The impact of age on cognition

Do brain cells die as we age?
In a healthy brain, brain cells change shape over time, however there is limited actual cell (neuronal) death. Up to 10% is considered a normal part of ageing. Symptomatic dementia occurs when there is a 40% or more loss of neuronal connections in the brain.

What happens when our brain cells (neurons) change shape?
As we age, our neurons undergo structural changes that leads to less efficient connectivity and information processing. Consequently, gradual cognitive changes result as part of normal ageing, like struggling to multitask and hear and understand speech in background noise.
In Alzheimer's disease, brain cells (neurons) change shape in a different way to healthy ageing and by a different process that eventually leads to neuronal atrophy (cell death).

The impact of age on cognition, Murman. D (2015)