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Mental Illness Is Far More "Normal" Than We Think

Almost everyone you know will face a mental health challenge in their lifetime.

Key points

  • The lifetime prevalence of mental health conditions is much higher than previously believed.
  • Most people's mental health challenges will be temporary.
  • Understanding the rates of mental illness can lower the stigma around these conditions.
Beautiful landscape/Shutterestock
Source: Beautiful landscape/Shutterestock

I used to teach a course in “abnormal psychology,” and students were often amazed by the high rates of mental illness. The best studies at that time (around 2015) were based on large, randomly selected cross-sections of the population. The study designs were retrospective—literally “looking backward”—as the research interviewers asked participants a series of detailed questions about their entire mental health history.

Pathologizing Sadness?

The numbers that emerged from these retrospective reports shocked many people. About a third of the sample had experienced a mental health condition in the past twelve months, and nearly half had at some point in their lifetime. Many of my students wondered if the threshold for diagnoses were too low—after all, shouldn’t “abnormal” psychology be relatively rare? It was easy to wonder if the boundaries of mental illness were being stretched to include relatively mild experiences of difficult emotions.

I recently discussed these issues on the Think Act Be podcast with Dr. Jonathan Schaefer, a clinical psychologist and research scientist at the University of Minnesota. Are we pathologizing everyday sadness and anxiety? Schaefer doesn’t think so.

“I don’t buy the argument that if lifetime prevalence is high for mental disorders, it must mean we’re medicalizing normality,” he said. “We don’t apply that kind of logic to physical health problems.” He used the example of a common illness like the flu. “Lots of people will get the flu,” Schaefer explained, “but that doesn’t mean that diagnosing and treating that condition is ‘medicalizing normality.’”

Uninterrupted Mental Health Isn’t Normal

Schaefer is on firm ground when he compares common mental health conditions like depression to physical ailments like the flu. He and his colleagues have shown that results from previous studies were almost certainly underestimates of the lifetime prevalence of mental illness. The actual number is closer to 83 percent; a full five out of six people in Schaefer’s research met the criteria for a mental health diagnosis by age 38. (Schaefer and I are both among the 83 percent.)

Schaefer’s data come from an ongoing longitudinal cohort study in Dunedin, New Zealand. Researchers have been following about 1000 participants since birth, and administering repeated psychiatric assessments. The most common conditions in the Dunedin sample were anxiety disorders (58 percent of the sample), major depression (48 percent), and substance abuse or dependence (41 percent).

Why had retrospective studies undercounted mental illness? Schaefer blamed it on “recall failure”: Participants simply forgot that they had had a certain condition. With serious physical health conditions, like heart disease or diabetes, we’ll almost certainly remember our diagnosis. But for mental health conditions, “we know that recall failure happens incredibly frequently,” said Schaefer.

He attributes forgetting to state-dependent memory. “People tend to view their past experiences through the lens of their present circumstances,” he explained. If we’re in a good mood, it’s harder to remember the times when we were feeling down, and we’re likely to think they weren’t as bad as they actually were.

Schaefer and colleagues’ longitudinal cohort study, in contrast, minimized the threat of recall failure, since participants needed to remember only the year since the last assessment and not their entire life history.

State vs. Lifetime History

Schaefer’s study was published in the Journal of Abnormal Psychology, which struck me as a bit ironic, given how normal it is to experience a mental health condition at some point in one’s life. But Schaefer clearly distinguishes between what’s normal for a lifetime and what’s normal for our day-to-day experience.

“It’s important to think about the lens we’re adopting, and whether we’re looking across lifespans or within lifespans,” he explained. “When we’re talking about what is ‘normal,’ this is a lifetime perspective. It’s saying that the average life has at least one period of diagnosable mental illness in it.” From that perspective, mental illness is a very normal experience.

“But you can also look within a person’s life across people,” he continued, “and say that the average mental health state for people is to not be in a state of diagnosable disorder.” We apply the same way of thinking to physical health conditions, since “the average state of health for most human beings is to not be experiencing a cold or the flu.” Thankfully the mental health struggles that most of us face will be temporary—“sort of like wave,” as Schaefer described them. “They surge, they crest, and then for most people they recede.”

Transcending Stigma

The impulse to set a high threshold for what we call “mental illness” actually may betray a pernicious form of stigma. It’s easier to see mental illness as something that happens to “those people” if it’s relatively rare. Conversely, the actual numbers suggest that going through a major mental and emotional challenge is typical of the human experience. Thankfully the work that Schaefer and others are doing has direct relevance to the dehumanizing stigma that continues to surround psychiatric illness.

“You can think of pretty much any successful person you really admire,” said Schaefer, “and the odds are pretty good that they probably had a significant mental health problem at some point. That in and of itself is very reassuring and normalizing—and helps you realize you’re not alone.”

That message can start early, with what we teach young people about mental health. “The main message for parents is one that emphasizes appropriate socialization around mental health problems, and early intervention,” Schaefer said. “Normalize talking about emotions and mental health. And make sure your kids know it’s perfectly acceptable to go to therapy.”

We can also provide kids and teens with the tools they’ll need for managing mental health challenges—especially with the additional challenges brought about by COVID-related isolation. “Help them to cultivate the coping skills, the self-talk, and the daily routines that other areas of science have shown contribute to psychological resilience,” Schaefer advised, such as the research-backed practices of cognitive behavioral therapy (CBT).

We can also instruct young people about what to expect for their loved ones. “Prepare them for the fact that their friends and their future partners will probably have some of these issues,” said Schaefer—“and that’s okay. Most of the time they’re temporary, and they happen to almost everyone.”

So if you or someone you love has struggled with mental illness, take heart, says Schaefer: “You are in great company.”

The full conversation with Dr. Jonathan Schaefer is available here: “How Better Mental Health Epidemiology Can Lower Stigma."

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Kessler, R. C., Berglund, P., Demler, O., Jin, R., Merikangas, K. R., & Walters, E. E. (2005). Lifetime prevalence and age-of-onset distributions of DSM-IV disorders in the National Comorbidity Survey Replication. Archives of General Psychiatry, 62, 593-602.

Schaefer, J. D., Caspi, A., Belsky, D. W., Harrington, H., Houts, R., Horwood, L. J., ... & Moffitt, T. E. (2017). Enduring mental health: Prevalence and prediction. Journal of Abnormal Psychology, 126, 212-224.

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