By In recent years, scientists have been working hard to understand the biological mechanisms of mental disorders in order to achieve more precise and personalized treatments. What do we know today?
Researchers have been studying the role of genetics in mental health for decades . Specifically, they are looking for clues that might explain a connection between a person’s genetic makeup and the mental disorders they may suffer from. However, the results have often been confusing, inaccurate or imprecise. In fact, we still lack biomarkers that indicate the presence of a mental disorder.
A biomarker is the result of a medical test, such as a blood test or a neuroimaging test, that unequivocally tells us that we have, for example, depression or social anxiety. For narcolepsy, orexin is the only known biomarker. However, a recent study attempts to shed more light on this field.
Precision psychiatry?
Compared to the healthy population, people with psychiatric problems live approximately a decade less . This is one of the factors that is motivating research that attempts to clarify the role played by genetics in the etiology of psychopathology, in order to produce more precise, effective and safe pharmacological treatments.
Furthermore, it is well known that pharmacotherapy , rather than a curative intervention, is palliative (Andreassen, 2023). This is explained by the relapses and worsening of symptoms that patients often experience. Thus, it is very necessary for psychiatry to correct the above. Its aim is to abandon the current diagnosis, through clinical observation, in favour of diagnosis through medical tests.
“There have been no major therapeutic advances in psychiatry in recent decades.”
-Ole A. Andreassen-
Current knowledge on the relationship between genetics and mental disorders
The fact that there are clinical entities that are inherited to a greater or lesser extent is a certainty supported by science . The debate about whether mental disorders are inherited or learned is obsolete.
For this reason, what is currently known is that both things occur at the same time and interact with each other. The interaction between genes and the context that surrounds us is called epigenetics.
What is epigenetics?
People have a set of genes from the moment they are conceived. These genes, however, can be activated or remain dormant. In many cases, their activation is determined by the environment in which they live.
So if we have a gene that is designed to “wake up” in a context, if this context were to appear, the gene would be activated. But if this context never occurs, the gene will remain “asleep.”
On the other hand, it is known that “chaotic factors” can also play a role in the origin of mental illness. These factors refer to variations and alterations in DNA that, despite not being inherited, accumulate in nervous tissue as a person grows and ages, influencing the onset of the disease.
“Identifying genetic risk variants could provide valuable insights into their etiology by pinpointing central biological mechanisms.”
-Ole. A. Andreassen-
Current state of the art: how heritable are mental disorders?
In the research that we are showing you today, we have compiled all the information available on the degree of heritability of the different psychiatric pathologies.
For example, the heritability or genetic risk for psychosis spectrum disorders such as schizophrenia and neurodevelopmental disorders such as autism has been found to be as high as 85%. That is, the risk of suffering from these clinical entities, as a first-degree relative, is 85%.
In contrast, for depression and anxiety, heritability can reach almost 60%. What explains why some disorders are more heritable than others? The answer can be found in the environment. While for schizophrenia, 85% of the risk is genetic, for depression , 40% of the risk is environmental.
“There is no single disease gene for psychiatric disorders, but thousands of genetic variants that act together and collectively influence disease risk.”
-Ole A. Andreassen-
That is, if we have a heritability of 60%, this means that 60% potentially corresponds to the genes activated at the current time, while the remaining 40% corresponds to the environment. This is how epigenetics would potentially act.
The highest heritability is found for schizophrenic disorder, bipolar disorder, and ADHD; whereas depression, Tourette syndrome, and PTSD have lower heritability, in comparison.
A “genetic dance”
One of the conclusions of genetic psychiatry is that mental pathologies are far from depending on a single gene. In fact, there is talk of thousands of genes acting together and reacting to contextual influences to produce, consequently, a clinical entity in each person.
However, we still lack sufficient knowledge to create a more precise and curative psychiatry. Genetic psychiatry is still a very young branch and is just taking its first steps. A certain level of scientific evidence has been found that there are variants of different genes that have an intense influence on various disorders.
The next step is to better understand what they are and how they act. Therefore, the work that remains ahead is very important.
«Psychiatric genetics is still in its early stages, but it promises to improve mental health care by paving the way for precision psychiatry.»
-Ole. A. Andreassen-