Prevalence of Primitive Reflexes and Parkinsonian Signs in Dementia

Abstract

Primitive reflexes and parkinsonian signs are used by clinicians to differentiate among dementias. We reviewed our clinical sample to determine whether primitive reflexes were more prevalent in frontally-based dementias and whether parkinsonian signs were more common in dementia with Lewy bodies (DLB) than in other types of dementia. We retrospectively reviewed charts from 204 patients with dementia who presented for consultation at Baycrest's Ross Memory Clinic between April, 2003, to December, 2007. A greater proportion of subjects with DLB and dementia of the Alzheimer type with cardiovascular disease had primitive reflexes than subjects with frontotemporal dementia (FTD). Primitive reflexes were not positively predictive of FTD or vascular dementia (VaD). Dementia with Lewy bodies subjects were more likely to have parkinsonian signs than the other dementias, and bradykinesia and rigidity were positively predictive of FTD. The palmomental reflex was the most common primitive reflex in the sample, and cogwheeling was the most common parkinsonian sign. There was no significant difference between early- and late-stage groups in presence of primitive reflexes or parkinsonian signs. Primitive reflexes appear not to be clinically discriminative of frontally-based dementias such as FTD and VaD.