Using symptom dimensions may provide more precise, personalized mental health care

A researcher from the University of Kansas has led a large-scale study of university undergraduates to better understand how psychological conditions such as depression, anxiety, post-traumatic stress disorder and eating disorders are connected.

The investigation, appearing in the Journal of Psychopathology and Clinical Science, relied on the Hierarchical Taxonomy of Psychopathology (HiTOP), an emerging alternative to the Diagnostic and Statistical Manual of Mental Disorders (DSM), the traditional guide for diagnosing and treating patients.

The findings suggest HiTOP's use of symptom dimensions may better support more precise, personalized mental health care.

There are problems with the way we diagnose people with mental health issues. The current system is categorical, so you either have the mental health condition, or you don't. That can be really problematic for a number of reasons, and it's especially true for eating disorders."

Kelsie Forbush, lead author, professor of clinical child psychology at KU

Forbush also pointed to concerns with the DSM, which is currently recommended by the American Psychological Association, including a tendency for disorders to be highly heterogeneous.

"There are numerous ways a person could meet criteria for a category," Forbush said. "I believe there are 126 different ways a person could meet criteria for anorexia nervosa. So, in many cases, that yes-or-no label doesn't really tell the clinician or therapist what is actually going on with a person. It's also possible for somebody with anorexia nervosa and bulimia nervosa to have the exact same symptoms in common, except for being at different body weights."

Forbush said two clients can have completely different diagnostic labels but nearly identical symptoms. Under the DSM, she added, two people can also be assigned the same label with little symptom overlap.

"We also see an issue of diagnostic migration over time because of some of these issues," Forbush said. "For example, we did a study several years ago where we found among people who were diagnosed with anorexia nervosa at baseline, one year later none of them had the same diagnosis of anorexia nervosa, but they all had an eating disorder."

Under the DSM's diagnostic system, Forbush said, small changes in symptom presentation can lead to a different diagnosis. Because of these issues, HiTOP has gained traction.

"People are wanting a system that is going to be more clinically helpful and also convey more information about prognosis," she said. "That's another issue we have with the current diagnostic system. When I get the label, I don't know: Is this somebody who is at high risk or low risk? It's just not very informative in that way."

Alternatively, HiTOP uses dimensional systems rather than diagnostic categories. More specific subdimensions - such as fear, distress and eating pathology - are grouped under broader dimensions.

"These are dimensions instead of categories," Forbush said. "One way I think of it is if you get your blood pressure taken or your weight taken, it's a number anywhere along a range. And you can also say, 'Oh, that's high blood pressure,' or 'that's a weight that the CDC would say is obesity,' right?"

Using HiTOP, Forbush and her collaborators are developing a hierarchy of symptoms and relationships among symptoms to better understand what a person is experiencing.

"In our past research, we found that this dimensional system was much more predictive of things like whether somebody recovered, their psychiatric impairment, and how severe their mental health condition was even a year later," Forbush said. "Whereas the current system, the DSM, didn't predict very much, even when we looked at many disorders together."

The study used data from a nationally representative sample of veterans that was collected at KU. All participants were veterans who had separated from their service branch within the previous six months.

The team analyzed how symptoms clustered together and identified "internalizing" as a broad, higher-order dimension reflecting a tendency toward inwardly directed distress. This hierarchical internalizing structure supports HiTOP over DSM-style diagnostic categories.

"I'd say the core of internalizing is a high propensity toward negative emotionality," Forbush said. "So high levels of neuroticism - more likely to feel sad, down, anxious, just wired that way. Even negative temperament: some babies come out with a more negative temperament than others. That doesn't mean they'll develop disorders, but it makes it more likely. So it's really about treating that core negative emotionality. If that is treated well, the hope is people won't develop more disorders within that domain over time."