PRESUMABLY AS PLAQUE FORMATION IN THEIR BRAINS ACCELERATED. IN PEOPLE WITHOUT THE GENETIC PREDISPOSITION, PROTEIN LEVELS IN THE SPINAL FLUID ROSE UNTIL AGE 50, THEN BEGAN DECLINING SLOWLY. NO DIRECT CONNECTION WAS FOUND BETWEEN LEVELS OF THE PROTEIN AND ALZHEIMER'S SYMPTOMS, BUT THE MENTAL DECLINE FROM ALZHEIMER'S IS THOUGHT TO PROGRESS ONLY AFTER YEARS OF PLAQUE BUILDUP AND USUALLY BECOMES EVIDENT IN OLD AGE, THE STUDY SAID. "THESE FINDINGS HAVE IMPLICATIONS FOR THE PRECLINICAL DIAGNOSIS OF ALZHEIMER'S DISEASE, AS WELL AS FOR TREATMENT," SAID STUDY AUTHOR ELAINE PESKIND OF VA PUGET SOUND HEALTH CARE SYSTEM AND UNIVERSITY OF WASHINGTON SCHOOL OF MEDICINE, SEATTLE. "THERAPEUTIC STRATEGIES AIMED AT PREVENTION OF ALZHEIMER'S DISEASE MAY NEED TO BE APPLIED IN EARLY MIDLIFE OR EVEN YOUNGER AGES TO HAVE MAXIMAL EFFECT ON AMYLOID (PLAQUE) DEPOSITION," SHE ADDED.