Etiology of Alzheimer's disease is not clear enough. It is believed that mutation of some genes (presenmilin-1 and presenilin-2) cause accumulation of beta-amiloid outside the neurons and tau protein inside the neurons that destroy them.
There is so called early-onset Alzheimer's disease that occurs before 60. Most of the cases are after 60.
Sex is not a risk factor for developing Alzheimer's disease.
There is no food that increases the risk for Alzheimer's disease. It is believed that some types of food like fruit and vegetables, bread, wheat and other cereals, olive oil, fish, and red wine, may, reduce the risk and course of Alzheimer's disease but there are no strong medical evidences about this.
Overweight is not a risk factor for getting Alzheimer's disease.
Stress and other traumas are probably not a risk factors for developing Alzheimer's disease.