Research has increasingly focused on the role of amyloid-β in Alzheimer’s disease (AD). A 2008 paper by SHANKAR,G.M. et al. in Night. With. 14,837-842,detailed how they “moved beyond cellular and animal models to isolate pathogenic forms of amyloid-β directly from human brains and apply them to reproduce key features of AD: synaptic dysfunction,loss of dendritic spines,and impaired memory per se.” The study identified “stable dimers of amyloid-β in Alzheimer’s cerebral cortex” and their impact on synaptic plasticity.

The research team isolated these dimers from other amyloid-β assemblies found in AD brain extracts. This allowed them to directly link synaptic deficits to these “smallest building blocks of oligomers and fibrils.”

Impact on Memory and Learning

“stable dimers of amyloid-β in Alzheimer’s cerebral cortex and their dose-dependent impairment of synaptic plasticity.”

Further experiments explored the impact of these dimers on cognitive function. “Perhaps most relevant to the human condition, we found that microinjection of dimer-rich isolates from the brains of deceased patients into the cerebral ventricles of healthy adult rats decreased the animals’ ability to remember a learned behavior (a passive avoidance task).” The researchers noted that “the timing of this amyloid-β-induced failure of recall mirrored the known temporal pattern of transcriptional regulation of synapse remodeling that accompanies such learning.”