Brain Scans Reveal Common Neural Circuit for Insomnia, Anxiety and Depression
A study finds shared and distinct brain features in insomnia, depression and anxiety, suggesting a common neural circuit.
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A recent study from the Netherlands Institute for Neuroscience, in collaboration with Vrije Universiteit Amsterdam, has examined the similarities and differences between three common mental disorders: insomnia, depression and anxiety. These conditions are highly prevalent, and their treatments often provide only moderate relief, with many individuals experiencing recurring symptoms. As such, understanding shared mechanisms between these disorders could lead to more effective treatments.
Brain scans reveal overlapping and unique features
The research team, led by Siemon de Lange, Elleke Tissink and Eus van Someren, analyzed brain scans from more than 40,000 participants in the UK Biobank to investigate the brain structures and connectivity patterns associated with insomnia, depression and anxiety.
The findings revealed several overlapping features in the brain's structure and connectivity across all three disorders. Specifically, the researchers found a reduced surface area in the cerebral cortex, a smaller thalamic volume and weaker connectivity between various brain regions. These structural changes were consistent across insomnia, depression and anxiety, suggesting a shared brain mechanism that may contribute to the comorbidity of these conditions.
Cerebral cortex
The outer layer of the brain involved in numerous functions, including sensory perception, motor control and higher cognitive functions such as language and emotion.
Thalamus
A brain structure responsible for relaying sensory and motor signals to the cerebral cortex.
Distinct brain abnormalities linked to disorder severity
While there were common features across the disorders, the study also highlighted unique abnormalities linked to the severity of each condition. For insomnia, severity was most strongly associated with smaller volumes in brain regions linked to reward processing. Depression, on the other hand, showed a stronger relationship with a thinner cerebral cortex in areas involved in language and emotion. In anxiety, severity correlated with weaker amygdala reactivity and impaired connectivity between regions where neurotransmitters like dopamine, glutamate and histamine are crucial for communication.
Amygdala
A brain region involved in processing emotions, particularly fear, and regulating emotional responses.
Neurotransmitters
Chemical substances, such as dopamine, glutamate and histamine, that transmit signals across synapses between nerve cells in the brain.
A shared brain circuit
Despite the unique abnormalities, the researchers observed that the affected brain regions appear to form part of the same brain circuit: the amygdala–hippocampus–medial prefrontal cortex circuit. This suggests that while the disorders affect different parts of the brain, they all share vulnerabilities within a common neural network.
Prefrontal cortex
The part of the brain associated with decision-making, social behavior and regulating emotions.
"The regions seem separate from each other, but when you map them out together, they all turn out to be part of the same circuit (amygdala–hippocampus–medial prefrontal cortex circuit). So, even though they are distinct areas, they all appear to represent different pieces of vulnerability within the same puzzle."
Dr. Elleke Tissink.
The study's findings are significant in understanding how these disorders overlap. Traditionally, much research has focused on the overlap between anxiety and depression, often overlooking insomnia. This is the first large-scale study to investigate all three disorders simultaneously. The high rate of comorbidity – people often experience these disorders at different stages of their lives or simultaneously – adds complexity to understanding their underlying mechanisms.
Implications for treatment
One of the intriguing aspects of this research is its potential to explain why treating insomnia can sometimes alleviate depression. The shared brain mechanisms suggest that improving one disorder might positively affect another. Tissink hopes that these findings will lead to new avenues for further research and better treatment strategies for insomnia, depression and anxiety.
Reference: de Lange SC, Tissink E, Bresser T, et al. Multimodal brain imaging of insomnia, depression and anxiety symptoms indicates transdiagnostic commonalities and differences. Nat Mental Health. 2025. doi: 10.1038/s44220-025-00412-8
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