Going an extended period of time without being diagnosed with a mental disorder is abnormal, according to a long-term study conducted in New Zealand and two other countries.
“Enduring Mental Health: Prevalence and Prediction,” which was published in The Journal of Abnormal Psychology earlier this month, studied 988 participants in Dunedin, New Zealand, for signs of mental disorders. Of the total study group, only 171 participants, or 17 percent, were found to have gone from late childhood to middle age without having experienced any mental disorders.
“Far from being the aberrant experience of a small, stigmatized subgroup, data from both the Dunedin Study and other longitudinal studies suggest that experiencing a diagnosable mental disorder at some point during the life course is the norm, not the exception,” the study stated.
Researchers from Duke University, King’s College London, the University of North Carolina and the University of Otago analyzed the general health and behavior of individuals born between April 1972 and March 1973 in Dunedin. In order to make a determination during this analysis, the participants were assessed on 13 separate occasions between birth and the age of 38. The participants also had their mental health assessed eight times between the ages of 11 and 38.
Achieving high scores on intelligence tests, being raised in an affluent family and exhibiting good physical health tend to be evident of an individual who enjoys a good state of mental health.
Although many individuals who experience prolonged states of solid mental health tend to display these characteristics, this was not the case in the Dunedin study. Researchers found that lifestyle habits and personality traits developed in an individual’s childhood led to them to have no mental disorders. The 171 participants who did not experience a mental disorder throughout the course of the study were determined to display abnormally high levels of self-control, have many friends and rarely express strong negative emotions.
“In addition, we found that study members with enduring mental health showed significantly higher levels of childhood self-control, in line with previous reports from this cohort demonstrating that higher self-control in childhood predicts other advantageous adult outcomes such as superior physical health, fewer financial problems, less criminal offending, and lower risk of substance dependence,” the study stated.
Researchers subsequently determined that participants who did not develop a mental disorder during the study had fewer close relatives with a diagnosed mental disorder than those who did end up developing a mental disorder.
The benefits of strong mental health are numerous, especially if an individual reaches adulthood without developing a mental disorder. Participants who did not develop a mental disorder were found to have better job opportunities, higher levels of education, higher-quality relationships and more life satisfaction when compared with their fellow study participants that exhibited mental disorders. However, this does not necessarily mean that enduring mental health translates to a sense of well-being. Out of the participants who did not develop a mental disorder, almost 25 percent scored below the entire group’s life satisfaction score.
“For many, an episode of mental disorder is like influenza, bronchitis, kidney stones, a broken bone or other highly prevalent conditions,” said the study’s coauthor Jonathan Schaefer, a psychologist at Duke University. “Sufferers experience impaired functioning, many seek medical care, but most recover.”
The results of the study parallel three similar studies conducted in Christchurch, New Zealand, Oregon, United States and Zurich, Switzerland. In the Zurich study, more than 70 percent of the 591 participants were diagnosed with a mental disorder over the course of 30 years.
In the Christchurch study, approximately 85 percent of the 1,041 participants ended up developing a mental disorder over the span of 20 years. In the Oregon study, more than 70 percent of 816 participants were diagnosed with a mental disorder over the course of 14 years. The results of these related studies prove that the Dunedin study results were not outliers—mental disorders remain the norm despite geographic locations.
The conclusion made in the Dunedin study and the related studies could potentially include understated results, according to Dr. Ronald Kessler, a psychiatric epidemiologist of Harvard Medical School.
Due to the study’s participants having their mental health assessed only eight times in approximately 27 years, it is entirely possible that short-term mental disorders were overlooked by researchers. These brief periods of mental illness could include experiencing severe depression in the wake of a difficult romantic breakup.
Despite the thoroughness of the Dunedin study, additional studies will need to be conducted in order to come to a concrete conclusion. Authors of the Dunedin admit that the study’s weight is limited due to a number of factors, including the fact that nearly all of the participants were white.