A new study examining the impact of depression on all five senses could significantly improve how the condition is diagnosed and treated, opening the door to more targeted solutions for patients.
Led by the University of New England’s Professor of Neuroscience, Christopher Sharpley, alongside colleagues Dr Lorenzo Odierna, Professor Vicki Bitsika, and Christopher Watson, the first-of-its-kind study highlights how depression is more than just a cognitive-emotional disorder.
“We found that sensory hyposensitivity occurred across all five major senses in depressed persons to a significantly greater extent than to non-depressed persons,” says Professor Sharpley.
“This had not been documented in such detail previously and shows how depression can trigger a whole-body response.”
Much like a runny nose attempts to flush invasive pathogens from the respiratory system, Professor Sharpley suggests sensory withdrawal is the body's way of coping with the pain, loss, stress, and conflict that can drive depression.
“When someone’s world becomes so painful or inescapable they can no longer cope, the only response our body has is to withdraw,” he says.
“One effective way to enact that withdrawal is to dull our senses so that information about the unpleasant world we find ourselves in is less intense—so a reduction in sensory sensitivity, or ‘sensory hyposensitivity’ (the loss of sensory acuity) occurs to achieve that withdrawal.”
To reach these findings, the research team reviewed 51 previous studies spanning each of the five senses, revealing a 'global' behavioural response across sight, touch, taste, hearing, and smell.
Image: UNE's Brain Behaviour Research Group. (L-R) Christopher Watson, Professor Vicki Bitsika, Professor Christopher Sharpley, Dr Lorenzo Odierna.
It is hoped that sensory withdrawal will be included in the major diagnostic criteria for depression in the future, paving the way for more comprehensive diagnosis and evidence-based treatment.
“When we visit our GP for a pain in our abdomen, we don’t accept that we should be given a diagnosis of ‘sore tummy’,” says Professor Sharpley.
“We expect that a trained medical practitioner will have a greater depth of knowledge about pain, illness, and the abdominal region.
“In the same way, mental health practitioners need to have a greater understanding of how the human body works than just to say to their patients that ‘you’re depressed’. The work that UNE is doing in this space will help achieve this.”
This study is one part of a broader body of work Professor Sharpley is involved in within the UNE Brain-Behaviour Research Group (BBRG), which is investigating how the human brain responds during depression.
“Using the BBRG’s electroencephalogram (EEG) lab, we’ve collected data from over 200 local Armidale residents and so far, we have been able to identify five depression ‘subtypes’ by their distinct brain wave patterns,” he says.
“Each of these depression subtypes needs specific treatment rather than a ‘one-size fits all’ pill or psychological therapy. Through this work, we will be able to form a model of depression in rural communities.”
Read more about the BBRG here, and find Professor Sharpley’s sensory hyposensitivity research that was published in Nature’s Translational Psychiatry Journal here.
