3 different types of depression decrypted- In one, drugs are ineffective

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 Japanese research team has come one step closer to deciphering this puzzle. The researchers were able to break down the depression into three different forms. In one of these forms, drugs show no effect.

A team from the Neural Computational Unit at the Okinawa Institute of Science has been able to establish three different types of depression that are fundamentally different. According to the researchers, the three different subtypes are largely determined by two factors. On the one hand by certain functional connection patterns between the brain regions and on the other hand by traumatic childhood experiences. In one of the three forms, common antidepressants have no effect. The study results have recently been published in the scientific journal "Scientific Reports".

A Japanese research team was the first to show a division of depression into three subtypes. In one form of depression, common antidepressants were ineffective. (Image: FotoLyriX / fotolia.com)

Depression can have different bases

Selective serotonin reuptake inhibitors (SSRIs) are the most commonly prescribed medication for depression that affects many patients. However, these medications do not work the same way in all people and in some people depression does not improve after taking them. "It has always been speculated that different types of depression exist and that they affect the effectiveness of the drug," says 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. In total, brain activity patterns in 78 different regions of the brain were analyzed using magnetic resonance imaging. In addition, the blood was examined and the subjects had to complete questionnaires and be asked to sleep habits, stress problems and other mental illnesses.

How do the forms of depression differ??

From the research, three different forms of depressive illness emerged. "This is the first study to identify depression subtypes from both life history and MRI data," explains Doya. Here are the types of depression at a glance:

• Type D1: This type of depression is characterized by a high functional connectivity of the brain. In particular, brain regions responsible for processing speech and numbers, spatial perception, and attention have 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 traumatic childhood experiences are not available.
• Type D3: In this form, only a small functional connectivity of the brain could be detected and those affected had no traumatic childhood experiences.

In which depression drugs show no effect

According to the research group, the group of patients experiencing both childhood trauma and higher brain-region connectivity (type D1) had depression suppression. SSRI drugs were ineffective. In contrast, the other two groups tended to respond positively to treatment, the Japanese scientists report.

New treatment techniques are needed

As the researchers emphasize, the study points to the need to explore and establish new treatment techniques. Especially for those with D1 depression new therapies would have to be created. "Our study offers a promising direction for researchers studying the neurobiological aspects of depression to continue their research," concludes Professor Doya. (Vb)