A study analysing the subtype groupings of depression has found that patients with varying symptoms respond differently to CBT treatment.
According to the World Health Organisation (WHO), the global burden of depression is on the rise and is a leading cause and contributor to disability and disease. Recent worldwide estimates published in 2018 approximate that 264 million people of all ages suffer from depression.
Additionally, although there are known effective treatments for the condition, between 76% and 85% of people in low- and middle-income countries receive no treatment. And of those who are lucky enough to live in countries with the resources, and the de-stigmatised culture, to receive treatment, recovery is not guaranteed, and recurrence is common.
Part of the reason why depression can be hard to treat is that it presents in a variety of symptoms, which are treated by a range of different methods. Traditionally treatment is based on whether the symptoms are cognitive (low mood, negative thoughts), affective (loss of pleasure and motivation), and somatic (difficult with sleep and changes in appetite).
It is widely acknowledged that the current diagnostic system often fails to capture the diverse character of depression, as not all patients will experience all the symptom groups. And therefore, the success of the multitude of different treatment options will be heavily mixed and reliant on individual symptoms.
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More needs to be done to precisely diagnose mental health conditions
Correspondingly, aiming to improve clinical outcomes, researchers at the University of Sheffield and leso Digital Health have analysed the type and severity of symptoms of more than 8,000 patients and have found that five distinct subtypes respond differently to treatment by Cognitive Behavioural Therapy (CBT).
The five broad subtypes of depression identified in the study were:
- Mild: Minimal symptoms, a state of mild overall severity of depression (2.7% of patients).
- Severe: A serious state of depression, people typically experience all symptoms at a very elevated level (9.8% of patients).
- Cognitive-affective: Intense feelings of depression, tiredness and low self-esteem. People may have repetitive negative thoughts and struggle to feel pleasure in activities they usually enjoy and lack motivation (23.7% of patients).
- Somatic: Difficulties sleeping, feeling of tiredness and changes in appetite, as well as psychomotor disturbances such as restlessness, fidgeting and pacing (21.4% of patients).
- Typical: Patients experience a combination of both cognitive-affective and somatic symptoms to varying degrees of severity (42.4% of patients).
Analysis of patients and their subtype response to CBT treatment revealed that cognitive-affective patients were more likely to engage, attend more session, and overall improve, compared to patients whose depression was classed as somatic or typical.
Moreover, patients with a typical subtype were more likely to drop out of treatment altogether than those with cognitive-affective and somatic subtypes – indicating that for four in ten patients, CBT wasn’t necessarily the best treatment option.
Dr Melanie Simmonds-Buckley, University of Sheffield, lead author on the paper, commented on the findings: “Given how different depression can be from one person to the next, a treatment that works for one person may not work as well for another. Our findings have helped to identify how symptom profiles can be grouped into replicable subtypes of depression, showing that not all patients respond to CBT treatment in the same way.”
She added that future research would be concentrated on how other treatment options interact with the subtype groupings to assist in a more precise diagnosis and treatment selection, leading to improved outcomes for patients.
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