A neuroimaging study conducted in the Netherlands has identified brain networks associated with specific cognitive functions in individuals with depression.
The study, published in Psychological Medicine, revealed that those with more severe depression symptoms generally exhibit weaker connectivity in the brain network linked to cognitive processing speed.
Major Depressive Disorder (MDD), commonly known as depression, is a serious mental health condition characterized by persistent feelings of sadness, hopelessness, and a lack of interest or pleasure in previously enjoyable activities.
It encompasses emotional and physical symptoms such as guilt, worthlessness, changes in appetite and sleep patterns, fatigue, difficulty concentrating, and thoughts of suicide.
Research indicates that depression not only affects mood but also impairs cognitive processes such as decision-making and attention.
It reduces memory effectiveness and processing speed, which in turn affects daily functioning and work performance. Cognitive impairments are increasingly recognized as significant adverse consequences of depression.
Study author Marius Gruber and colleagues aimed to investigate how changes in brain function contribute to cognitive impairments in depression.
They hypothesized that alterations in brain connectivity between regions responsible for cognitive function could be identified using diffusion-weighted imaging (DWI), an advanced imaging technique that visualizes white matter tracts by tracking the movement of water molecules in tissue.
Previous studies have shown that individuals with depression often exhibit reduced connectivity in specific brain regions and alterations in white matter structure.
The authors proposed a potential relationship between these cognitive deficits and changes in interconnected nerve cell networks (connectomes) in the brain.
The study involved 372 individuals experiencing a major depressive episode, 307 MDD patients in remission, and 805 healthy control participants, predominantly women with an average age between 34 and 37 years.
Participants underwent magnetic resonance imaging (MRI) to analyze connectomes and cognitive performance across processing speed, verbal learning and memory, and executive functioning.
Results indicated that both current MDD patients and those in remission performed worse than healthy participants in processing speed and verbal fluency tasks.
Participants currently in a depressive episode also exhibited poorer verbal learning and memory compared to healthy controls.
Cognitive performance across all domains correlated with the strength of connectivity in specific brain networks associated with each cognitive area, though these correlations were modest.
Furthermore, individuals in an active depressive state demonstrated weaker connectivity within the network linked to processing speed compared to healthy peers.
Those with more severe depression symptoms showed slower processing speed and reduced connectivity in this particular brain network.
In summarizing their findings, the authors concluded, “Our analyses confirmed significant cognitive deficits across multiple domains in major depressive disorder.
Based on network analyses, we demonstrated associations between cognitive performance and the structural connectome, highlighting domain-specific characteristics of these associations.
Importantly, structural connectome alterations within cognition-related subnetworks were observed in depression, suggesting a neurobiological basis for cognitive deficits in MDD.”
While shedding light on the neural mechanisms underlying depression-related cognitive impairments, the study also acknowledged limitations.
Specifically, since neuroimaging was conducted only once, it remains unclear whether these neural characteristics are stable or fluctuate over time.
