For the Cortex, Neuron Loss May Be Less Than Thought

Just a decade ago, almost all neuroscientists thought the brain inexorably loses neurons with age, ultimately leading to serious cognitive difficulties. But there is growing evidence that in normal brains (as opposed to those of people with Alzheimer's disease), the neocortex, the brain area governing much of human cognition, may not experience large neuronal losses. Instead, the cognitive declines that occur with normal aging may be due to more subtle changes, such as loss of myelin and decreases in either neurotransmitters or their receptors. Not everyone accepts the idea that cortical neurons are maintained, but if it is correct it may open the door to the development of drugs to improve cognitive functioning in the aged.