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 a step closer to deciphering this puzzle. The researchers were able to break down the depression in three different forms. Medicines have no effect in any of these forms.
A team from the Neural Computational Unit of the Okinawa Institute of Science has identified three 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 areas and on the other by traumatic experiences from childhood. Normal antidepressants have no effect in any of the three forms. The study results have recently been published in the scientific journal "Scientific Reports".
Depression can have different bases
Selective serotonin reuptake inhibitors (SSRIs) are the most commonly prescribed antidepressant medication that affects many patients. However, these drugs do not work in the same way in all people and in some people the depression does not improve after taking it. "It has always been speculated that there are different types of depression and that they influence the effectiveness of the drug," says Prof. dr. Kenji Doya in a press release about the study results.
Course of the study
In their research, the researchers examined the brains of the participants. In total, brain activity patterns in 78 different brain regions were analyzed using magnetic resonance imaging. In addition, the blood was examined and the subjects had to complete questionnaires and were asked to solve sleeping habits, stress problems and other mental illnesses.
How do the forms of depression differ?
Three different forms of depressive disorders emerged from the study. "This is the first study to identify depression subtypes from both 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 areas that are responsible for processing speech and numbers, spatial perception and attention have high connectivity. Moreover, those affected have a history of trauma from childhood.
- Type D2: This subtype is characterized by a high functional connectivity of the brain, but traumatic experiences from childhood are not present.
- Type D3: In this form only a small functional connectivity of the brain could be detected and the victims had no traumatic experiences from childhood.
Where depressants have no effect on
According to the research group, the group of patients with both childhood trauma and higher brain region connectivity (type D1) had depression suppression. SSRI drugs were not effective. 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 research points to the need to investigate and establish new treatment techniques. Especially for people with depression D1, new therapies should be made. "Our study provides a promising direction for scientists studying the neurobiological aspects of depression to continue their research," Professor Doya concludes. (Vb)