When we hear about the number of people who struggle with psychiatric disorders, the most common quote is 1 in 5 for any given year. This statistic comes from several reports over the years issued by the Surgeon General’s office and the Substance Abuse and Mental Health Services Administration (SAMSA). 

To critics, this number seems unbelievably high. A new study, however, is sure to fuel this controversy further. The research comes from one of the most famous long-term mental health studies ever done. The Dunedin Study has followed slightly more than 1,000 individuals from New Zealand for 35 years, starting when subjects were only 3 years old. The data from this study have led to a huge number of publications over the years and several news headlines. The goal of this latest effort was to identify the factors that are related to people who have managed to be free of all psychiatric diagnoses during the entire study interval. What was surprising, however, was just how small this group turned out to be.

The 1 in 5 number returns in this study, but now it signifies the number of individuals across a 35-year period who did NOT meet criteria for a psychiatric disorder at any of the multiple assessment points. That’s right, only 17% of their sample qualified for that designation. Far more common was the person who over decades had occasional times when they met criteria for one or two disorders—most commonly anxiety, depression, and substance abuse—which often was temporary.   

Getting back to the original aim of the study, enduring mental health turned out not to be significantly related to some expected factors like economic wealth, good physical health, or even intelligence but rather to certain early temperament and personality factors identified when the subjects were as young as 3 years old such as being more social, less emotionally reactive, and having higher levels of self-control. Not having family members with psychiatric disorders was also predictive.

Writing this, I can already feel the eye rolling and hear the negative reactions by some to this study. Much of the concern will likely surround medication overuse and/or the stigma that would be predicted to follow the increased number of individuals with a diagnosed psychiatric condition. Both are clearly important issues deserving of some comment. Regarding medications, the study did not go into details about their sample, but the text clearly gives the impression that medications were not overly common, with many people reporting their episodes of depression or anxiety as something which resolved without pharmacological support. Even allowing for the somewhat fuzzy logic that we should deny the existence of a medical problem because we don’t like the way it’s treated, there is reason to be optimistic that the use of psychiatric medications is coming into more balance with other types of interventions and important wellness and health promotion activities.

As far as stigma goes, there is a good argument to be made that a more inclusive perspective of mental illness that actually acknowledges how many of us may have struggled from time to time is far less stigmatizing than a view which restricts psychopathology to an isolated few while the rest of us do everything we can to convince others that there’s “nothing to see here.”

About three years ago, I wrote a Psychology Today post asking “What if We All Got Mentally Ill Sometimes?” In light of these new data and similar studies like it, the question begs asking again. 

At a recent conference, I was looking around the room and noticing what a large percentage of people there were wearing glasses. Thank goodness nobody had convinced them they should just accept their difficulties as “normal” with no intervention needed other than good squint.

@copyright by David Rettew

David Rettew is author of Child Temperament: New Thinking About the Boundary Between Traits and Illness and a child psychiatrist in the psychiatry and pediatrics departments at the University of Vermont College of Medicine.

Follow him at @PediPsych and like PediPsych on Facebook.


Schaefer JD, Caspi A, Belsky DW, et al. (2017).  Enduring mental health:  Prevalence and prediction.  Journal of Abnormal Psychology 126: 212-224.

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