Depression is a heterogeneous condition in which the symptoms of two patients may differ markedly. This highlights the need to develop more effective methods for diagnosing depression. At present, diagnosis is based on symptoms identified during a clinical interview, and research has not yet identified objective biomarkers that could be used alongside the clinical interview in diagnosing depression.
Potential biological indicators of depression are being actively investigated. This dissertation examined depression related alterations in the processing of sensory stimuli by measuring event related potentials of the brain using electroencephalography.
In the empirical study reported in MSc Elina Kangas' dissertation, brain activity in response to auditory stimuli presented at different intensities differed in the depression group, in which participants were not using antidepressant medication, compared with non depressed control participants. This so called intensity dependence response has been suggested to reflect the functioning of the brain’s serotonin system, which has been linked to depression. However, the findings of the review article included in the dissertation were not entirely consistent with this result: several studies did not observe a similar group difference. The results of the dissertation did not demonstrate differences between the depression group and the non depressed group in brain activity reflecting automatic deviance detection, despite earlier studies reporting such alterations in psychiatric disorders.
Overall, the findings of the dissertation suggest that it is unlikely that a single brain activity component could serve as a biomarker for depression. Future research should focus on examining combinations of biomarkers, integrating, for example, neurophysiological, peripheral, and genetic indicators.
The neurophysiological approach applied in the dissertation represents one of many perspectives on depression research. Depression should be studied within a broad framework that encompasses psychological, social, and biological factors and their interactions. Progress across all these research domains could lead to more precise diagnostic practices and more individualised treatment approaches. Thus, the direction would be towards a personalised medicine perspective in the treatment of depression.
MSc Elina Kangas defends her doctoral dissertation ”Evaluating auditory and somatosensory event-related potentials as neural markers of depression” on Saturday, February 21, 2026 at 12 o’clock in Main building, hall C4. Opponent is PhD, Academy Research Fellow Vesa Putkinen (University of Turku) and custos is Professor Piia Astikainen (University of Jyväskylä). The event will be held in Finnish.
The dissertation is available in the JYX archive at http://urn.fi/URN:ISBN:978-952-86-1293-3
