Are intelligence And Depression Directly (Or Indirectly) Related?

Updated September 24, 2018

If you are intelligent, are you more likely to be depressed? Not depressed? Less depressed? Do intelligence and depression have any relation?

Are the stereotypes true about geniuses who are melancholy, dark individuals susceptible to mood swings and bouts with true depression? The research in this area shows some conflicting things.

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Lower IQ - More Likely To Be Depressed

One study from the Adult Psychiatric Morbidity Survey in England concluded that people with a lower intelligence quotient (IQ) are less happy than their more intelligent peers.

Test subjects with an IQ in the 70-79 range, which is considered in the lower spectrum, defined themselves as being less happy than peers with IQs in the upper end of the spectrum (around 120) who were considered "gifted" or above average intelligence. The survey asked respondents questions about whether they were usually in a good mood, how satisfied with the life they felt, and other questions meant to determine their overall happiness and contentment.

The thought pattern here is that people with lower IQs, due to less ability and therefore limited life choices (less education, lower earning potential, jobs without insurance, sick days, or vacation, etc.) end up with an overall lower socioeconomic status, which brings about a lower quality of life. Data suggests it is lack of opportunity that leads to unhappiness compared to those with a higher IQ.

Another long-term study focused on the relationship between low childhood IQs and mental disorders later in life. Researchers at Harvard School of Public Health (HSPH) discovered that children with lower IQs illustrated an increased risk of developing psychiatric disorders as adults. According to Karestan Koenen, assistant professor of society, human development, and health at HSPH, "Lower childhood IQ predicted an increased risk of schizophrenia, depression, and generalized anxiety disorder. Individuals with lower childhood IQs also had more persistent depression and anxiety and were more likely to be diagnosed with two or more disorders in adulthood."

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The participants were part of the Dunedin Multidisciplinary Health and Development Study. The group was comprised of 1,037 children born in Dunedin, New Zealand from 1972-73. They were initially assessed at age 3 and evaluated every two years until age 15, then at 18, 21, 26, and 32. Their IQs were tested at ages 7, 9 and 11. Mental disorders were then assessed from ages 18 until 32 by clinicians with no prior knowledge of the participants' history.

Koenen says that these findings might be helpful when treating individuals with mental health disorders. "Lower childhood IQ was associated with greater severity of mental disorders including persistence over time and having two or more diagnoses at age 32," said Koenen. "Since individuals with persistent and multiple mental disorders are more likely to seek services, cognitive ability may be an important factor for clinicians to consider in treatment planning. For example, individuals with lower cognitive ability may find it harder to follow instructions and comply with treatment regimens. By taking clients' cognitive ability into account, clinicians may improve treatment outcome," she said.

These findings may also help in prevention planning. "Educators and pediatricians should be aware that children with lower cognitive ability may be at greater risk of developing psychiatric disorders. Early detection and intervention aimed at ameliorating mental health problems in these children may prevent these problems from carrying over into adulthood," said Koenen.

The reason lower childhood IQs might lead to increased risk for mental disorders is not yet explained, but there are a few possible theories. One theory suggests that a lower childhood IQ might show a difference in brain health, therefore making an individual more susceptible to certain mental disorders. Another theory is that stress is a culprit. The theory suggests that children with lower IQs are less equipped to deal with stress in daily life. This lesser ability makes them more vulnerable to later developing one or more mental disorders.

Depression - More Likely To Perform Poorly On IQ Test

Another school of thought is that depression and intelligence are related, but depression causes a low IQ "to show up" so to speak. In other words, depression lowers a person's ability to perform.

An experiment was conducted on two groups of people; those with varying degrees of depression, and those who were of a healthy mental state. The group classified with depression performed significantly poorer on given IQ tests than the group classified as mentally healthy.

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Some researchers explained this finding as depression lowering the brain's ability to function properly in the area of the frontal cortex (also referred to as the frontal lobe). The frontal cortex is our main control center, responsible for cognitive functions such as reasoning and problem solving, and it controls judgment, language, memory, and other important processes. It is the part of the brain that makes us feeling, thinking, acting individuals.

So, if depression is present, any individual, regardless of his or her IQ, cannot make the most of ability when performing certain activities. It is possible in this way to see how depression could affect performance on an IQ test. Most people have an IQ in the average range. It is possible to see what might happen when testing an average group of people who have depression - they may score lower on average.

Higher IQ - Might Mean Depression…And More

So, does this mean that people with a higher IQ do not become depressed? Not quite.

Other researchers believe that people with above-average IQs may still develop depression and are even more likely to develop other mental disorders, such as clinical depression and bipolar disorder.

In one study published in the British Journal of Psychiatry, strong school performance was linked to nearly four times the average risk of developing bipolar disorder. Research indicated that bipolar disorder might be up to four times more common in straight-A students.

Dr. James MacCabe, the lead researcher at the Institute of Psychiatry, King's College London, says, "We found that achieving an "A" grade is associated with increased risk for bipolar disorder, particularly in humanities and to a lesser extent in science subjects. These findings provide support for the hypothesis that exceptional intellectual ability is associated with bipolar disorder."

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Another study published in the journal Intelligence shows more evidence relating higher intelligence to mental conditions such as depression. Ruth Karpinski and her colleagues of Pitzer College surveyed with members of Mensa, an organization for people with IQs in the top 2% of the U.S., usually over 130. At the conclusion of the study, answers provided by Mensa members found that they suffered from more mental disorders than people with average intelligence.

Disorders including depression and bipolar (mood disorders), anxiety disorders, attention-deficit hyperactivity disorder, and autism were assessed. Members were asked whether they had ever been formally diagnosed with any of the disorders, or whether they thought they might suffer from it.

Over 26% of members had been formally diagnosed with a mood disorder, and 20% an anxiety disorder. These percentages were significantly higher than the national averages, which are around 10%.

Karpinski and colleagues theorize this as what is called the hyper brain/hyper body theory. This theory suggests that high intelligence is thought to be associated with psychological and physiological "overexcitabilities," or OEs. An OE is an unusually intense reaction to environmental stimuli.

This can present as a heightened potential to worry and overthink about what they say or what might occur around them or to them. These tendencies may trigger depression, anxiety, or other responses. Karpinski is careful to point out that while this shows a relation, it does not prove that a higher IQ is the cause of having a disorder.

When considering children with higher IQs, depression seems to become more of a possibility the higher the IQ reaches. In "Watching Prodigies for the Darkside," published in Scientific American, psychiatrist Marie-Noëlle Ganry-Tardy says that around 3% of children are highly gifted (having IQ scores of at least 130), which usually gives them an advantage in school.

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However, for the most exceptionally gifted (having IQ scores above 140), the advantages begin to dwindle. Ganry-Tardy explains that these unusually bright children become very insightful at a young age. This insightfulness brings about adult problems, such as being aware of the potential risk of failure or fear of not being accepted by other children. This emotional awareness can immobilize children "to the point of emotional paralysis" says Ganry-Tardy. It is easy to see how these situations could lead to depression, anxiety, and other issues for a child.

It may seem confusing as to which theory, if any, seems the most plausible. Does a person who is… 1) not very intelligent have problems leading to depression? 2) depressed have a problem performing intelligently? 3) highly intelligent have tendencies to be depressed? Each theory seems to have support based on the evidence presented in this article.

However, one thing is for certain, regardless of the root causes of depression, it can be a debilitating condition for anyone to experience, no matter what their intelligence level. If you or someone you love is experiencing symptoms of depression, please seek help from a mental health professional like the ones at Betterhelp.com.

References

Ali, A., Ambler, G., Strydom, A., Rai, D., Cooper, C., McManus, S., Weich, S., Meltzer, H., Dein, S., & Hassiotis, A. (2012). The relationship between happiness and intelligent quotient: the contribution of socio-economic and clinical factors Psychological Medicine, 43 (06), 1303-1312 DOI: 10.1017/S0033291712002139

Braw, Y., Aviram, S., Bloch, Y., & Levkovitz, Y. (2011). The effect of age on frontal lobe-related cognitive functions of unmedicated depressed patients Journal of Affective Disorders, 129 (1-3), 342-347 DOI: 10.1016/j.jad.2010.07.032

Gorlyn, M., Keilp, J., Oquendo, M., Burke, A., Sackeim, H., & John Mann, J. (2006). The WAIS-III and Major Depression: Absence of VIQ/PIQ Differences Journal of Clinical and Experimental Neuropsychology, 28 (7), 1145-1157 DOI: 10.1080/13803390500246944

Koenen, K. C., Moffitt, T. E., Roberts, A. L., Martin, L. T., Kubzansky, L., Harrington, H., . . . Caspi, A. (2009). Childhood IQ and Adult Mental Disorders: A Test of the Cognitive Reserve Hypothesis. American Journal of Psychiatry, 166(1), 50-57. doi:10.1176/appi.ajp.2008.08030343

Kyaga, S., Lichtenstein, P., Boman, M., Hultman, C., Langstrom, N., & Landen, M. (2011). Creativity and mental disorder: family study of 300 000 people with severe mental disorder The British Journal of Psychiatry, 199 (5), 373-379 DOI: 10.1192/bjp.bp.110.085316

MacCabe, J., Lambe, M., Cnattingius, S., Sham, P., David, A., Reichenberg, A., Murray, R., & Hultman, C. (2010). Excellent school performance at age 16 and risk of adult bipolar disorder: national cohort study The British Journal of Psychiatry, 196 (2), 109-115 DOI: 10.1192/bjp.bp.108.060368

Weismann-Arcache, C., & Tordjman, S. (2012). Relationships between Depression and High Intellectual Potential Depression Research and Treatment, 2012, 1-8 DOI: 10.1155/2012/567376


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