Shaped like a butterfly, the thyroid sits at the bottom of your neck, just in front of your windpipe. It may be small, but the hormones it produces influence important bodily functions such as heart rate, digestion, energy levels, body temperature and mood.
Around 1 in 20 of us lives with a thyroid problem.
When the thyroid gland doesn’t produce enough thyroid hormone, this is known as hypothyroidism, or an underactive thyroid.
The thyroid can also produce too much hormone, which is known as hyperthyroidism, or an overactive thyroid.
A large international research study showed that more than half (54.2 per cent) of people with underactive thyroids reported higher levels of Type D personality traits, which included pessimism, stress and social inhibition.
The study authors suggest that there may be a link between thyroid hormone levels and negative personality traits.
But what about the relationship between thyroid problems and ‘darker’ personality traits, like narcissism and psychopathy?
Although very little research has explored this, one recent smaller study of 154 adults compared people with hypothyroidism, hyperthyroidism and no thyroid disorder.
The researchers found that people with hyperthyroidism showed higher levels of psychopathy, sadism and, to a lesser extent, narcissism.
In contrast, people with hypothyroidism appeared mostly similar to those who didn’t have any thyroid conditions at all (the control group).
This suggests that increases in ‘darker traits’ may be specific to having an overactive thyroid, rather than thyroid problems in general.
So how might the relationship between an overactive thyroid and ‘darker traits’ work?
The study authors suggested that when thyroid hormone levels are high, the body goes into overdrive, speeding up metabolism and increasing brain activity. This heightened arousal can make it harder for people to regulate their emotions and impulses.
The findings of both studies are interesting, but it’s important to remember that they show associations between factors, not causation.
For example, we know that when ice cream sales increase, so do shark attacks. But eating ice cream doesn’t cause shark attacks. The real factor is heat. Hot weather is responsible for more people visiting the beach and more ice cream sales.
So, although the two things look linked, one doesn’t cause the other. We need to apply the same caution when thinking about thyroid research. We cannot assume that having a thyroid condition causes the development of dark personality traits.
While research demonstrates that the mind and body are interlinked, having especially low or abnormally elevated levels of thyroid hormones cannot, on their own, cause someone to become a narcissist or psychopath, as far as we know.
This article is an answer to the question (asked by Sienna Thompson, via email) 'Can your thyroid make you a narcissist?'
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