Is there a link between intelligence and mental illness?

By 2012, as many as 30 scientific studies had been completed that uncovered links between creativity and mental illness, particularly disorders that affected mood [source: Hsu].

Researchers conducting one such study of Swedish teenagers discovered straight-A students were four times more likely to develop bipolar disorder, a mental illness marked by alternating moods of elation and depression, illustrating a correlation between intelligence and higher instances of mental illness. As the study subjects' emotional state transitioned from low to high, there was evidence of increased activity in the frontal lobe of the brain. This area is known for regulating creativity.

The study was expanded in 2012 to include more than 1 million participants, and researchers reported a link between artists, authors and scientists and the propensity to develop mental illness. Not only bipolar disorder, but a whole suite of mental illnesses, from drug abuse to anorexia nervosa and depression. A single gene, known as DARPP-32, is suspected to cause the link between intelligence and mental illness. A study found that people with schizophrenia were more likely to have the version of DARPP-32 that boosted performance on tasks involving thinking and filtering of information [source: National Institute of Mental Health].

Studies such as these could affect the way mental illness is understood and treated. If a scientist grapples with a bipolar disorder, but relies on the moments of brilliance that bubble up when depression transitions into mania, what is the best treatment? A medication that makes the majority of his days more bearable (and potentially keeps him from self-harm) or a behavior modification program that allows for feverish, singular obsessions? In some cases, a tandem approach is best, combining drug therapy with behavioral therapy to decrease stressful triggers or cognitive therapy to change thought patterns.

While some psychologists and researchers claim there's an "upside" to mental illness, one that produces bouts of creative and productive thinking, there is a clear downside, too. Untreated bipolar disorder, for example, can lead to substance abuse or suicide. If mental illness represents a classic case of risk versus benefits, it also is an intensely personal equation [source: Science Daily].

Of course, there's also the matter of opposing evidence. Some studies have shown no difference in IQ levels between those with bipolar disorder and those without it. Others indicate that greater acumen is a protective factor against the most psychotic illnesses and that low intellect is associated with developing, for example, severe bipolar disorder. A great deal of research is being carried out in this area, with the aim of fully understanding how this illness is linked to intelligence [source: Collingwood].

Despite its moniker, mental illness often has a biological component. Some researchers suspect it has to do with a person's inability to shut out stimuli. Selectively ignoring certain incoming sights, sounds and thoughts is a hallmark of the mentally healthy, a trait psychologists call "latent inhibition." For example, a study of nearly 200,000 20-year-old Finnish males found those with higher intelligence were more than 12 times more likely to develop bipolar disorder as they aged. The link, surmised researchers, was the capability to rapidly process information while problem-solving, a hyper-alertness thought to accompany some types of mental illnesses [source: Collingwood]. Turns out, the selective hearing your child or spouse develops when it is time to take out the trash may be a good thing.

On the other hand, biology could be behind a person's propensity for certain mental maladies. For example, researchers have discovered nerve cells in a portion of the brain called the posterior cingulate cortex become more active when monkeys explore potentially rewarding new courses of behavior instead of the normal routines. It is suspected that for people who have an obsessive-compulsive disorder compelling them to adhere to strict behavioral patterns, the flexibility to pursue new -- even potentially gratifying -- avenues is absent [source: Futurity].

And then there are those who defy their diseases. Although Tesla exhibited behaviors consistent with obsessive-compulsive disorder, his thought process was agile. Just as engineers now use computer models to construct a complicated apparatus, Tesla virtually tested and recalibrated every invention before ever building a single prototype. Only he did it entirely in his own mind!

Tesla's autobiography, in which he described his creative process, reveals that across hundreds of inventions, he never built a device that didn't work as he thought it would [source: Knapp]. The link between intelligence and mental illness -- even if we don't fully understand it -- often seems to be two sides of the same coin.