That image of a spiral sits at the heart of an alternative way of thinking about major depressive disorder. Developed across research involving Prof. Toine Pieters of the University of Utrecht and colleagues, it asks us to look beyond depression as primarily a collection of mood symptoms and instead examine how biology, psychology, behaviour and environment continually interact. The point is to ask whether a more dynamic map of depression could help explain why people arrive at similar diagnoses by very different routes, why treatments work well for some but not others, and where prevention might interrupt the process earlier.

This matters because depression is remarkably heterogeneous. Two people can receive the same diagnosis while sharing surprisingly few symptoms. One may sleep excessively while another barely sleeps. Appetite can rise or fall. Some people become visibly distressed, while others continue studying or working even as their internal resources are being depleted. A symptom checklist can identify suffering and guide care, but it does not necessarily reveal how that suffering developed.

An earlier study on adolescent depression offers a useful starting point. It focuses on stress, coping and exhaustion. Stress is more than simply an unpleasant feeling. It involves bodily systems designed to help us respond to demands and threats. One important component is the HPA axis, a network connecting the hypothalamus, pituitary gland and adrenal glands. Through hormones including cortisol, this system helps mobilise the body when challenges arise. In depression, dysregulation of this stress system is a recurring biological finding, although researchers still debate exactly when it is a cause, a consequence, or both.

The spiral model becomes especially intuitive when coping is added. Human beings constantly try to manage stress. We solve problems, seek reassurance, withdraw, work harder, avoid situations, change routines or attempt to regain control. These strategies may initially be useful. But if stressful demands continue, coping itself can become costly. A teenager who repeatedly pushes harder to meet expectations, for example, may sleep less and become increasingly exhausted. Another may retreat from friends or school to reduce immediate pressure. Such withdrawal can bring short-term relief while also shrinking sources of pleasure, confidence and support.

The adolescent case material behind this framework illustrates why the process matters. The young people described in the research presented very differently, with distinct symptoms and coping behaviours. Yet when clinicians looked beneath those surface differences, both histories contained a downward movement involving chronic stress, attempts to cope and mounting exhaustion. Understanding the sources of pressure, and how each young person responded to them, became important to personalised care. The lesson is that similar symptoms can emerge from different interacting pathways, while apparently different symptoms can conceal common dynamics.

This perspective also offers a provocative interpretation of anhedonia, the loss of interest or pleasure that is strongly associated with depression. Rather than seeing withdrawal and reduced motivation only as defects, the earlier work explores whether they may sometimes function as responses to overload, ways an exhausted organism reduces demands when continued coping has become unsustainable. This changes the question from simply “How do we remove this symptom?” to “What pressures and feedback loops are helping to produce and maintain it?”

More recent work broadens this picture dramatically. Beyond thoughts, emotions and social circumstances, the spiral may also involve the immune system, the body’s stress machinery and the vast microbial community in the gut. The microbiota-gut-brain axis describes the two-way communication linking gut microbes, the digestive system, immune signalling, hormones and the brain. Research reviewed by Pieters and colleagues highlights three repeatedly interconnected features: an overactive stress response, a pro-inflammatory state and disruption of the gut microbiome, known as dysbiosis.

These phenomena are interlinked. Cortisol can influence immune activity. Inflammatory signalling can affect the brain and stress system. The gut microbiome interacts with immune processes and produces substances that may influence bodily and neural function. Diet, sleep, exercise, substance use, illness and medication can intersect with these pathways. Meanwhile, trauma, loneliness, work or school pressure, financial insecurity and ineffective coping can add psychological and environmental strain. The model therefore replaces the search for one master cause with a network of influences that can amplify or restrain one another.

That shift is crucial. If depression is a moving system, the most useful clinical questions may be which combination of pressures is currently driving the spiral, which protective factors remain available, and where intervention has the best chance of changing direction, rather than which single abnormality explains a person’s condition.

This is why the model is genuinely biopsychosocial. Biology does not compete with psychology or social experience. Each level can alter the others over time, and feedback can move in more than one direction. A spiral can deepen, but it can also be interrupted.

Seen this way, prevention and treatment become less like striking a single target and more like changing the balance of a complex and multifaceted system. Psychotherapy might improve coping and reduce rumination. Medication might ease symptoms enough to restore sleep or motivation. Exercise may reduce stress and support sleep. Dietary changes might influence metabolic and gut-related processes. Social support can reduce isolation, while practical changes at school, work or home may remove chronic pressure. None has to be the one true answer. Their value may lie in how they work together.

That is why the model challenges the trial-and-error character of depression treatment. Current therapies can be effective, but many patients do not respond adequately to first-line antidepressants, and some continue to struggle after several attempts. A dynamic framework asks whether treatment choices could eventually be guided by a richer profile of each patient, including stress exposure, coping patterns, sleep, physical health, inflammation, gut-related biology, lifestyle and existing medication.

Diagnosis could change as well. Depression is currently identified mainly through symptoms and their effect on daily life. That is practical, but the newer framework raises the possibility that future diagnosis could combine symptoms with biological or behavioural indicators. Cortisol, inflammatory markers and features related to the microbiota-gut-brain axis are among the candidates being investigated. None is ready to function as a simple depression test, and depression is too heterogeneous to expect one universal biomarker. Still, combinations of signals might eventually help identify vulnerability before a severe episode develops.

That possibility makes prevention especially important. A spiral is easier to interrupt near its beginning than after many reinforcing loops have become established. Early warning signs might include deteriorating sleep, mounting exhaustion, persistent stress, declining activity or worsening coping. For an adolescent under relentless academic pressure, intervention might involve adjusting expectations, improving learning support and strengthening coping before withdrawal becomes entrenched. For someone affected by poor sleep, substance use, chronic illness or isolation, the most useful entry point could look completely different.

The framework therefore encourages a shift from asking only whether somebody meets the threshold for a disorder to asking how that person is moving through time. Are pressures accumulating? Are protective routines disappearing? Is exhaustion increasing? Which feedback loops are strengthening? What could be changed before the system becomes harder to reverse?

Yet a good model on paper is not enough. The researchers emphasise that the spiraling risk-factor model still requires clinical testing. Some biological evidence comes from animal research, many proposed biomarkers are not specific to depression, and studies vary in methods and quality. The model should therefore be treated as a research framework, not a finished explanation of every case.

For Prof. Toine Pieters, the next challenge is as much organisational as scientific. Depression research spans psychiatry, psychology, neuroscience, immunology, microbiology, pharmacology, public health and social science. Each field can reveal part of the picture, yet researchers and clinicians often work in parallel. This presents a “double spiral” problem: depression itself is interconnected, while the systems trying to understand it remain fragmented.

Breaking that second spiral may be essential to tackling the first. Cross-disciplinary dialogue could connect psychologists studying coping, immunologists studying inflammation, microbiome researchers, psychiatrists and social scientists. Translational care labs could bring these perspectives into real clinical settings, where ideas can be tested against the complexity of actual patient lives.

Equally important is the role of people with lived experience. Patient co-design panels could help researchers decide which questions matter, whether the model reflects real experiences, which measurements feel useful, and whether proposed interventions are practical.

That may be the most important philosophical change in this work. Rather than reframing depression to make it more abstract, this paradigm makes it more personal. A static label can tell us that someone is ill. A dynamic model tries to show how they arrived there, what keeps the illness going and where change might still be possible.

The spiral is therefore both a warning and a source of hope. Feedback loops can intensify distress, but feedback works in both directions. Better sleep can improve coping. Better coping can reduce stress. Reduced stress may support biological recovery. Restored activity can rebuild confidence and social connection. Small gains can reinforce further gains.

No single model will capture every form of depression. But by treating major depressive disorder as a changing biopsychosocial system rather than a fixed collection of symptoms, this framework opens new questions about prevention, diagnosis and care. Its greatest value may lie in giving researchers, clinicians and patients a shared map that can be tested, challenged and improved together.