**Question:** Regarding Alzheimer's disease which is/are not true:

A. Alzheimer's disease primarily affects older adults.
B. Alzheimer's disease is caused by a single genetic mutation.
C. Alzheimer's disease is a reversible condition.
D. Alzheimer's disease primarily affects memory but does not impact cognitive abilities.

**Core Concept:** Alzheimer's disease is a progressive neurodegenerative disorder characterized by the accumulation of amyloid-beta plaques and neurofibrillary tangles in the brain, leading to neuronal dysfunction and death, ultimately affecting memory, cognition, and behavior.

**Why the Correct Answer is Right:**

Correct Answer: **D**. Alzheimer's disease primarily affects older adults (over 65 years) due to the increased risk of developing the disease with age. Alzheimer's disease is not caused by a single genetic mutation but results from a complex interplay of genetic, environmental, and lifestyle factors. Alzheimer's disease is generally considered a non-reversible condition, as the disease progresses and neuron damage occurs. Although Alzheimer's disease primarily affects memory, the cognitive decline also impacts other cognitive abilities, such as language, spatial awareness, and executive functions.

**Why Each Wrong Option is Incorrect:**

A. Alzheimer's disease affects individuals of various ages, not just older adults.
B. Alzheimer's disease is primarily caused by the accumulation of amyloid-beta plaques and neurofibrillary tangles, rather than a single genetic mutation.
C. Alzheimer's disease is a reversible condition, which is not true considering its progressive nature and neuronal damage.
D. Alzheimer's disease primarily affects memory, but also impacts other cognitive abilities and not just memory alone.

**Clinical Pearl:** Understanding the multifactorial etiology of Alzheimer's disease contributes to the management strategies involving lifestyle modifications, pharmacological interventions, and supportive care for patients and their caregivers.