If a woman you know has an overactive thyroid, you might want to keep a beady eye on her.
Psychologists have discovered a surprising link between hyperthyroidism and dark personality traits – including psychopathy.
Hyperthyroidism – which is about 10 times more common in women than men – occurs when the thyroid gland in the neck produces too many hormones.
It can trigger a range of symptoms including mood swings, difficulty sleeping, palpitations and nervousness.
Now, a study has revealed that people with the condition have higher levels of psychopathy, Machiavellianism and sadism compared to those with normal thyroid function.
‘These preliminary findings suggest that elevated thyroid hormone levels may be associated with a personality profile marked by greater antagonism and reduced empathic functioning,’ the researchers said.
The findings could help with the ‘early identification’ of risk factors for antisocial behaviour such as psychopathy – and even lead to an easy treatment, according to the experts.
‘Effective treatment approaches may benefit from addressing both hormonal regulation and psychological well–being,’ they concluded.
If a woman you know has an overactive thyroid, you might want to keep a beady eye on her. Psychologists have discovered a surprising link between hyperthyroidism and dark personality traits – including psychopathy. Pictured: Jodie Comer as the psychopath Villanelle in Killing Eve
An overactive thyroid, known as hyperthyroidism, occurs when the thyroid gland in the neck produces too many hormones (file image)
For their study, the team, from Ashkelon Academic College in Israel, recruited 154 adults to complete online surveys.
Based on their medical history, 49 were categorised as having an overactive thyroid, while 52 had an underactive thyroid and 53 did not have any thyroid disorder.
They were also given questionnaires to determine personality traits.
This included asking them how much they agreed with statements such as ‘I have a unique talent for persuading people’, ‘Some people deserve to suffer’ and ‘I really enjoy violent films and video games’.
Compared to the healthy control group, the hyperthyroidism group showed elevated scores of psychopathy –scoring higher on questions linked to impulsivity and callousness.
They also scored higher for sadism – the enjoyment of hurting or dominating others – and Machiavellianism, measured by answers linked to manipulation and cynicism.
The findings, published in the journal Current Psychology, suggest that imbalances in the hormonal system may influence aversive personality traits.
‘Our findings are consistent with prior research associating elevated thyroid hormone levels with increased aggression, hostility and impulsivity, behavioural patterns that substantially overlap with characteristics of the dark personality spectrum,’ the team wrote.
Researchers found that psychopathic traits, like those of fictional psychopath Patrick Bateman in American Psycho (pictured), are more likely in people with an overactive thyroid
They explained that hyperthyroidism is characterised by elevated levels of the hormones T3 and T4, which increase metabolic rate and heighten central nervous system activity.
‘This hyper–aroused state has been linked to emotional instability, impulsive behaviour and heightened aggression,’ they wrote.
‘Psychologically, individuals with hyperthyroidism frequently experience chronic anxiety, irritability, and affective instability which may exacerbate interpersonal antagonism, emotional detachment, and manipulative behaviours.’
Hyperthyroidism can affect anyone, but is 10 times more common in women than men and typically occurs between the ages of 20 and 40.
Figures suggest that 2.7 per cent of women and 0.23 per cent of men in the UK suffer from the condition.
Treatment can include medicine to prevent the thyroid producing excess hormones, radioactive iodine treatment to destroy cells, or even surgery to remove part of the thyroid.
‘Recognizing the emotional and personality profiles associated with thyroid hormonal imbalances may enhance therapeutic outcomes by enabling earlier identification of individuals who may benefit from psychological support,’ the researchers added.
‘Integrating psychological insights into the clinical management of thyroid dysfunctions extends the scope of care beyond physiological regulation alone.’
Psychologists have previously unearthed a strong connection between ‘quiet quitting’ and dark personality traits.
Quiet quitting is a trend where workers don’t leave their jobs outright, but simply fade into the background by doing only what is absolutely required of them.
Researchers found that high levels of psychopathic and narcissistic traits make someone significantly more likely to quiet quit.
The scientists say that people with these traits have a greater sense of entitlement and feel less guilt about holding back when their expectations aren’t met.



