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Study: The three subtypes of depression
The exact causes of depression are still unclear, although around 300 million people worldwide suffer from the mental illness. A team of Japanese researchers has come a whole step closer to deciphering this puzzle. The researchers were able to divide the depression into three different forms. In one of these forms, medication has no effect.
A team from the Neural Computational Unit at the Okinawa Institute of Science was able to establish three different types of depression, which are fundamentally different. According to the researchers, the three different subtypes are largely determined by two factors. On the one hand through certain functional connection patterns between the brain regions and on the other hand through traumatic childhood experiences. Common antidepressants have no effect in one of the three forms. The study results were recently published in the scientific reports.
Depression can have different bases
Selective serotonin reuptake inhibitors (SSRIs) are the most commonly prescribed depression medications that work in many patients. However, these medications do not have the same effect in all people and in some cases the depression does not improve even after ingestion. "It has always been speculated that different types of depression exist and that they influence the effectiveness of the drug," reports Prof. Kenji Doya in a press release on the study results.
Course of the study
In their study, the researchers examined the brains of the participants. A total of brain activity patterns in 78 different regions of the brain were analyzed using magnetic resonance imaging. In addition, the blood was examined and the test subjects had to fill out questionnaires and be asked about sleeping habits, stress problems and other mental illnesses.
How do the forms of depression differ?
Three different forms of a depressive illness emerged from the research. "This is the first study to identify depression subtypes from both life history and MRI data," said Doya. Here is an overview of the types of depression:
- Type D1: This type of depression is characterized by a high functional connectivity of the brain. Especially brain regions, which are responsible for the processing of language and numbers, spatial perception and attention, show a high connectivity. In addition, those affected have a history of childhood trauma.
- Type D2: This subtype is characterized by a high functional connectivity of the brain, but there are no traumatic childhood experiences.
- Type D3: With this form, only a low functional connectivity of the brain was found and those affected had no traumatic childhood experiences.
For which depressions do medications have no effect
According to the research group, the patient group, which both suffered from traumatization in childhood and showed higher brain region connectivity (type D1), suppressed depression. SSRI drugs were ineffective. In contrast, the other two groups tended to respond positively to the treatment, the Japanese scientists report.
New treatment techniques are needed
As the researchers emphasize, the study points to the need to research and establish new treatment techniques. New therapies would have to be created, especially for those with D1 depression. “Our study offers a promising direction for scientists studying neurobiological aspects of depression to continue their research,” summarizes Professor Doya. (vb)