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HomeA Practitioner's Must ReadLong-lasting mental health is 'not normal' - New Zealand study

Long-lasting mental health is 'not normal' – New Zealand study

A small, poorly understood segment of the population stays mentally healthy from age 11 to 38,  a Duke University longitudinal study of New Zealanders concluded. Everyone else encountered either temporary or long-lasting mental disorders, with 41% experiencing one or more mental disorders that lasted several years or more.

Only 171 of 988 participants, or 17%, experienced no anxiety disorders, depression or other mental ailments from late childhood to middle age, researchers report. Of the rest, half experienced a transient mental disorder, typically just a single bout of depression, anxiety or substance abuse by middle age.

“For many, an episode of mental disorder is like influenza, bronchitis, kidney stones, a broken bone or other highly prevalent conditions,” says study coauthor Jonathan Schaefer, a psychologist at Duke University. “Sufferers experience impaired functioning, many seek medical care, but most recover.”

The remaining 408 individuals (41%) experienced one or more mental disorders that lasted several years or more. Their diagnoses included more severe conditions such as bipolar and psychotic disorders.

Researchers analysed data for individuals born between April 1972 and March 1973 in Dunedin, New Zealand. Each participant’s general health and behavior were assessed 13 times from birth to age 38. Eight mental health assessments occurred from age 11 to 38.

Surprisingly, those who experienced lasting mental health did not display several characteristics previously linked to a lower likelihood of developing mental disorders. Those attributes consist of growing up in unusually affluent families, enjoying especially sound physical health and scoring exceptionally high on intelligence tests.

Instead, mentally healthy participants tended to possess advantageous personality traits starting in childhood, Schaefer and colleagues found. These participants rarely expressed strongly negative emotions, had lots of friends and displayed superior self-control. Kiwis with rock-solid mental health also had fewer first- and second-degree relatives with mental disorders compared with their peers.

As adults, participants with enduring mental health reported, on average, more education, better jobs, higher-quality relationships and more satisfaction with their lives than their peers did. But lasting mental health doesn’t guarantee an exceptional sense of well-being, Schaefer says. Nearly one-quarter of never-diagnosed individuals scored below the entire sample’s average score for life satisfaction.

Less surprising was the 83% overall prevalence rate for mental disorders. That coincides with recent estimates from four other long-term projects. In those investigations – two in the US, one in Switzerland and another in New Zealand – between 61% and 85% of participants developed mental disorders over 12- to 30-year spans.

Comparably high rates of emotional disorders were reported in 1962 for randomly selected Manhattan residents. Many researchers doubted those findings, which relied on a diagnostic system that was less strict than the three versions of psychiatry’s diagnostic manual that were introduced and used to evaluate New Zealand participants as they got older, says psychiatric epidemiologist William Eaton of Johns Hopkins Bloomberg School of Public Health. But the Manhattan study appears to have been on the right track, Eaton says.

Increased awareness that most people will eventually develop a mental disorder at least briefly, can reduce stigma attached to these conditions, he suspects.

Psychiatric epidemiologist Ronald Kessler suspects the numbers of people experiencing a mental disorder may be even higher than reported. Many participants deemed to have enduring mental health likely developed brief mental disorders that got overlooked, such as a couple of weeks of serious depression after a romantic breakup, says Kessler of Harvard Medical School, who directs US surveys of mental disorders. Rather than focusing on rare cases of lasting mental health, “the more interesting thing is to compare people with persistent mental illness to those with temporary disorders,” he says.

Abstract
We review epidemiological evidence indicating that most people will develop a diagnosable mental disorder, suggesting that only a minority experience enduring mental health. This minority has received little empirical study, leaving the prevalence and predictors of enduring mental health unknown. We turn to the population-representative Dunedin cohort, followed from birth to midlife, to compare people never-diagnosed with mental disorder (N = 171; 17% prevalence) to those diagnosed at 1–2 study waves, the cohort mode (N = 409). Surprisingly, compared to this modal group, never-diagnosed Study members were not born into unusually well-to-do families, nor did their enduring mental health follow markedly sound physical health, or unusually high intelligence. Instead, they tended to have an advantageous temperament/personality style, and negligible family history of mental disorder. As adults, they report superior educational and occupational attainment, greater life satisfaction, and higher-quality relationships. Our findings draw attention to “enduring mental health” as a revealing psychological phenotype and suggest it deserves further study.

Authors
Schaefer, Jonathan D; Caspi, Avshalom; Belsky, Daniel W; Harrington, Honalee; Houts, Renate; Horwood, L John; Hussong, Andrea; Ramrakha, Sandhya; Poulton, Richie; Moffitt, Terrie E

[link url="https://www.sciencenews.org/article/long-lasting-mental-health-isnt-normal"]Science News report[/link]
[link url="http://psycnet.apa.org/psycinfo/2016-58119-001/"]Journal of Abnormal Psychology abstract[/link]

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