Personality and Mental Illness: What's the Link?

IF YOU'RE NEGATIVE NOW, will you be clinically depressed later? Certain personality traits appear more likely to lead to future mental illness, while others seem to protect against it. Emerging research builds a stronger case for this connection between personality and mental health. In particular, a personality trait called neuroticism is associated with conditions like major depression, generalized anxiety and other disorders.

On the other hand, experts say, traits like conscientiousness protect from these disorders. If you're a self-disciplined, dependable type of person, you're less prone to contend with psychiatric conditions. Agreeableness is another trait that carries lower risk.

Neuroticism involves experiencing negative emotions – fear, sadness, guilt, anger, envy – on a regular basis. If you recognize these tendencies in yourself, don't be discouraged. Personalities can change to a certain extent and many people use coping strategies to reduce the impact of negativity on their daily lives and long-term mental health.

It's important to realize that personality traits are a matter of degree, says Dr. Roman Kotov, an associate professor in the department of psychiatry at Stony Brook School of Medicine in New York. They fall on a continuum, just like intelligence.

In 2010, Kotov and colleagues evaluated 175 studies to explore the connection between personality traits and depression, anxiety and substance use disorders. Low levels of extraversion – in other words, introversion – and social phobia were tied to major depressive and anxiety disorders. Disinhibition, which involves impulsiveness and lack of regard for social norms, and disagreeableness were connected to developing substance use disorders. Across the board, neuroticism was the personality pattern most often related to mental health disorders in the review, published in the journal Psychological Bulletin.

A recent study takes the personality-mental illness connection to a whole new level. Genetic variations that influence personality are also tied to the risk of developing mental illness, found researchers led by Chi-Hua Chen, an assistant professor in the department of radiology at the University of California–San Diego.

The innovative study, published last December in Nature Genetics, made use of customer data provided by 23andMe, a personal genetics company, along with data from the European-based Genetics of Personality Consortium, a large collaboration of studies on the human genome and personality associations, and other sources. The 23andMe contribution involved DNA sequencing of genetic data obtained from consumer testing, which was linked to personality scores derived from online survey responses, Chen explains.

The study looked at the "Big Five" categories often used in measuring personality differences. Briefly, by pinpointing precise variations on genes and chromosomes, here's what researchers found for each factor:

Emotional stability: Neuroticism was genetically linked to depression and anxiety disorders.

Extraversion vs. introversion: A genetic connection appeared between extroverted traits – such as being highly active and talkative – and attention deficit hyperactivity disorder, or ADHD.

Openness to experience: This trait includes positive attributes like intellectual curiosity and creativity. However, a link was found to schizophrenia and bipolar disorder.

Agreeableness vs. antagonism: There was less likelihood of a related psychiatric disorder for easy-to-get-along-with personalities.

Conscientiousness vs. unreliability: Traits like diligence and dependability were also tied to a lower risk of developing mental illness.

Compared to physical traits like brain size or height, the genetic influence on personality traits is relatively low, Chen emphasizes. "So even with innate genetic predispositions to tend to be neurotic, life experience can protect you from developing more serious disorders like depression or anxiety," she says.

It's also important to point out that each gene related to neuroticism individually carries very little risk of developing neurotic personality, Chen says. As with most human traits, "there may be hundreds or thousands of genes related to neuroticism," she says. "If someone carries a few of these genes, it doesn't mean this person will develop neurotic personality." For someone carrying more of these genes, putting them at higher genetic risk, she says, "adverse environmental factors could trigger development of neurotic personality or mental illness."

Avoiding or reducing stress, practicing positive thinking and being in a socially supportive environment provide a buffer against negative influences, Chen says. "Through experience, education and environment – the people around you – a lot of things can be changed."

Kotov notes that there's no overlap between personality traits and cognitive disorders such as Alzheimer's disease or dementia. And there is only modest crossover between emotional traits like neuroticism and behavioral disorders like ADHD.

Even when personality traits make people more prone to developing mental disorders, many other factors determine whether that escalation occurs. Hormonal changes, accidents and stressful events play a role. Age does, too. For instance, Kotov says, a teen with high levels of introversion would be at higher risk than a similar middle-aged adult who has found ways to cope and succeed.

Traits like neuroticism can present a survival advantage, Kotov says. People with too-low neuroticism may take too many risks, he says, such as suffering accidents when carelessly crossing the street or jumping into iffy financial ventures.

Wary neurotic people may be more attuned to possible threats, for instance in their job environments. "Do you work with reliable, friendly colleagues or in a culture where backstabbing is the norm?" Kotov says. If it's the latter, some neuroticism might be appropriate. But at extreme points, neuroticism becomes maladaptive, he says, when fears, discouragement, jealousy and simmering anger become a burden, affecting what people do and limiting their lives.

You can temper personality traits like anger, Kotov says. Talk therapy, medications like Prozac and coping strategies can help keep continual annoyance and irritation from progressing to outright explosiveness. People with high hostility levels "aren't necessarily getting into major problems like bar fights or getting fired," he says. "But they can get provoked and lose control."

With counseling, Kotov says, someone struggling with a short fuse could gain a new perspective on other people's actions. He or she could learn to see gray areas and be less likely to lash out. Basically, he says, it's about dealing with emotions in ways that aren't counterproductive. While it's not ironclad, he says, it's thought that managing unhelpful personality traits now promotes better mental health later.

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