An underactive thyroid and personality

What we call personality is the relatively permanent pattern of feelings, thoughts and behaviours that make people respond in certain ways under given circumstances (1).

Research has shown that there is a mix of genetic and environmental impact on the personality (2). Thyroid hormones are known as modulators of people’s abilities to learn, understand and react, in addition, research has shown that the change, the lack or the abundance of thyroid hormones can impact behavioural patterns in people (3).

How can thyroid hormones impact behavioural patterns (3–9):

• TSH levels on the higher end of the normal range are associated with higher persistence, self-directedness (the ability to regulate and adapt behavior to the demands of a given situation), being more optimistic, less shy, and less concerned or worried about different issues.
• TSH levels on the lower end of the normal range are associated with the increased risk of developing depression.
• fT4 levels on the higher end of the normal range are associated with a lower dependence on signals of social approval, and social support.
• tT4 levels on the higher end of the normal range are associated with reduced social attachment.
• T3 levels on the higher end of the normal range are associated with antisocial and in rare cases aggressive behavior

Even if your lab tests values are located towards the upper part of the normal range, it does not mean you will have any of the behavioural patterns listed, each individual may react differently. If you feel your personality has altered during the course of your condition, it is good to talk to your doctor about any further treatment options.

How we write: our information is based on the results of peer reviewed studies using the National Library of Medicine platform. It is written by scientists and reviewed by external experts. If you believe we might have overseen crucial scientific information, please contact us at hello@boostthyroid.com

Disclaimer: This information is not intended to mitigate, prevent, treat, cure or diagnose any disease or condition. If you want to change your treatment, lifestyle, your diet, include supplements in your diet or have concerns about your health, please consult your doctor before trying new approaches.

References:

1. Roberts BW. Back to the Future: Personality and Assessment and Personality Development, 2009
2. Sanchez-Roige S, et al. The genetics of human personality, 2018
3. Piskunov A, et al. The hypothalamic-pituitary-thyroid axis and personality in a sample of healthy subjects, 2018
4. Arque JM, et al. Correlation of thyroxine and thyroid-stimulating hormone with personality measurements: a study in psychosomatic patients and healthy subjects, 1987
5. Frey A, et al. Thyrotropin serum concentrations in healthy volunteers are associated with depression-related personality traits, 2007
6. Sinai C, et al. Thyroid hormones and adult interpersonal violence among women with borderline personality disorder, 2015
7. Uter JC, et al. Single Nucleotide Polymorphisms in Thyroid Hormone Transporter Genes MCT8, MCT10 and Deiodinase DIO2 Contribute to Inter-Individual Variance of Executive Functions and Personality Traits, 2020
8. Brandt F, et al. Hyperthyroidism and psychiatric morbidity: evidence from a Danish nationwide register study, 2014
9. Stalenheim EG, et al. Serum levels of thyroid hormones as biological markers in a Swedish forensic psychiatric population, 1998

Photo: Marianne Bos, Unsplash; Design: VLM Health