Neuroscience News: Multiple Diagnoses Are the Norm With Mental Illness and a New Genetic Study Explains Why

"More than half of people diagnosed with one psychiatric disorder will be diagnosed with a second or third in their lifetime. About a third have four or more.

This can make treatment challenging and leave patients feeling unlucky and discouraged.

But a sweeping new analysis of 11 major psychiatric disorders offers new insight into why comorbidities are the norm, rather than the exception, when it comes to mental illness.

The study, published this week in the journal Nature Genetics, found that while there is no gene or set of genes underlying risk for all of them, subsets of disorders—including bipolar disorder and schizophrenia; anorexia nervosa and obsessive-compulsive disorder; and major depression and anxiety—do share a common genetic architecture.

The finding could ultimately open the door to treatments that address multiple psychiatric disorders at once and help reshape the way diagnoses are given, he [Andrew Grotzinger] said.

How the study worked

For the study, Grotzinger and colleagues at University of Texas at Austin, Vrije Universiteit Amsterdam and other collaborating institutions analyzed publicly available genome-wide association (GWAS) data from hundreds of thousands of people who submitted genetic material to large-scale datasets, such as the UK Biobank and the Psychiatric Genomics Consortium.

They looked at genes associated with 11 disorders, including: schizophrenia, bipolar disorder, major depressive disorder, anxiety disorder, anorexia nervosa, obsessive-compulsive disorder, Tourette syndrome, post-traumatic stress disorder, problematic alcohol use, ADHD and autism.

Linked diagnoses

They found 70% of the genetic signal associated with schizophrenia is also associated with bipolar disorder. That finding was surprising as, under current diagnostic guidelines, clinicians typically will not diagnose an individual with both.

They also found anorexia nervosa and obsessive-compulsive disorder have a strong, shared genetic architecture, and that people with a genetic predisposition to have a smaller body type or low BMI (body mass index), also tend to have a genetic predisposition to these disorders.

Not surprisingly, as the two diagnoses often go together, the study found a large genetic overlap between anxiety disorder and major depressive disorder.

When analyzing accelerometer data, the researchers found disorders that tend to cluster together also tend to share genes that influence how and when we move around during the day.

For instance, those with internalizing disorders, such as anxiety and depression, tend to have a genetic architecture associated with low movement throughout the day.

Compulsive disorders (OCD, anorexia) tend to correlate with genes associated with higher movement throughout the day, and psychotic disorders (schizophrenia and bipolar disorder) tend to genetically correlate with excess movement in the early morning hours.

In all, the study identifies 152 genetic variants shared across multiple disorders, including those already known to influence certain types of brain cells."

*I think that the fact we are starting to understand more in-depth of the "genetic architecture" is incredible! I love genetics and I honestly believe that we don't know everything there is to know yet. I would hope that each mental illness is caused by a specific gene or genes and we just haven't found it yet, but who knows. I think this study is so cool and it's exciting to see where this will lead to! It will help many people who struggle with more than one mental illness by hopefully creating just one medication/treatment to treat both comorbidities instead of multiple at the same time.*

What do you think of this study? How do you think these findings will help the field of psychiatry?

#Genetics #Psychiatry #MentalIllness

Read the full article here!