There is some evidence that certain toxins may increase the risk of acquiring dementia with heavy stress increasing the severity. It is often associated with several developmental disabilities, particularly Down syndrome.
Personality changes are common such as paranoia, indifference, hostility and aggressiveness.
Motor functions are generally good and persons have little trouble carrying out the routines of daily life in the early stages. In the advanced stages of dementia persons lose much of their intellectual ability. They can no longer reason and they fail to recognize family and even themselves. They require constant supervision and are unable to carry out the routines of life. In severe cases, language is often bizarre and meaningless.