Why Does It Seem Like Everyone Has More Than One Mental Illness?

Today, it seems more common than not to receive multiple mental health condition diagnoses, or comorbidities. In fact, research shows more than half of people that receive one psychiatric disorder diagnosis will receive a second or third diagnosis in their lifetime, while about a third will receive four or more.

We know about many factors that can contribute to a mental health diagnosis, but what about genetics? A recent study focused on the genetic analysis of some of the most common psychiatric conditions found that many disorders actually share a common genetic makeup.

The Research

Researchers from the University of Texas at Austin, Vrije Universiteit Amsterdam and other collaborating institutions analyzed the genetic makeup of eleven major psychiatric conditions, including bipolar disorder, post-traumatic stress disorder, major depressive disorder, anxiety disorder, schizophrenia, anorexia nervosa, obsessive-compulsive disorder, ADHD, Tourette's syndrome, problematic alcohol use, and autism.

They were able to do so using data from hundreds of thousands of individuals that submitted genetic material to large-scale datasets.

The results revealed a shared genetic architecture between anorexia nervosa and obsessive compulsive disorder, as well as genetic overlap between anxiety disorder and major depressive disorder.

The findings identified 152 genetic variants shared across multiple disorders, but it's still unknown exactly what the genes do. Researchers hope this could be a step toward changing the way diagnoses are administered and eventually lead to treatments that address multiple psychiatric conditions at once, rather than piecemeal.

"If you had a cold, you wouldn't want to be diagnosed with coughing disorder, sneezing disorder, and aching joints disorder," said lead study author Andrew Grotzinger in a statement. "This study is a stepping stone toward creating a diagnostic manual that better maps on to what is actually happening biologically."

Clinical psychologist Jacquelyn Flood, PsyD, clinical director of psychology at Elemy, points out that genetic research like this could be especially helpful in diagnosing conditions in children, as symptoms can differ from those experienced by adults.

"Depression can look like anger or irritability in a child, or PTSD could look like acting out," Flood says. "If a teen or child struggles to develop rapport with their psychologist and their parents can’t describe what’s happening, genetics could help identify the problem more quickly."

The Challenges of Polypharmacy

Data from health care commercial intelligence service Definitive Healthcare shows the total number of mental, behavioral and neurodevelopmental diagnoses increased by 30% between 2018 and 2021. And total prescription claims for mental health-related drug classes increased by about 14% each year between 2017 and 2020.

Meanwhile, the prevalence of psychiatric polypharmacy, or the prescription of two or more psychiatric medications to a patient at the same time, varies between 13-90%. It presents challenges for both patients and practitioners. Research has shown that "low levels of literacy and high levels of material disadvantage, which are common among public mental health service users, make managing and understanding multiple medications more difficult."

For healthcare professionals, it's common for a team of physicians to work together in determining the appropriate treatment for comorbidities, so it's important that an individual's doctors are aware of all medications and over-the-counter treatments they're taking. Many medications can have negative side effects when taken together.

Because polypharmacy can be necessary and justified for certain patients, physicians are advised to approach prescribing multiple medications using the acronym SAIL.

S: Keep drug regimen Simple

A: know drug Adverse effects

I: The prescribed drug should have a clear Indication

L: keep List of drug name and dosage in patient's chart

and TIDE:

T: Allow Time to address medication issues

I: understand Individual variability

D: avoid potential dangerous Drug-drug interactions

E: Educate patients regarding treatment.

"Today, diagnostics requires a lot of investigation," Flood says. "Once I’ve gathered all of this information, I can recommend treatment—but I have to jump through a lot of hoops to eventually get there."

As genetic research like this continues to advance, managing medications and finding the most effective and streamlined treatment regimen could become much easier.