Psychiatric diagnoses are too often inaccurate

A genome-wide study shows for the first time that differing traumata in patients with Posttraumatic Stress Disorder have different effects on the biology of the disease

So far, mental disorders have usually been treated according to the principle that patients with the same diagnosis and the same symptoms received the same treatment. A new study by an international team of researchers led by scientists of the Max Planck Institute of Psychiatry suggests that this concept has to be reconsidered: The same diagnosis doesn‘t automatically imply the same treatment.

For the first time, a genome-wide study in patients suffering from posttraumatic stress disorder (PTSD) has succeeded in showing the distinct influence of different traumata on the biology of the disease. Thus, at the level of gene regulation and epigenetics, it is not foremost the diagnosed symptoms that are decisive for the biology of a patient but the so-called environmental risk factors - such as point in time, duration, intensity or kind of a trauma suffered by a person. The long time unanswered question whether biological changes in anxiety disorders like PTSD reflect these individual environmental factors or not could hence be answered for the first time.

The influences of environmental factors were examined by looking exemplarily at the effects of childhood-maltreatment and abuse of patients suffering from PTBS. The researchers analyzed peripheral blood cells of 169 male and female persons with an average age of 45 years and compared them. All persons were severely traumatized and came from the City of Atlanta, Georgia. According to their anamnesis, they were divided into three groups: one group with patients who were traumatized but not suffering from PTSD, as well as two other groups with patients all showing symptoms of PTSD that were distinguished in whether they reported on abuse and maltreatment in childhood or not.

In order to express the changes in gene regulation, the researchers studied mRNA-transcripts – short single-stranded copies of the DNA sequence encoding information for the production of proteins and enzymes. Furthermore, the long-lasting changes in the DNA, the so-called DNA methylations, which are one kind of epigenetic regulation of the metabolism of each cell, were measured. Surprisingly, the two PTSD groups showed, in comparison to the control group, completely different and non-overlapping molecular patterns. Only 2 % of the transcripts were altered the same way in both groups. The remaining transcripts were altered specifically, depending on whether the person had suffered from maltreatment during the childhood or not.

„It seems that patients with the same diagnosis and the same symptoms but different environmental conditions show clearly measurable differences,“ explains Divya Mehta, first author of the study. „This is also shown at the level of epigenetic marks which are found in their scope 12 times as often in the group with maltreatment during the childhood.“

„The results confirm our suspicion that the biology of psychiatric disorders is more complex than previously often assumed,“ Elisabeth Binder, head of the study, comments. „Traumatic events happening in early childhood engrave themselves in the cell over a long period of time. It seems it is not only the disease itself that plays an important role in the biology of anxiety disorders and depression, but all our experiences before the onset of the disease“. This should be taken into account for the treatment of anxiety disorders and depression, Binder emphasizes.

For the future development of biomarkers, the outcome of the study represents an important step forward, says first author Mehta: „It gives us a better understanding of the risk factors of psychiatric diseases and helps us to develop individual strategies for diagnosis and treatment.“

MG