How a blood transfusion may one day recharge your brain

Humans are living longer and an increased lifespan has resulted in an elevated percentage of the population suffering from aged-related cognitive impairments such as Alzheimer’s disease.  Recent studies of animal models of aging provide insight into the mechanisms of brain aging as well as exciting new potentials to treat the age-related cognitive declines.  Tony Wyss-Coray and his colleagues at Stanford University compared older mice’s performance on standard laboratory tests of spatial memory after these mice had received infusions of plasma from young versus old mice, or no plasma at all.  Systemic administration of young blood plasma into aged mice improved age-related cognitive impairments in both contextual fear conditioning and spatial learning and memory.  Moreover, the researchers identified molecular and structural changes in the brains of older mice receiving infusions of young mice plasma.  

Wyss-Coray’s group identified changes in the hippocampus, a structure key for forming certain types of memories, notably the recollection and recognition of spatial patterns.  Both experience and aging modulate hippocampal activity and anatomy; veteran London cabdrivers have a larger than average hippocampus while normal aging deteriorates the hippocampus. In Alzheimer’s disease, this hippocampal deterioration is accelerated, leading to an inability to form new memories.  When researchers compared hippocampi from old mice who received the young mice plasma with those from old mice that had received plasma from other old mice, they found consistent differences in a number of biochemical, anatomical and electrophysiological measures known to be important to nerve-cell circuits’ encoding of new experiences for retention in the cerebral cortex.  It is unclear what factors present in the blood from young mice caused these changes or if similar results will occur in humans.  However, in the future these results may mean new therapeutic approaches for treating Alzheimer’s disease and other aged-associated cognitive disorders.