Depression can affect people in remarkably different ways. Some experience persistent anxiety and repetitive negative thoughts, while others struggle with trauma-related symptoms, reduced motivation, or difficulties managing everyday responsibilities.
Although these experiences may fall under the same diagnosis, the biological processes associated with them may not be identical.
A study led by researchers at the University of Helsinki, published in Nature Mental Health in 2026, has identified five distinct patterns of brain activity among people diagnosed with major depressive disorder. The findings suggest that depression may involve several different forms of brain network disruption rather than one universal biological pattern.
<h3>Why Depression May Have Different Biological Forms</h3>
Major depressive disorder can involve persistent sadness, anxiety, reduced enjoyment, changes in concentration, and difficulties functioning in daily life. The combination and intensity of these symptoms vary considerably between individuals. Researchers have increasingly investigated functional connectivity, which describes how activity in different brain regions coordinates over time. These regions operate through interconnected networks that support attention, emotional processing, memory, and decision-making.
Some previous studies have associated depression with unusually strong communication between certain brain networks, while others have reported weaker connections. Such apparently conflicting findings have made it difficult to identify one consistent pattern. The Helsinki research team proposed that these differences might reflect distinct subgroups of depression rather than contradictory results.
<h3>Five Distinct Patterns Emerge From Brain Scans</h3>
The study examined 263 people diagnosed with major depressive disorder and compared their results with those of 75 healthy participants. Using statistical methods, researchers grouped the clinical participants according to their brain connectivity measurements and associated symptom profiles.
Five main patterns emerged, each showing a different combination of brain network activity and reported symptoms. One group displayed moderately increased connectivity alongside more pronounced symptoms across several areas, including depression, anxiety, repetitive negative thinking, and difficulties with daily functioning.
A second group showed generally weaker connectivity and comparatively milder symptoms. A third demonstrated widespread reductions in connectivity alongside more prominent trauma-related symptoms. The fourth group presented a mixed pattern, with some connections stronger and others weaker. Participants in this group tended to report more severe depressive symptoms, greater substance-related difficulties, and lower overall well-being.
The fifth group displayed the strongest connectivity across the identified profiles. Substance-related symptoms were particularly prominent, while trauma-related symptoms were less pronounced than in some other groups. These categories do not mean that every person with depression fits neatly into one permanent type. Instead, they represent patterns identified through statistical analysis of a particular research sample.
<h3>How Magnetoencephalography Reveals Brain Activity</h3>
To investigate these differences, researchers used magnetoencephalography, commonly abbreviated as MEG. This technology measures extremely weak magnetic fields generated by electrical activity in the brain. Unlike imaging techniques that primarily track slower changes associated with blood oxygen levels, MEG captures neural activity with millisecond precision. This allows scientists to examine rapid rhythms and coordination between brain regions.
<h3>Expert Insight</h3>
Satu Palva, director of the Neuroscience Center at the University of Helsinki and a researcher involved in the study, highlighted the contrasting findings. In the university's report published by ScienceDaily, Palva stated: “What was particularly interesting was the contrasting patterns of brain activity found under the umbrella of the same depression diagnoses. In some individuals, the functional connectivity between brain regions was stronger than usual, while in others it was weaker.”
The University of Helsinki study provides evidence that major depressive disorder can involve five distinct patterns of brain connectivity, each associated with different combinations of symptoms. Future investigations may clarify how these patterns develop, whether they change during recovery, and how they could eventually help clinicians match patients with appropriate care.
