How Does Depression Arise and Recur?

Symptoms, vulnerability, circumstances, biological pathways, and the course of depression.

Level: Intermediate
Reading load: 10 core readings in 5 units
Prerequisites: Begin with What Is a Mental Disorder? and How Do Psychological Disorders Develop and Persist?, or bring equivalent familiarity with classification, risk factors, and causal inference. Basic familiarity with correlation and experimental comparisons is useful. Guidance introduces the longitudinal, twin, and trial designs; reproducing statistical calculations is not required.
Last reviewed: September 2026

Introduction

Depression has recognizable features, yet lives gathered under the same diagnosis can differ in symptoms, circumstances, and course. An explanation must choose its question carefully. Is it addressing a symptom, the beginning of an episode, continuing impairment, improvement, or recurrence after recovery? These events belong to a connected history without necessarily sharing the same causes.

This path moves from the measurement problem to ways of thinking that might increase vulnerability, stressful environments, and the ways depression and interactions with other people may affect one another, then examines inflammation as one worked biological example. It ends by comparing claims about long-lasting difficulties with an intervention in Indian primary care and a trial of recurrence prevention. Conceptual papers define the questions; observational studies and experiments expose what particular comparisons can answer.

By the end, you should be able to distinguish prediction from causal explanation, evaluate the fit between a theory and its measures, identify sampling assumptions behind a prognosis, and explain why an effective intervention does not automatically reveal the original cause or its own mechanism. The ten works differ in difficulty, with the theory review and causal designs asking for especially close attention.

Unit 1 of 5

What are we trying to explain?

Before comparing causes, decide what counts as the outcome. Fried and Nesse ask what is lost when distinct symptoms become one number. Carry this measurement question into every later comparison: the same word, depression, may refer to different observations.

Reading
1 of 10
Depression Sum-Scores Don’t Add Up
Fried, E. I., & Nesse, R. M. (2015). Depression sum-scores don’t add up: Why analyzing specific depression symptoms is essential. BMC Medicine, 13, Article 72. https://doi.org/10.1186/s12916-015-0325-4
Critical reappraisal · Methodological contribution · Moderate · Full work: 11 pages
Track how symptom patterns can differ even when the diagnosis or total score agrees.
Why you’re reading it. Establish the outcome distinctions that the later explanatory and intervention papers will need.
A question to consider. Two people have equal depression scores, but one reports insomnia and agitation while the other reports excessive sleep and slowing. What information should an explanatory study retain beyond the total?

Unit 2 of 5

What makes someone vulnerable?

A theory should specify more than a list of associated characteristics. Liu and colleagues lay out an explanatory chain and assess its uneven evidence. Alloy and colleagues then provide a prospective comparison: earlier cognitive characteristics predict later episodes, but the grouping combines constructs and does not test every link in the theory.

Reading
2 of 10
The Hopelessness Theory of Depression: A Quarter-Century in Review
Liu, R. T., Kleiman, E. M., Nestor, B. A., & Cheek, S. M. (2015). The hopelessness theory of depression: A quarter-century in review. Clinical Psychology: Science and Practice, 22(4), 345–365. https://doi.org/10.1111/cpsp.12125
Major synthesis · Challenging · Full work: 21 pages
Separate the proposed vulnerability, stressful event, intervening hopelessness, and depressive outcome.
Why you’re reading it. Build a framework whose individual links can be compared with what a study actually measures.
A question to consider. What observations and measurement times would be needed to distinguish “inferential style predicts depression” from the proposed vulnerability–stress–hopelessness pathway?
Reading
3 of 10
Prospective Incidence of Depression at High and Low Cognitive Risk
Alloy, L. B., Abramson, L. Y., Whitehouse, W. G., Hogan, M. E., Panzarella, C., & Rose, D. T. (2006). Prospective incidence of first onsets and recurrences of depression in individuals at high and low cognitive risk for depression. Journal of Abnormal Psychology, 115(1), 145–156. https://doi.org/10.1037/0021-843x.115.1.145
Landmark empirical study · Methodological contribution · Challenging · Full work: 12 pages
Compare the theory’s required evidence with the study’s combined cognitive-risk groups and repeated diagnostic interviews.
Why you’re reading it. Learn what temporal precedence contributes while recognizing the difference between testing a predictor and testing a full mechanism.
A question to consider. Which parts of the preceding theory could this cohort support, and which would require measurements or comparisons not reported in this article?

Unit 3 of 5

How do depression and circumstances affect each other?

Vulnerability takes shape within developmental histories and present circumstances. Hammen connects chronic adversity, discrete events, and interpersonal feedback. Kendler and colleagues use co-twin comparisons to probe whether event associations can be explained by shared vulnerability. Their design reduces some alternatives without eliminating every one.

Reading
4 of 10
Stress and Depression: Old Questions, New Approaches
Hammen, C. L. (2015). Stress and depression: Old questions, new approaches. Current Opinion in Psychology, 4, 80–85. https://doi.org/10.1016/j.copsyc.2014.12.024
Major synthesis · Moderate · Full work: 6 pages
Follow how the timing and measurement of adversity alter the explanation, including paths from depression to later circumstances.
Why you’re reading it. Extend the cognitive framework to development, chronic conditions, and reciprocal interpersonal processes.
A question to consider. If financial strain, conflict, and depressive symptoms rise together, sketch two different directions of influence and name evidence that could help separate them.
Reading
5 of 10
Stressful Life Events and the Onset of Major Depression
Kendler, K. S., Karkowski, L. M., & Prescott, C. A. (1999). Causal relationship between stressful life events and the onset of major depression. American Journal of Psychiatry, 156(6), 837–841. https://doi.org/10.1176/ajp.156.6.837
Methodological contribution · Challenging · Full work: 5 pages
Identify the alternatives removed by comparing identical twins and those left by retrospective event ratings and unshared circumstances.
Why you’re reading it. Apply the earlier causal questions to a specific observational strategy.
A question to consider. Does finding an association within identical-twin pairs settle the direction of the feedback proposed by Hammen? Explain which uncertainty remains.

Unit 4 of 5

What would establish a biological pathway?

Biological explanation needs a path from process to observation, not simply a bodily correlate. Dantzer and colleagues examine immune-to-brain communication and distinguish sickness from depression. Raison and colleagues test one intervention on a related pathway. This pair is a bounded example of biological reasoning, not a claim that all depression is inflammatory.

Reading
6 of 10
From Inflammation to Sickness and Depression
Dantzer, R., O'Connor, J. C., Freund, G. G., Johnson, R. W., & Kelley, K. W. (2008). From inflammation to sickness and depression: When the immune system subjugates the brain. Nature Reviews Neuroscience, 9(1), 46–56. https://doi.org/10.1038/nrn2297
Major synthesis · Foundational argument · Challenging · Full work: 11 pages
Separate mechanisms of immune communication, behavioral observations in animals, and depressive outcomes in humans.
Why you’re reading it. Build the biological proposal that the next trial subjects to a clinical comparison.
A question to consider. What evidence would distinguish inflammation contributing to a particular depressive symptom from inflammation merely accompanying illness or distress?
Reading
7 of 10
Infliximab for Treatment-Resistant Depression
Raison, C. L., Rutherford, R. E., Woolwine, B. J., Shuo, C., Schettler, P., Drake, D. F., Haroon, E., & Miller, A. H. (2013). A randomized controlled trial of the tumor necrosis factor antagonist infliximab for treatment-resistant depression: The role of baseline inflammatory biomarkers. JAMA Psychiatry, 70(1), 31–41. https://doi.org/10.1001/2013.jamapsychiatry.4
Methodological contribution · Challenging · Full work: 11 pages
Interpret the overall randomized result before considering the exploratory inflammatory subgroup.
Why you’re reading it. Test how far a plausible pathway can carry a treatment prediction, and where a new hypothesis requires new data.
A question to consider. How should the negative overall result and data-selected subgroup affect your confidence in different claims from the preceding review?

Unit 5 of 5

What do improvement and recurrence reveal?

A sample’s history matters when explaining its future. Monroe and Harkness question broad chronicity claims derived from selected cases. Patel and colleagues examine acute improvement in Goa, while Teasdale and colleagues examine prevention after remission. Compare their populations, outcomes, and controls before treating their results as evidence about the same process.

Reading
8 of 10
Is Depression a Chronic Mental Illness?
Monroe, S. M., & Harkness, K. L. (2012). Is depression a chronic mental illness? Psychological Medicine, 42(5), 899–902. https://doi.org/10.1017/s0033291711002066
Critical reappraisal · Accessible · Full work: 4 pages
Distinguish predicting another episode in a recurrent sample from predicting which first episodes will become recurrent.
Why you’re reading it. Set the population and time-course questions needed to interpret the two intervention trials.
A question to consider. What could go wrong if a recurrence estimate from a specialist clinic were used to describe everyone experiencing a first episode?
Reading
9 of 10
The Healthy Activity Program in Primary Care in India
Patel, V., Weobong, B., Weiss, H. A., Anand, A., Bhat, B., Katti, B., Dimidjian, S., Araya, R., Hollon, S. D., King, M., Vijayakumar, L., Park, A.-L., McDaid, D., Wilson, T., Velleman, R., Kirkwood, B. R., & Fairburn, C. G. (2017). The Healthy Activity Program (HAP), a lay counsellor-delivered brief psychological treatment for severe depression, in primary care in India: A randomised controlled trial. The Lancet, 389(10065), 176–185. https://doi.org/10.1016/s0140-6736(16)31589-6
Landmark empirical study · Moderate · Full work: 10 pages
Examine how the care setting, training, adaptation, and outcome definitions shape the treatment comparison.
Why you’re reading it. Connect change to social context while separating efficacy, mechanism, and the original cause of depression.
A question to consider. If HAP improves remission and functioning, which additional evidence would show that increasing activity mediated the effect rather than simply changing alongside it?
Reading
10 of 10
Prevention of Depressive Relapse by Mindfulness-Based Cognitive Therapy
Teasdale, J. D., Segal, Z. V., Williams, J. M. G., Ridgeway, V. A., Soulsby, J. M., & Lau, M. A. (2000). Prevention of relapse/recurrence in major depression by mindfulness-based cognitive therapy. Journal of Consulting and Clinical Psychology, 68(4), 615–623. https://doi.org/10.1037/0022-006x.68.4.615
Landmark empirical study · Moderate · Full work: 9 pages
Compare a remitted, recurrent sample and a prevention outcome with the acute-change question in Goa.
Why you’re reading it. Complete the distinction between onset, improvement, and recurrence without assuming they share one mechanism.
A question to consider. What conclusions can you draw across the two trials about changing the course of depression, and which differences prevent a direct comparison of their effects?

Scope and omissions

This is an explanatory path focused primarily on unipolar depression, not a diagnostic manual, an individual prognosis, or a treatment-selection guide. One immune-treatment trial includes participants with bipolar depression; its mixed sample is part of the critical reading. The core spans measurement, cognition, development, adversity, interpersonal processes, a biological pathway, and service context.

It does not survey every genetic, neural, endocrine, sleep, or psychological account, nor provide comprehensive coverage of childhood, perinatal, or later-life depression. The largely European and North American literature is supplemented by the Goa trial, which adds a consequential setting rather than establishing worldwide generality. Chronicity, cultural meaning, severe comorbidity, and variation within diagnostic groups require more evidence than this selection can provide.

Synthesis

The readings offer several possible pathways into depression and recurrence, whose relevance may differ across people, symptoms, and periods of life. Cognitive styles can precede episodes; stressful circumstances can contribute to difficulty and be shaped by it; bodily processes can alter behavior. These are specific proposals to investigate, rather than one established chain into which every depressive experience must fit.

The strength of an explanation depends on the match between its claim and its evidence. Prospective prediction does not remove all confounding. A co-twin comparison addresses shared influences while leaving others. A plausible pathway and a favorable exploratory subgroup do not establish a general treatment effect. An intervention can improve outcomes without isolating its mechanism or identifying what originally caused them.

Course also depends on whom we observe and for how long. Improvement during an episode and prevention after remission are distinct achievements, and an estimate from recurrent clinical cases is not everyone’s prognosis. As a final exercise, choose one proposed pathway and specify its outcome, population, temporal order, strongest available comparison, and most important remaining alternative explanation.

For the broader process framework, return to How Do Psychological Disorders Develop and Persist?. To extend the biological question beyond depression, follow How Do Brain and Body Regulate Each Other?. Other clinical questions are organized in Psychopathology.

To examine depressive phases alongside mania, hypomania, and changes in activation, follow What Explains Mood Episodes in Bipolar Disorder?. It compares explanations of first onset, changing mood, and recurrence without assuming that bipolar disorder follows a regular cycle.