If you know a woman who has an overactive thyroid, it might be wise to observe her closely.

Recent studies by psychologists have uncovered an unexpected correlation between hyperthyroidism and certain dark personality traits, such as psychopathy.

Hyperthyroidism, which is approximately ten times more prevalent in women than in men, occurs when the thyroid gland located in the neck produces an excessive amount of hormones.

This condition can lead to a variety of symptoms, including mood fluctuations, trouble sleeping, heart palpitations, and feelings of anxiety.

A recent study has found that individuals with hyperthyroidism exhibit higher tendencies towards psychopathy, Machiavellianism, and sadism when compared to those with normal thyroid function.

“These initial findings imply that increased thyroid hormone levels might be linked to a personality type characterized by heightened antagonism and diminished empathy,” the researchers noted.

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.

HOW TO SPOT A PSYCHOPATH 

Psychopaths display different traits depending on their disorder.

Common signs include superficial charm, a grandiose notion of self–worth, the need for stimulation and impulsiveness, pathological lying, the ability to manipulate others and a lack of remorse and empathy.

But despite the popular association, not all psychopaths become killers.

Experts claim people usually find psychopaths intriguing, but can’t put their finger on why. 

This is down to incongruous behaviour because psychopaths tend to do a lot of acting to deceive, or mimic normal reactions, sometimes changing their views and reactions quickly.

For example, Self–professed psychopath Jacob Wells said that upon meeting someone, he tries to become ‘the most interesting person they know’ and presumably adopts suitable interests and responses to do this.

His response also gives away another common trait – a grandiose notion of self–worth – in that he can be the most interesting person in the room.

Psychopaths occasionally tend to exhibit unconvincing emotional responses, with slip–ups including tone of voice or body language.

This may be because they are unable to understand emotions such as fear and love, but can mimic them.

Psychopaths display different traits depending on their disorder, but common signs include superficial charm and the ability to manipulate others. Despite the popular association, not all psychopaths become killers (stock image)

Generally psychopaths’ ’emotions’ are shallow and short–lived and there is a manipulative ulterior motive to showing them.

For example, Mr Wells said he offers to do favours and tells false secrets to people to gain their complete trust.

He also displays insincere charm – another trait associated with psychopaths.

He says: ‘I keep secrets, and tell them fake secrets to further gain their trust, and once they trust me enough, I ask for favours, reminding them of the favours I did them. I can get literally anything from them, which is incredibly useful.’

Psychopaths typically display an incredible ability to manipulate others and sometimes take pleasure in doing so. 

Psychopaths often have an air of superiority about them, perhaps shown by Mr Wells’ belief he can spot other psychopaths

Even expert Dr Hare, who came up with the Hare Psychopathy Checklist–Revised (PCL–R) used as a diagnostic tool to determine where someone lies on the psychopathy spectrum, warns that anyone can be duped during a short interaction with a psychopath.