Which of the following is not true about Alzheimer’s disease?

Explanation

## Correct Answer: B. Nucleus of Meynert is not affected The nucleus of Meynert (basal nucleus of Meynert) is **specifically and severely affected** in Alzheimer's disease, making option B factually incorrect. This nucleus, located in the basal forebrain, contains cholinergic neurons that project widely to the cerebral cortex and are critical for cognition and memory. In Alzheimer's disease, there is marked degeneration and loss of cholinergic neurons in the nucleus of Meynert, leading to significant reduction in acetylcholine levels—a key neurochemical deficit that contributes to the cognitive decline and memory impairment seen clinically. This cholinergic deficit is the rationale for using acetylcholinesterase inhibitors (donepezil, rivastigmine, galantamine) as symptomatic treatment in Indian clinical practice. The question tests whether students understand the **pathological hallmarks of Alzheimer's disease** and can distinguish true features from false statements. Since the nucleus of Meynert IS affected (not spared), option B is the correct answer to "which is NOT true." ## Why the other options are wrong **A. Short term memory is affected** — This is TRUE and a cardinal feature of Alzheimer's disease. Memory loss—particularly short-term/working memory initially, progressing to long-term memory—is the hallmark presenting symptom in Indian patients. This is not the answer because the question asks what is NOT true. Students may confuse early-stage presentation (where short-term memory is more prominent) with late-stage disease, but memory impairment is always present. **C. Intracellular neurofibrillary tangles are seen** — This is TRUE and a pathological hallmark of Alzheimer's disease. Neurofibrillary tangles (composed of hyperphosphorylated tau protein) are found intracellularly and are one of the two defining neuropathological features (along with amyloid plaques). This is not the answer because tangles ARE present in Alzheimer's disease. NBE may include this to test if students confuse tau pathology with other dementias. **D. Neuritic plaques made of beta amyloid are found** — This is TRUE and the second major pathological hallmark of Alzheimer's disease. Amyloid-beta (Aβ42) accumulates extracellularly to form senile/neuritic plaques, which is central to the amyloid hypothesis of Alzheimer's pathogenesis. This is not the answer because plaques ARE a defining feature. The amyloid cascade is the basis for emerging therapies like aducanumab being studied in Indian research centers. ## High-Yield Facts - **Nucleus of Meynert** is severely affected in Alzheimer's disease with loss of cholinergic neurons, leading to reduced acetylcholine and cognitive decline. - **Neurofibrillary tangles** (hyperphosphorylated tau) and **amyloid-beta plaques** are the two pathological hallmarks required for neuropathological diagnosis of Alzheimer's disease. - **Acetylcholinesterase inhibitors** (donepezil, rivastigmine, galantamine) are the DOC for symptomatic treatment in India, targeting the cholinergic deficit from nucleus of Meynert degeneration. - **Short-term/working memory** is typically affected early in Alzheimer's disease, followed by progressive loss of long-term memory and other cognitive domains. - **Amyloid-beta 42 (Aβ42)** is the primary component of extracellular neuritic plaques; elevated CSF phospho-tau and low Aβ42 are biomarkers for Alzheimer's disease. ## Mnemonics **NAPE for Alzheimer's Neuropathology** **N**ucleus of Meynert (cholinergic loss) → **A**myloid plaques (extracellular Aβ) → **P**hosphorylated tau (intracellular tangles) → **E**arly memory loss. Use this to remember all four pathological features and their sequence. **Memory hook: 'Meynert is LOST in Alzheimer's'** The nucleus of Meynert is **L**ost (degenerated), **O**ften affecting **S**hort-term memory, **T**au and amyloid accumulate. Helps recall that Meynert IS affected, not spared. ## NBE Trap NBE pairs "nucleus of Meynert is NOT affected" with three true statements about Alzheimer's to trap students who either (1) confuse Meynert involvement with other dementias where it is spared, or (2) misread the question stem and select a true feature instead of identifying the false statement. ## Clinical Pearl In Indian clinical practice, when an elderly patient presents with progressive memory loss and cognitive decline, the finding of severe cholinergic deficiency (from nucleus of Meynert degeneration) guides us to prescribe acetylcholinesterase inhibitors—a practical application of understanding this neuropathology. Patients often show modest but meaningful improvement in cognition and functional capacity with these agents, reinforcing the importance of the Meynert-cholinergic axis in Alzheimer's disease. _Reference: Robbins & Cotran Pathologic Basis of Disease, Ch. 28 (Nervous System); Harrison's Principles of Internal Medicine, Ch. 442 (Dementia); OP Ghai Essentials of Psychiatry (Indian context on cholinergic hypothesis and acetylcholinesterase inhibitors)_