Alzheimer’s disease continues to be an elusive and worthy opponent for the medical community. A small and preliminary study examined eight people who lived into their 90s and who had excellent recall until they died. This, despite the fact that their brains had the amyloid plaques and tau tangles that defines Alzheimer’s. Other studies have come to similar conclusions with younger patients. This study, by researchers at Northwestern University Feinberg School of Medicine, stands out because the age of the participants would suggest that by 90 or older, amyloid plaques and tau tangles should have done their damage.
“What’s significant about these findings is that they show there can be high densities of plaques and tangles in the brains of some elderly individuals who are cognitively normal or even superior,” Changiz Geula, PhD, lead author of the study, tells STAT.
There are two theories about why people with “Alzheimer brains” don’t actually develop the disease. Cognitive reserves says that well-educated people who remain intellectually engaged won’t show the memory loss that comes with loss of synapses and neurons in the brain’s memory region. They’ve built up enough backup to allow them to sustain losses.
The other theory is that biochemical or genetic performance prevents cognitive decline “even when the brain is riddled with pathological amyloid and tau. For instance, some people might produce molecules that make amyloid nontoxic, in which case even if plaques build up they don’t destroy synapses.”