Depression And Intelligence: Exploring The Relationship Between Them

You may wonder whether depression and intelligence are connected. With media showcasing people with higher intelligence as isolated, lonely, and melancholy individuals, it can seem that those who have high levels of intelligence are more likely to be diagnosed with depression or other mental health problems than the general population. Understanding the relationship between your cognitive ability and depression can help you further understand your symptoms and how to receive mental health support. However, note that the research in this study area is slightly conflicting.

Intelligence appears in different ways for different people and there are significant differences in what is considered intelligent across cultures. There are many factors that may impact intelligence including genetic factors, environmental factors, and mental and physical health factors. In terms of general intelligence, many modern-day psychologists still rely on the IQ test. In the United States the national average IQ is 98 while a score of 140 is considered genius level.

Looking at the research: are depression & intelligence linked? 

In the field of psychology, cognitive epidemiology and cognitive aging experts study the link between intelligence and other disorders. While research suggests that the correlation between IQ and depression is complicated to explain, below are a few examples of previous research on adult IQ, childhood IQ, and depression and the correlations discovered between them. 

Adult psychiatric morbidity survey 

One 2013 study from the Adult Psychiatric Morbidity Survey in England looking at depression and general intelligence concluded that people with a lower intelligence quotient (IQ) are less happy and more likely to develop depression or depressive symptoms than those with a higher IQ. 

Test subjects with lower intelligence (an IQ in the 70-79 range) defined themselves as less happy than peers with high IQs in the upper end of the spectrum (around 120) who were considered "gifted" and above average in intelligence. The survey gathered information from respondents such as whether they were usually in a positive mood, how satisfied they felt with life, and other questions, to study their overall happiness and contentment.

One possibility with these results could be that people with lower IQs, due to less ability and potentially limited life choices, may have a lower overall socioeconomic status, which may bring about a lower quality of life and well-being. On the opposite end of the spectrum, people with higher intelligence may be able to pursue more opportunities that improve their quality of life, and ultimately lower their risk factors for developing major depression.

Another long-term study focused on childhood intelligence and the relationship between low childhood IQs and mental disorders later in life. In 2008, researchers at Harvard School of Public Health (HSPH) discovered that children with lower IQs illustrated an increased risk of developing psychiatric disorders (such as mood disorders and anxiety disorders) and worse mental health outcomes as adults when compared with higher scores. 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."

The participants were part of the Dunedin Multidisciplinary Health and Development Study. The group comprised 1,037 children born in Dunedin, New Zealand, from 1972 to 1973. 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 illnesses were then assessed from ages 18 until 32 by clinicians with no prior knowledge of the participants' history of health conditions.

Koenen says that these findings and complete data might be helpful when treating adults in middle-age with mental illness. For example, some clients may have more difficulty than others when it comes to following treatment plans and remaining consistent with instructions, as their cognitive ability makes it challenging to do so. Clinicians can consider these areas when considering techniques to teach clients. These findings may also help in prevention planning. For example, IQ testing may help with early prevention and diagnosis when it comes to major depression and other conditions.

Low childhood IQ & mental disorders

The reason lower childhood IQs might lead to increased risk for mental disorders, such as major depression, is not yet explained, but there are a few possible theories and factors. One theory suggests that a lower childhood IQ might show a difference in brain health and executive function, making an individual more susceptible to certain mental disorders than someone with higher intelligence. In one study researchers used an odds ratio measure to determine if there was a correlation between IQ and depression. The odds ratios showed, with high reliability, that there are strong associations between childhood IQs and depression severity. 

Another theory is that stress is a culprit. In addition, researchers consider whether children with lower IQs are less equipped to deal with stressful life events or more likely to find themselves in stressful situations. Less cognitive ability might make them more at risk of developing one or more mental disorders or depression symptoms.

Another school of thought is that depression and intelligence are related, but depression negatively impacts cognitive function and causes a low IQ score on the test. Researchers hypothesize that depression can cause performance challenges, lack of focus, distress, or other possible mediators during IQ testing. 

An experiment was conducted on two groups to test this theory. One group had varying degrees of self-reported depression, and one had a healthy mental state. The group with a clinical diagnosis of depression performed significantly more poorly on given IQ tests than the group classified as mentally healthy.

Some researchers explained this finding as depression lowering the brain's ability to function appropriately in the frontal cortex (also referred to as the frontal lobe). The frontal cortex is the brain's main control center, responsible for cognitive functions like reasoning and problem-solving. It also controls judgment, language, memory, and other essential processes.

Higher IQ & mental disorders

Anyone, including highly intelligent people, can be diagnosed with depression, regardless of previous mental health and well-being. Some researchers believe that people with higher IQs may be more likely to develop mental health conditions like clinical depression, bipolar disorder, or anxiety disorders.

In one longitudinal study published in the British Journal of Psychiatry, strong school performance was linked to nearly four times the average risk of developing bipolar disorder. In addition, research indicated that bipolar disorder might be up to four times more common in straight-A students with grades well above the standard deviation of the mean.

Dr. James MacCabe, the lead researcher at the Institute of Psychiatry at King's College, London, stated, "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."

In another study, mental illnesses, including depression, bipolar disorder, and anxiety disorders, and neurodivergent identities like attention-deficit hyperactivity disorder (ADHD) and autism were assessed. Their results suggest that a highly intelligent person with a high IQ has a higher risk of developing psychological disorders. Karpinski and colleagues call this positive association the hyperbrain and hyperbody theory. This theory suggests that high intelligence is associated with psychological and physiological "overexcitabilities," or OEs. An OE is an unusually intense reaction to environmental stimuli.

Physiological overexcitability can present a high potential to worry and overthink about what an individual says or what might occur to and around them. These tendencies may cause depression, anxiety, and other responses. However, Karpinski is careful to point out that while this shows a relation, it does not prove that a higher IQ is the cause of a mental condition. Having a higher IQ also does not counteract disorders like attention-deficit/hyperactivity disorder. 

When considering children with higher IQs, depression was also found to be more likely on the higher end. In "Watching Prodigies for the Dark Side," published in Scientific American in 2005, psychiatrist Marie-Noëlle Ganry-Tardy says that around 3% of children are highly gifted (i.e., having IQ scores of at least 130), which often gives them an advantage in school. 

However, the advantages in the study dwindled for the most exceptionally gifted (i.e., having IQ scores above 140). Ganry-Tardy explains that children with an IQ over 140 become insightful at a young age and their processing speed is faster than their peers and many adults. This high intelligence and insightfulness can bring about adult problems, such as being aware of the potential risk of failure or fear of not being accepted by other children, and being more aware of bad news in the world. This emotional awareness can immobilize children "to the point of emotional paralysis," says Ganry-Tardy. These situations may lead to depression for a child, teen, or adult.

Counseling options for depression

It may seem confusing as to which theory is most plausible, and it is challenging to give a detailed description of how IQ impacts mental health as there are differing opinions on the topic. It is important to remember that even if there is a link between depression and intelligence, there is still only one risk factor and simply having a low or high IQ doesn’t mean that a person will experience a mental health condition like depression. 

Regardless of the root causes of depression, it can be a debilitating health condition for anyone to experience, no matter their IQ. In addition, there are multiple types of intelligence, and someone with a low IQ may be intelligent in another area, such as emotions, art, or music. Regardless of your IQ, if you're experiencing depression, consider reaching out for support. 

Many people who are seeking to improve their adult mental health face barriers to treatment with an in-person therapist, so if you struggle to afford therapy, you might benefit from trying online counseling. Through platforms like BetterHelp, you can connect with a licensed professional from home and choose between phone, video, or live chat sessions. If you're struggling to get out of bed or care for yourself due to a depressive episode, depression symptoms, or a mood disorder, you can attend online therapy from home with a stable internet connection. 

In addition, various clinical studies have demonstrated that online therapy effectively treats depression. Many people who engage in online therapy see a significant reduction in their depression symptoms. Online therapy is also often more cost-effective than traditional in-person therapy models.