Organic mental disorders: CSF biomarkers in Alzheimer disease: practice question

A Psychiatry question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Psychiatry · Organic mental disorders: CSF biomarkers in Alzheimer disease

Sample item

A 68-year-old woman has progressive memory loss over two years. A lumbar puncture is done to support the diagnosis of Alzheimer disease. Which CSF pattern is typical?

ALow amyloid-beta 42 with low tauBRaised amyloid-beta 42 with low tauCNormal amyloid and tau with raised 14-3-3 proteinDLow amyloid-beta 42 with raised total and phosphorylated tau

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

D. Low amyloid-beta 42 with raised total and phosphorylated tau

In Alzheimer disease amyloid-beta 42 falls in CSF because it is deposited in plaques, while total and phosphorylated tau rise with neuronal injury and tangles. Raised 14-3-3 protein suggests Creutzfeldt-Jakob disease.

Option by option

A. Low amyloid-beta 42 with low tau
Low tau is not seen, as tau is raised in Alzheimer disease.
B. Raised amyloid-beta 42 with low tau
Raised amyloid with low tau is the opposite of the Alzheimer pattern.
C. Normal amyloid and tau with raised 14-3-3 protein
Raised 14-3-3 with normal amyloid and tau suggests prion disease.
D. Low amyloid-beta 42 with raised total and phosphorylated tau (correct)
Correct. Low Abeta42 with high tau is the characteristic profile.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

Questions about this Psychiatry question

What is the answer to this Psychiatry question?

The best answer is D, Low amyloid-beta 42 with raised total and phosphorylated tau. In Alzheimer disease amyloid-beta 42 falls in CSF because it is deposited in plaques, while total and phosphorylated tau rise with neuronal injury and tangles.

Why is "Low amyloid-beta 42 with low tau" not the answer?

Low tau is not seen, as tau is raised in Alzheimer disease.

Why is "Raised amyloid-beta 42 with low tau" not the answer?

Raised amyloid with low tau is the opposite of the Alzheimer pattern.

Why is "Normal amyloid and tau with raised 14-3-3 protein" not the answer?

Raised 14-3-3 with normal amyloid and tau suggests prion disease.

What concept does this question test?

It tests Organic mental disorders: CSF biomarkers in Alzheimer disease in Psychiatry. Raised 14-3-3 protein suggests Creutzfeldt-Jakob disease.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Organic mental disorders: CSF biomarkers in Alzheimer disease?

Learn each diagnosis by its core features and its first-line treatment. Then use the flashcards and the other Psychiatry questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.