A study published in January's American Journal of Psychiatry found a strong correlation between people with lower childhood IQ scores and an adult diagnosis of mental illness.
The study was performed on the "Dunedin Cohort," a thousand-strong group of New Zealanders who have been tracked since their births in 1972-73. It was from this population that we got the first strong evidence involving the link between genetic vulnerability to stress and depression, which has led to a lot of re-thinking into cause and effect across the whole panoply of mental illness.
The current study involved a lot of the same researchers as the stress-depression study. The cohort was administered IQ tests at ages 7,9, and 11. Psychiatric evaluations were made at ages 18, 21, 26, and 32. The researchers found that "lower childhood IQ was associated with increased risk of developing schizophrenia spectrum disorder, adult depression, and adult anxiety."
Intriguingly, "higher childhood IQ predicted increased risk of adult mania." The authors of the study do caution, however, that this particular finding may represent a statistical anomaly.
Back in the 70's, Nancy Andreasen MD, PhD of the University of Iowa spotted a measurable bipolar-creativity link, and Kay Jamison's "Touched with Fire" of 1996 put the issue out in front of the public. But she also noted that:
"Thinking can range from florid psychosis, or madness, to patterns of unusually clear, fast, and creative associations, to retardation so profound that no meaningful activity can occur."
Indeed, the psychiatric literature is full of studies pointing to serious cognitive flaws in bipolar patients. In a study published in 2004, for instance, Deborah Yurgelun-Todd PhD of Harvard and her colleagues scanned the brains of 11 stable bipolar patients while performing a mental processing task, and found significant delays in their ability to respond with correct answers compared to 10 healthy controls.
The study also found decreased activation of the brain region responsible for processing the task compared to the controls.
That same year, at the APA annual meeting, I heard Dr Yurgelun-Todd propose that cognitive deficits should be regarded as a core feature of bipolar disorder.
In the current study, the authors point out that "lower childhood IQ may be a marker of neuroanatomical deficits that increase vulnerability to certain mental disorders." They also note the debilitating effects of stress and trauma.
What to make of all this? Some days our brains are running on rocket fuel; other days, molasses. Neither state is solely good or bad. Our best work often occurs at either pole. So do our worst moments.
Technically speaking, if our brains were manufactured goods, there would have been a product recall ages ago. But, here's the rub: Knowing that's the case, are you ready to turn yours in?
Further reading from mcmanweb: The Thought Spectrum
These days, my internal operating system is far and away the worst aspect of my illness I have to contend with. Moods, shmoods – I actually follow some of the advice in my book, "Living Well with Depression and Bipolar Disorder." But when my brain unexpectedly cuts out on me, what am I to do? These are no mere senior moments. The software simply isn’t loading right. When it happens, I know it and the people around me know it. This has been going on for as long as I can remember.
If you don’t think this is any big deal, then ask yourself: Knowing what you now know about me, how safe would you feel with me as an air traffic controller?