Which of the following is NOT a common symptom of Alzheimer disease?

C, weight gain, is not a common symptom of Alzheimer's disease. Alzheimer's primarily affects cognitive functions and memory, leading to symptoms such as memory loss, personality changes, and disorientation. People with Alzheimer's often experience confusion about time and place, difficulty with tasks that were once familiar, and changes in behavior or personality that arise as the brain becomes increasingly compromised.

Memory loss is typically one of the first signs of the disease, leading many individuals to forget recent events or conversations. Personality changes can occur as the disease progresses, causing individuals to become more withdrawn, anxious, or irritable. Disorientation can also include confusion about time, places, or even familiar faces, making it a significant symptom in the progression of Alzheimer's.

In contrast, weight gain is not typically associated with the disease. Most individuals affected by Alzheimer's may experience weight loss or changes in appetite as a result of the cognitive decline, which could alter eating habits or lead to neglecting self-care. Thus, weight gain does not represent a common symptom of Alzheimer's.