failure of Immunotherapy in Alzheimer’s Clinical Trials May Be Due to Presence of Another Form of Dementia
Immunotherapy for Alzheimer’s disease may not provide a clinical benefit in patients that also developed vascular cognitive impairment and dementia (VCID), another form of dementia, according to a new study. The study, “Reduced Efficacy of Anti-Aβ Immunotherapy in a Mouse Model of Amyloid Deposition and Vascular Cognitive Impairment Comorbidity,” was published in the Journal of Neuroscience. VCID is the second most common form of dementia behind Alzheimer's disease, and it is estimated that 40 percent of Alzheimer’s patients also have some form of VCID. The main hallmark of Alzheimer’s disease is the accumulation of aggregates of the Aβ protein (Aβ plaques), whose presence disturbs neuronal function and brain activity. For this reason, one promising technique for Alzheimer's, called anti-Aβ immunotherapy, consists of the administration of proteins that react against these aggregates, clearing them from the brain. “While successful in clearing Aβ and improving cognition in mice, anti-Aβ immunotherapy failed to reach primary cognitive outcomes in several different clinical trials,” the authors wrote. “We hypothesized that one potential reason the anti-Aβ immunotherapy clinical trials were unsuccessful was due to this high percentage of VCID comorbidity in the [Alzheimer's] population.” To test their hypothesis, researchers compared the effect of anti-Aβ immunotherapy in normal mice and mice with both Alzheimer’s and VCID. To do so, the scientists induced hyperhomocysteinemia (HHcy -- a form of VCID) through diet in mice with Alzheimer’s disease. After three months on the diet, when cerebrovascular pathology was in
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