Résumé
AbstractBackground: Sophisticated and expensive biomarkers are proposed for the diagnostic of Alzheimer disease (AD). Amyloid process seems to be early in AD and brain amyloid load affects the frontal lobe. Our objective is to determine if certain simple clinical signs especially frontal-related signs could help reach an earlier and better diagnosis. Methods: In the frame of the 3-City cohort, we conducted a nested case-control study comparing incident cases of Alzheimer’s dementia to controls matched for age, sex and education. The standardized neurological exam included extrapyramidal signs (akinesia, rigidity, rest tremor), pyramidal symptoms (spastic rigidity, Babinski reflex), primitive reflexes (snout, palmomental reflex grasping) and tremor (essential, intentional, head) at the time of diagnosis and two years before. Results: We compared 106 incident Alzheimer’s dementia subjects (mean age at diagnosis 82.2 (SD=5.9); median MMSE at diagnosis=23) to 208 matched controls. In patients younger than 80, palmomental reflexes were more frequent in Alzheimer’s dementia than controls, two years before diagnosis (25.0 vs. 7.0%, p=0.03) and at time of diagnosis (30.3 vs. 12.3%, p=0.02). No difference was observed for other signs two years before diagnosis or for patients older than 80. Conclusions: Before diagnosis, the clinical examination of AD patients is not strictly normal, the primitive reflexes appear to be pathological. It might be in connection with the frontal amyloid load at an early stage of the disease. Clinical examination can reveal simple and interesting signs that deserve consideration as the other more invasive and expensive biomarkers.