Researchers at the University of Helsinki have identified five patterns of brain activity among people diagnosed with depression, finding that patients with the same diagnosis showed differences in communication between brain regions.
The study involved 263 people with depression and 75 healthy participants. Researchers divided patients into five groups based on the strength and frequency of functional connections between different parts of the brain.
Some of the patterns moved in opposite directions. Connections between brain regions were stronger than usual among some participants and weaker among others.
“What was particularly interesting was how opposing patterns of brain activity were found within the same depression diagnosis,” Satu Palva, director at the University of Helsinki’s Neuroscience Center said.
Functional connectivity measures how closely different brain regions operate at the same time and provides information about communication between them.
The researchers found links between the five brain profiles and differences in symptoms.
One group showed moderately strong connectivity and reported a range of symptoms including depression, anxiety, worry and reduced functioning.
A second group had weaker connectivity and generally reported milder symptoms. A third showed weak connectivity across a wider area of the brain and had more symptoms associated with post-traumatic stress.
The fourth group showed a mixture of weak and strong connections. Participants in this group had more severe depression, greater substance use and lower reported wellbeing.
The fifth group had the strongest connectivity of the five. Substance use was more common in this group, while trauma-related symptoms were less prominent.
All five groups also differed from the healthy comparison group. Differences involved both the strength of connections and the brain regions and frequencies involved.
Researchers used magnetoencephalography, known as MEG, to record brain activity. The technique measures magnetic fields generated by electrical activity in the brain.
Palva said MEG allowed the team to follow electrical brain activity with millisecond precision, providing a faster measure than methods previously used to investigate depression subtypes.
The findings offer one possible explanation for conflicting results in earlier studies of the biology of depression. People receiving the same clinical diagnosis could have different, and in some cases opposing, patterns of brain activity.
The research does not provide a method for choosing treatments based on a patient’s brain profile.
“We are not yet at the point where a brain measurement could be used to select the right treatment for a patient, but the study shows one possible route towards that,” Palva said.
Researchers aim in the longer term to establish stronger links between symptoms, patterns of brain activity and treatment response.
The World Health Organization estimated in 2025 that depression affected about 332 million people, or 5.7 per cent of adults worldwide. In Finland, depression is the single most common reason for both long-term sickness absence and disability pensions, according to the University of Helsinki.
HT