Mood disorders: delay in antidepressant action: 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 · Mood disorders: delay in antidepressant action

Sample item

Antidepressants raise synaptic monoamine levels within hours, yet clinical benefit takes two to four weeks. Which explanation is most widely proposed for this delay?

AGradual rise in cortisol levelsBTime needed for the liver to convert the drug into its prodrugCSlow adaptive changes such as receptor regulation and increased neurotrophic factor (BDNF) signallingDSlow absorption of the drug from the gut

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

The answer and the reasoning

C. Slow adaptive changes such as receptor regulation and increased neurotrophic factor (BDNF) signalling

The lag between early monoamine changes and clinical response suggests that downstream adaptations matter. These include receptor sensitivity changes and enhanced neuroplasticity and neurogenesis via BDNF and related signalling.

Option by option

A. Gradual rise in cortisol levels
Raised cortisol is a feature of depression and is not how antidepressants act.
B. Time needed for the liver to convert the drug into its prodrug
Most antidepressants are active drugs, not prodrugs needing conversion over weeks.
C. Slow adaptive changes such as receptor regulation and increased neurotrophic factor (BDNF) signalling (correct)
Correct. Neuroadaptive changes and BDNF-related plasticity are the leading explanation for delayed benefit.
D. Slow absorption of the drug from the gut
Antidepressants are absorbed within hours, so absorption cannot explain a lag of weeks.

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 C, Slow adaptive changes such as receptor regulation and increased neurotrophic factor (BDNF) signalling. The lag between early monoamine changes and clinical response suggests that downstream adaptations matter.

Why is "Gradual rise in cortisol levels" not the answer?

Raised cortisol is a feature of depression and is not how antidepressants act.

Why is "Time needed for the liver to convert the drug into its prodrug" not the answer?

Most antidepressants are active drugs, not prodrugs needing conversion over weeks.

Why is "Slow absorption of the drug from the gut" not the answer?

Antidepressants are absorbed within hours, so absorption cannot explain a lag of weeks.

What concept does this question test?

It tests Mood disorders: delay in antidepressant action in Psychiatry. These include receptor sensitivity changes and enhanced neuroplasticity and neurogenesis via BDNF and related signalling.

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 Mood disorders: delay in antidepressant action?

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.