From the New York Times:
Patronizing and negative language directed toward elderly people can lead to negative health consequences, researchers are finding.
In studies by Yale researchers, older people exposed to negative images of aging, including words like “forgetful” and “feeble,” performed worse on memory tasks and showed higher levels of stress. In another study by researchers from the University of Kansas, patients with dementia were more aggressive and less cooperative when health care workers addressed them with language like “good girl,” “dear” and “sweetie.”
The Kansas researchers concluded that “elderspeak” sends a message to older people that they are incompetent, which begins a cascade of negative effects including decreased self-esteem, depression, withdrawal and dependent behaviors.