Alzheimer’s disease. Abstract collage artwork depicting the effects on perception, speech and memory, in a patient suffering from Alzheimer’s disease. Alzheimer’s is a progressive nervous disease, the most common cause of senile dementia. It is rare before age 60; up to 30% of people over age 85 are affected. Breakdown and loss of nerve cells and tissue in the brain occurs. Symptoms of Alzheimer’s disease fall into three broad stages: beginning with forgetfulness; this progresses to severe memory loss, disorientation, and inability to find the right words in speech; as anxiety increases, the personality changes from confusion to possible symptoms of psychosis and delusion.