Brain atrophy. Coloured magnetic resonance imaging (MRI) scan of a sagittal section through the brain of a 51 year old male, showing cerebral atrophy. Atrophy of parts of the cerebrum of the brain occurs in various disorders, including stroke, Alzheimer's disease, & AIDS dementia. The yellow/ green brain is sliced" through, showing the large folded cerebrum (at top). Here the area of the upper cerebrum affected by atrophy is coloured brown. Atrophy is shrinkage and wasting away of tissue. In stroke, brain cells die due to deprived blood supply to the brain; in Alzheimer's disease, the brain shrinks leading to senile dementia."