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Quiz: Anxiety, Depression, and the Gut

Test your understanding of Chapter 11. Choose the best answer, then click Show Answer to check.

Question 1

What does "psychiatric comorbidity" mean?

  1. A mental health condition caused directly by gut bacteria
  2. A medicine that treats both the gut and the brain
  3. A mental health condition occurring in a person who also has another health condition
  4. A doctor who specializes in both psychiatry and gastroenterology
Show Answer

The correct answer is C. Psychiatric comorbidity means having a mental health condition, such as anxiety or depression, alongside another health condition, such as IBD or IBS. It describes things occurring together and says nothing about cause, so option A adds a causal claim the term doesn't make.

Concept Tested: Psychiatric Comorbidity Bloom's Level: Remember

Question 2

According to the 2021 Barberio meta-analysis of 30,118 adults with IBD, about what share screened positive for anxiety symptoms?

  1. About one in three
  2. About one in ten
  3. About nine in ten
  4. About one in a hundred
Show Answer

The correct answer is A. The pooled prevalence of anxiety symptoms was 32.1%, about one in three, and depression symptoms were 25.2%, about one in four. These were questionnaire symptoms, not diagnosed disorders, and the study included adults only.

Concept Tested: Meta-Analysis Bloom's Level: Remember

Question 3

Which example best describes GI-specific anxiety?

  1. Feeling sad and losing interest in hobbies for several weeks
  2. Worrying about many everyday things, such as grades, friends, and the future
  3. Sudden panic attacks that come with no warning in any situation
  4. Fear focused on gut sensations, such as dreading a cramp in class and always checking where the restroom is
Show Answer

The correct answer is D. GI-specific anxiety is worry focused on gut symptoms and the situations where they might happen. Option B describes general, wide-ranging worry, which is different: someone can be calm about school and friends and still fear gut sensations.

Concept Tested: GI-Specific Anxiety Bloom's Level: Remember

Question 4

Why can't a high score on a symptom questionnaire, by itself, diagnose an anxiety disorder?

  1. Questionnaires are only used in mouse studies
  2. A questionnaire flags reported symptoms above a cutoff, while a diagnosis needs a full evaluation by a trained professional
  3. Questionnaire scores are always higher in people with IBD, so they are meaningless
  4. Anxiety disorders can only be diagnosed with a blood test
Show Answer

The correct answer is B. Questionnaires are quick screening tools that count symptoms; a diagnosis checks how long symptoms last, how much they interfere with life, and whether something else explains them. Option D is wrong: there is no blood test for anxiety disorders or depression.

Concept Tested: Symptom Questionnaire Bloom's Level: Understand

Question 5

A study finds that people with depression have lower levels of certain gut bacteria. Which explanation is an example of reverse causation?

  1. Depression changes appetite, food choices, and sleep, which then change the gut bacteria
  2. The low levels of bacteria cause the depression
  3. Poor sleep separately causes both depression and the bacteria change
  4. The bacteria and depression are linked by pure chance
Show Answer

The correct answer is A. The headline usually assumes bacteria cause depression; reverse causation means the arrow runs the other way, from depression to the bacteria. Option C describes a confounding variable (a third factor causing both), which is a different problem.

Concept Tested: Reverse Causation Bloom's Level: Understand

Question 6

A 2020 meta-analysis found that, on average, people with depression have higher blood levels of inflammation markers such as CRP and interleukin-6. What is the best interpretation?

  1. Every person with depression has high inflammation
  2. A blood test for CRP can now diagnose depression
  3. It supports the inflammatory depression theory as a link, but it shows an average shift and does not prove inflammation came first
  4. It proves that inflammation from the gut is the only cause of depression
Show Answer

The correct answer is C. The study showed a group-level shift in inflammation markers, which fits the theory that inflammation can push the brain toward depression in some people. But it measured blood at one time, so it can't show direction, and it doesn't apply to every individual. Option B is wrong because no blood test diagnoses depression.

Concept Tested: Inflammatory Depression Theory Bloom's Level: Understand

Question 7

Riya wants to know whether her anxiety tends to come before her Crohn's flares or after them. Which study design would best answer that question for people like her?

  1. A one-time survey of anxiety in 5,000 people with Crohn's disease
  2. A cohort study that measures anxiety and disease activity in the same people repeatedly over two years
  3. A study that moves gut microbes from people with Crohn's disease into germ-free mice
  4. A survey that asks people whether they think anxiety causes Crohn's
Show Answer

The correct answer is B. Following the same people over time lets researchers see whether anxiety measured earlier predicts flares later, and whether flares predict later anxiety, as the 2018 Gracie study did. Option A is large but is a single snapshot, so it can show that the two occur together but not which comes first.

Concept Tested: Cohort Study Bloom's Level: Apply

Question 8

A survey finds that students who sleep less than 6 hours a night report both more stomachaches and more anxiety. A classmate says, "Stomachaches must cause anxiety." What role does sleep most likely play here?

  1. It is the outcome being measured
  2. It proves the stomachaches cause anxiety
  3. It is an example of a microbiota transfer study
  4. It is a possible confounding variable that could cause both stomachaches and anxiety
Show Answer

The correct answer is D. Short sleep could worsen both gut symptoms and anxiety, creating a link between them even if neither causes the other. Option B gets it backward: a third factor that affects both makes it harder, not easier, to conclude that one causes the other.

Concept Tested: Confounding Variable Bloom's Level: Apply

Question 9

In a 12-year Australian cohort study, anxiety at the start predicted new functional gut disorders later, and gut disorders at the start predicted higher anxiety and depression later. What does this pattern best support?

  1. A bidirectional relationship between the brain and the gut
  2. Proof that anxiety causes all gut disorders
  3. Proof that gut disorders cause all anxiety
  4. That gut symptoms and anxiety are unrelated
Show Answer

The correct answer is A. Each direction predicted the other over time, which is the signature of a two-way street. Options B and C each pick only one direction and overstate it as proof; a cohort study shows prediction over time, and hidden confounders can't be fully ruled out.

Concept Tested: Bidirectional Relationship Bloom's Level: Analyze

Question 10

In The Two-Way Street MicroSim, setting gut to brain at 0.30 (with brain to gut at 0) and then switching to brain to gut at 0.30 (with gut to brain at 0) gives about the same snapshot correlation both times, but the "earlier, later" bars swap. What does this show?

  1. Snapshot surveys are better than cohort studies for finding direction
  2. The direction of an effect has no influence on any measurement
  3. A single snapshot can't reveal the direction, but following people over time can help
  4. A confounding variable must be present whenever two things are correlated
Show Answer

The correct answer is C. Opposite directions produce similar correlations at one moment, which is the reverse causation problem. The time-lagged correlations differ, which is why cohort studies help. Option D is wrong: in these settings there is no confounder at all, yet a correlation still appears.

Concept Tested: Reverse Causation Bloom's Level: Analyze