AGE
Greater chance of developing in older age, less common in kids and adults.
Genetics
Many diseases have strong ties to family history because of specific mutations that can inherit the disease, spontaneous mutation can also happen times the combination of both.
ENVIRONMENT
Exposure to pollution, chemicals, Drugs, and toxins, certain types of infections, and even where you live may all play role.
MEDICAL HISTORY
Some neurodegenerative conditions can either happen because of specific medical events or can get worse because of that.
Eg: cancer, certain infections, head injuries, etc
HABITS ROUTINE AND CHOICES
Include what you eat, how active you are, use of tobacco products, alcoholism, etc.