Abnormal is the new normal — at least for mental health. Only a small share of the population stays mentally healthy from age 11 to 38. Everyone else experiences a mental illness at some point, a new study finds.
“For many, an episode of mental disorder is like influenza, bronchitis, kidney stones, a broken bone or other [common] conditions,” says Jonathan Schaefer. He is a psychologist at Duke University. A coauthor of the study, he notes that “Sufferers experience impaired functioning. Many seek medical care, but most recover.”
The study looked at 988 people who lived in New Zealand. Only 171 — or about one in six people —experienced no anxiety disorders, depression or other mental ailments from late childhood to middle age. Of the rest, half experienced a mental disorder that lasted a short time. This was typically just a bout of depression, anxiety or substance abuse. The person then recovered.
The remaining 408 people — roughly two out of every five — experienced one or more mental disorders that lasted at least several years. Their diagnoses included more severe conditions. These may have included bipolar and psychotic disorders.
Schaefer and his colleagues shared their findings in the February Journal of Abnormal Psychology.
By the numbers…
The researchers analyzed data on people born between April 1972 and March 1973 in Dunedin, New Zealand. Each person’s general health and behavior was assessed 13 times from birth to age 38. Mental health was assessed eight times from age 11 onward.
Previous studies had linked several traits with a lower chance of developing mental disorders. These included growing up in an unusually well-off family and enjoying really good physical health. Scoring very high on intelligence tests also has been linked to good mental health. Surprisingly, however, the New Zealanders who stayed mentally healthy scored no better of those qualities than anyone else.
Instead, people with good mental health tended to have personality traits that gave them some sort of advantage. Those traits started emerging in childhood, the surveys showed. These people rarely expressed strongly negative emotions. They also tended to have lots of friends and very good self-control. Those with lasting mental health also had relatively few family members with mental disorders, compared with their peers.
There were some benefits in adulthood for those who always had good mental health. These people had, on average, more education, better jobs and higher-quality relationships. They also reported more satisfaction with their lives than the others did. But lasting mental health doesn’t guarantee an exceptional sense of well-being, Schaefer points out. Nearly one-in-four people never diagnosed with mental illness scored below the entire group’s average score for life satisfaction.
Less surprising was the 83 percent overall rate of mental disorders. That matches recent estimates from four other long-term projects. Two had focused on Americans. One looked at people in Switzerland. The last was another study from New Zealand. These studies followed people for 12 to 30 years. And over that follow-up, between 61 percent and 85 percent of the participants reported having at least some mental disorders.
Such high rates also were reported in an earlier study, from 1962. It had surveyed a random mix of people living on the island of Manhattan in New York City. Many researchers had doubted that study’s findings, however. Why? It had relied on a diagnostic system that was less strict than the ones used to evaluate the people in New Zealand, explains William Eaton. In fact, he says, the Manhattan study now appears to have been on the right track. Eaton is an epidemiologist at the Johns Hopkins Bloomberg School of Public Health in Baltimore, Md.
There is often a stigma attached to mental illness. But if more people realize that most will eventually develop some mental disorder, at least briefly, that stigma might fall, Eaton suspects.
Ronald Kessler is also an epidemiologist. He works at Harvard Medical School in Boston, Mass. Kessler directs U.S. surveys of mental disorders. He suspects the numbers of people who experience a mental disorder may be even higher than what was reported in these studies.
Many people that seemed to have enduring mental health in these studies may not have. They may have developed brief mental disorders that got overlooked, he says. It might have been something such as a couple of weeks of serious depression after a romantic breakup.
Focusing on those rare cases of lasting mental health may not be the best idea, he says. “The more interesting thing is to compare people with persistent mental illness to those with temporary disorders.”
average (in science) A term for the arithmetic mean, which is the sum of a group of numbers that is then divided by the size of the group.
behavior The way a person or other organism acts towards others, or conducts itself.
coauthor One of a group (two or more people) who together had prepared a written work, such as a book, report or research paper. Not all coauthors may have contributed equally.
colleague Someone who works with another; a co-worker or team member.
depression A low spot, such as in a field or the surface of a rock. (in medicine) A mental illness characterized by persistent sadness and apathy. Although these feelings can be triggered by events, such as the death of a loved one or the move to a new city, that isn’t typically considered an “illness” — unless the symptoms are prolonged and harm an individual’s ability to perform normal daily tasks (such as working, sleeping or interacting with others). People suffering from depression often feel they lack the energy needed to get anything done. They may have difficulty concentrating on things or showing an interest in normal events. Many times, these feelings seem to be triggered by nothing; they can appear out of nowhere.
diagnose To analyze clues or symptoms in the search for their cause. The conclusion usually results in a diagnosis — identification of the causal problem or disease.
disorder (in medicine) A condition where the body does not work appropriately, leading to what might be viewed as an illness. This term can sometimes be used interchangeably with disease.
epidemiologist Like health detectives, these researchers figure out what causes a particular illness and how to limit its spread.
influenza (also known as flu) A highly contagious viral infection of the respiratory passages causing fever and severe aching. It often occurs as an epidemic.
journal (in science) A publication in which scientists share their research findings with the public. Some journals publish papers from all fields of science, technology, engineering and math, while others are specific to a single subject. The best journals are peer-reviewed: They send out all submitted articles to outside experts to be read and critiqued. The goal, here, is to prevent the publication of mistakes, fraud or sloppy work.
New Zealand An island nation in the southwest Pacific Ocean, roughly 1,500 kilometers (some 900 miles) east of Australia. Its “mainland” — consisting of a North and South Island — is quite volcanically active. In addition, the country includes many far smaller offshore islands.
peer Someone who is an equal, based on age, education, status, training or some other features.
persistent An adjective for something that is long-lasting.
physical (adj.) A term for things that exist in the real world, as opposed to in memories or the imagination. It can also refer to properties of materials that are due to their size and non-chemical interactions (such as when one block slams with force into another).
psychology (adj. psychological ) The study of the human mind, especially in relation to actions and behavior. To do this, some perform research using animals. Scientists and mental-health professionals who work in this field are known as psychologists.
random Something that occurs haphazardly or without reason, based on no intention or purpose.
stigma A disgrace, source of shame or a stain on one’s reputation — often not justifiably — due to something that one did, experienced or represents to others.
survey (v.) To ask questions that glean data on the opinions, practices (such as dining or sleeping habits), knowledge or skills of a broad range of people. Researchers select the number and types of people questioned in hopes that the answers these individuals give will be representative of others who are their age, belong to the same ethnic group or live in the same region. (n.) The list of questions that will be offered to glean those data.
trait A characteristic feature of something. (in genetics) A quality or characteristic that can be inherited.
Journal: J. Schaefer et al. Enduring mental health: Prevalence and prediction. Journal of Abnormal Psychology. Vol. 126, February 2017. doi:10.1037/abn0000232.
Journal: D. Regier et al. The NIMH Epidemiological Catchment Area Program. Archives of General Psychiatry. Vol. 41, October 1984, p.934. doi:10.1001/archpsych.1984.01690210016003.