Primitive reflexes and dementia: results from the Canadian Study of Health and Aging.

We report on the prevalence of primitive reflexes (PR) and their association with cognitive, behavioural, functional and clinical characteristics in 2914 Canadians 65 years and older. Data were collected as part of the Canadian Study of Health and Aging (1990-92) and included individuals living in the community and in institutions. PR were more commonly found in demented subjects. Demented subjects with prehensile PR (i.e. grasp, traction, suck) had significantly more functional and behavioural problems and were more severely demented. The presence of any PR increased the likelihood of other neurological findings (e.g. bradykinesia). Vascular dementia (VD) cases were more likely to have unilateral primitive PR than probable Alzheimer's disease (Pro AD) and Parkinson's dementia (PD) cases. PD cases were more likely to have glabellar and traction responses. While more common among the demented, PR lacked sufficient sensitivity to be an early diagnostic tool for dementia. Prehensile PR may help to define particular types or severity of dementia.