IQ, Intelligence, and Mental Illness

There’s been some hypothesizing about the link between bipolar disorder and creativity, but how does IQ and intelligence correlate with mental disorders such as Schizophrenia and Bipolar disorder? The results are mixed, but interesting. Specifically, there is some disagreement between the IQ of an individual and the risk of developing bipolar disorder. However, the level of academic achievement, which might be a measure of creativity as well as intelligence, reveals a contrary position, supporting a possible premorbid link between bipolar disorder and general intelligence.

First, the bare facts. It’s been long thought that creativity is associated with bipolar disorder. The evidence is often anecdotal, but convincing to some degree. Great artists and mathematicians have long been thought to have the disorder, van Gogh, Pollock, Kurt Cobain, DMX, Graham Greene, Edgar Allen Poe, Virginia Woolf, and ground breaking mathematicians Georg Cantor and Emil Post. These artists are along with numerous actors and comedians and politicians (like Lincoln and Churchill). It seems that intelligence and creativity runs along side bipolar disorder.

But what about IQ, a very analytical test of intelligence. First, there must be some distinction between IQ tests. There are several methods of testing, but here I will focus on two: Raven’s Progressive Matrices (RPM) and National Adult Reading Test (NART). RPM is the test where they have the patterns of tic-tac-toe type images and then ask you which shape should complete the pattern. It is not an IQ test in the normal sense, it is a test of fluid intelligence. Fluid intelligence is the type of intelligence that determines how well one responds to new information without any background knowledge. This is opposed to the NART method, which allows for one’s previous knowledge to influence the results, that is, it allows crystalized intelligence to influence the results. Additionally, NART is not a full blown IQ test, rather it is a solid predictor of IQ. I wish I could have found a solid longitudinal test using something along the lines of the Stanford Binet test, but all the evidence that I could find used NART.

So the results of the NART testing found no correlation between premorbid IQ and developing bipolar disorder within 27 years of the test. However, they did find that lower IQs were associated with non-affective disorders like schizophrenia and psychosis.

However, it does not mean that IQ holds steady after the onset of bipolar disorder. In a PsychoMed article it’s found that there is even a discrepancy between bipolar I and II. In terms of IQ decline, it’s found that persistent depression leads to a higher risk of cognitive abnormalities. So perhaps mania is an offset to this decline.

Finally, there does seem to be a risk factor between general intelligence and the risk of bipolar disorder. In a study on Swedish students aged 16 who were A students, the study found that there was an increase in the likelihood of developing bipolar disorder. And the results were profound. There was a four fold increase in risk of developing bipolar disorder associated with achievement in school. Indicating that general intelligence, including both fluid intelligence and crystalized intelligence does have some correlation with developing bipolar disorder. Specifically, higher scores associated with music and language experienced higher risks. In addition to this, there was a 12 fold increase in the risk of developing bipolar disorder associated with high scores in arithmetic. Specifically, it is found that the risk of developing psychosis is associated with lower IQs as compared to higher IQs. This is a finding in keeping with the NART scores previously mentioned. The final finding of the meta analysis that psych central provided was that this indicates a different causal pathway between schizophrenia, bipolar disorder, and depression.


Posted on October 20, 2011, in Bipolar, Mental Health and tagged , , , , , , , , . Bookmark the permalink. 6 Comments.

  1. THANK U SO MUCH! I have lots of problems “in my brain” i think… this was great to read!

  2. The 12 fold increase is interesting. Those are two domains that I have always excelled in.

    Pick up the book, “Touched with Fire”. I have hardly started it, but it explores the correlation between BP and creativity.

    Now, I have some thoughts on the IQ. Depression is literally that. We know that people in a depressive state, BP or MDD, literally have a depressed brain. In a way, it’s kind of how we could expect unaffected folks to perform if they were drunk. Depression slows brain functions, therefore it would slow cognition and memory. Mania is the opposite. Therefore, it would largely depend on when a person with BP took the test – depressive or manic? And if you account for all of the people with MDD who were in the midst of an episode at the time, then you would have some really skewed results.

    Also, take into consideration that medications play their part too. Some mood stabilizers, (notably Lamictal and Topamax), are known for their effects on cognition and memory. This varies greatly between people. Personally, I monitor my IQ by taking a test every so often. I can honestly tell you that I’ve seen a gain in some areas (visual, logical, math) and a loss in others (memory). But, it has really been an overall gain – 5 points. Yeah, it’s negligible, I suppose.

    And the data might be a little tainted because my treatment was within the first year of having my first child. Some evidence suggests womens’ IQ’s increases upon having children because their spacial reasoning changes. The gain is related to some kind of inborn mechanism that goes off that allows women to monitor their young by visually multitasking. It’s primal women were able to gather, tend young, and watch for predators.

    So, is it the high stress environment that sets the mental íllness, or is it the mental illness that makes for the high achievement? The research raises some interesting questions. Can an abundance of creativity lend intelligence?

  3. This is an amazingly interesting piece. I haven’t time to read the articles now so will have to get back to you after I have BUT as a clinician who routinely assesses how cognition in function is affected by a person’s illness I can tell you this.
    Anecdotally – people with straight up and down Bipolar disorder retain cognitive function much better than most other disorders UNLESS there is substance use involved
    someone with Schizoaffective disorder doesn’t retain as much function as Bipolar – but a certainly tends to retain more than someone with Schizophrenia
    People with Paranoid type schizophrenia seem to retain more than other types of schizophrenia (consistent with literature also)
    People who have longer periods of untreated depression don’t seem to retain as much as people who have had well managed depression
    Depression does seem to slow down cognitive processing to some extent although this varies to some extent depending on how well the person is on the time.
    Again …. the above are all anecdotal observations and I work predominantly with people with serious and persistent mental illness. They are observations about how much of what people have makes it to the table for use rather than IQ. But yes, people with Bipolar usually tend to do better here too. The people who assess this stuff just tend to belong to a profession that don’t formalist their research and write it up very often. It would be interesting to put the IQ data and the functional data together sometimes. Most of the time they match – but in disorders like Anxiety disorders eg OCD, agoraphobia etc it’s often not even close.
    I will be keen to read your articles once my visitors go home.

  4. I just finished reading My Stroke of Insight by Jill Bolte Taylor. In it, she describes the differences between the left brain and the right brain. The left brain is the dominate hemisphere in most individuals and it controls all the details in life like language, mathematics, etc. The right brain controls the fluid input to the brain – your “in the moment” hemisphere which can make you feel part of the universe as a whole. Your description of the two tests suggests to me that the RPM test involves the right brain more than the left, and the NART test involves the left brain more than the right. It could be that one or both tests actually involve both hemispheres and the communication sections of the brain, but upon first glance it seems like they test different hemispheres. I am curious to know if this is the case. Did you come across any information regarding the tests and hemisphere dominance?

    • Unfortunately no. There’s actually limited studies linking intelligence to bipolar/mental illness in general. I’m sure that more pubmed searching will reveal more, but in general there are few studies to begin with and probably even fewer testing hemispherical discrepancies.

  5. I am new to your blog and I read a couple of articles. I was just blown away. How can a manic depressive guy write such intriguing articles. I have bookmarked your blog and will be coming back soon. Keep posting frequently. Thanks.

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