Which of the following is a NORMAL physiological change associated with aging?

NORMAL PHYSIOLOGICAL CHANGES WITH AGING: RENAL: GFR decreases approximately 1% per year after age 40; reduced creatinine clearance means medications eliminated renally accumulate to higher levels at the same dose — dosage adjustments are often required; MUSCULOSKELETAL: Muscle mass decreases (sarcopenia); bone density decreases; height decreases; CARDIOVASCULAR: Maximum heart rate decreases; cardiac reserve decreases; blood pressure often increases (not decreases) with age due to arterial stiffness; RESPIRATORY: Vital capacity decreases; chest wall compliance decreases; SENSORY: Visual acuity decreases; hearing loss (presbycusis); taste and smell decline; GI: Decreased GI motility (constipation risk); decreased gastric acid; NEUROLOGICAL: Slowed reaction time; decreased balance; memory retrieval (not storage) slows. Normal aging changes ≠ disease — these are expected, not pathological.