Three different forms of depression identified

Study: The three subtypes of depression

The exact causes of depression are not yet known, although nearly 300 million people worldwide suffer from this mental illness. A Japanese research team is close to deciphering this puzzle. Researchers have been able to break down depression into three different forms. In one of these forms, the drugs show no effect.

A team from the Neural Calculation Unit of the Okinawa Institute of Sciences has established three fundamentally different types of depression. According to the researchers, the three subtypes are largely determined by two factors. On the one hand, by some types of functional connections between brain regions and, on the other hand, by traumatic experiences of childhood. In one of three forms, the current antidepressants show no effect. The results of the study were recently published in the scientific journal "Scientific Reports".

Depression can have different bases

Selective serotonin reuptake inhibitors (SSRIs) are the most commonly prescribed drug for depression and affect many patients. However, these drugs do not work the same way in all people and in some people, depression does not improve after taking them. "It has always been badumed that different types of depression existed and that they affected the effectiveness of the drug," says Professor Kenji Doya in a press release about the results of the study.

Course of the study

In their study, the researchers examined the participants' brains. In total, patterns of brain activity in 78 different regions of the brain were badyzed using magnetic resonance imaging. In addition, the blood was examined and subjects had to complete questionnaires and be asked for sleep patterns, stress problems and other mental illnesses.

How are the forms of depression different?

From research, three different forms of depressive illness have emerged. "This is the first study to identify subtypes of depression from life history and MRI data," Doya explains. 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 speech and number processing, 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 the traumatic experiences of childhood are not present.
• Type D3In this form, only a small functional connectivity of the brain could be detected and the affected people had no traumatic experience during their childhood.

In which drugs against depression show no effect

According to the research group, the group of patients experiencing both childhood trauma and higher connectivity between brain regions (type D1) presented with depression. SSRI drugs were ineffective. In contrast, Japanese scientists reported that the other two groups tended to respond positively to treatment.

New treatment techniques are needed

As the researchers point out, the study highlights the need to explore and establish new treatment techniques. New therapies should be created, especially for people with D1 depression. "Our study provides scientists who are studying the neurobiological aspects of depression with a promising direction for further research," concludes Professor Doya. (Vb)