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Thyroid Dysfunction May Be Linked to Personality

Hormonal alteration influences personality.

Key points

  • Personality is affected by body systems.
  • Hormone fluctuations influence cognitive functions.
  • Hypothyroidism may affect personality.

Personality is a set of characteristics in thinking, behaviors, habits, and feelings that make one different from others. Cognitive processes, genetic factors, and environmental factors are involved in forming the personality. Although it has been suggested that the central nervous system plays a central role in personality formation, a growing body of evidence confirms the significant role of other body systems/organs in shaping personality.

Sensory perceptions allow individuals to be aware of and interact with the environment. For example, living in noisy and crowded cities is associated with anxiety and anger, and people living in hot weather areas suffer from cognitive fatigue and disturbances. Regular exercise and a healthy diet are linked to improved mental health outcomes, including reduced symptoms of depression, anxiety, and stress. Body posture can also influence personality. For instance, standing with arms raised can lead to feeling more confident and dominant than slouching with crossed arms, which results in feeling powerless and insecure. Of course, there are more examples of the role of the physique in cognition and personality, but the role of normal body-regulating systems, such as hormonal systems, is more mysterious.

Hormones are chemical compounds, such as cortisol, adrenaline, and oxytocin, which are produced by specific tissues to regulate the functions of other tissues. The hormonal systems play unique roles in maintaining the body's homeostasis. Fluctuations in hormone levels can influence mood and behavior, contributing to individual differences in personality traits such as aggression, sociability, and emotional stability. For example, hormonal changes during puberty can lead to shifts in mood, identity formation, and interpersonal relationships, impacting personality development during adolescence [1].

The thyroid gland, situated in front of the throat, produces hormones that control body metabolism and affect growth and energy expenditure, among others. Hypothyroidism is an endocrine disorder characterized by the inadequate production of thyroid hormones by the thyroid gland. This can occur due to various factors such as iodine deficiency, autoimmune disorders, or congenital defects. The primary symptoms include fatigue, weight gain, dry skin, hair loss, and depression.

Type D personality, or "distressed" personality, often observed in older people, is marked by a propensity to feel negative emotions like anxiety, depression, and stress, and to conceal these feelings in social settings. Individuals with Type D personalities may struggle to communicate their emotions and often steer clear of social engagements. This type of personality is associated with an increased risk of cardiovascular diseases and sudden cardiac death. A recent study showed that Type D personality is more prevalent in patients with hypothyroidism. The study employed a cross-sectional design, using an online survey to collect data from patients with hypothyroidism. The prevalence of Type D personality was significantly higher among patients with hypothyroidism compared to the general population (34.4% vs. 15.4%). Patients with Type D personality were more likely to experience symptoms of depression, anxiety, and fatigue, which are common comorbidities of hypothyroidism. The findings suggest that patients with hypothyroidism are more likely to exhibit Type D personality traits, which may contribute to their poorer mental health outcomes and increased symptom burden. The study underscores the importance of considering personality factors in the management and treatment of hypothyroidism, particularly in patients with comorbid mental health conditions [2].

The findings indicate that factors beyond cognitive processes influence personality development. The embodiment concept emphasizes the body's role in shaping our cognition and personality. The body schema, a subconscious level of bodily awareness, impacts how we engage with our surroundings. The bio-psycho-socio-cultural model of personality views individuals as a combination of biological, social, and cultural elements, emphasizing the interconnectedness of physical, psychological, and social factors in shaping personality.

In summary, body systems play a vital role in shaping personality by influencing our subjective experience, sense of self, emotional and sensual development, and overall well-being. The interconnectedness of bodily, psychological, and social factors is essential for understanding personality's complex and multifaceted nature.


1. Trifu SC, Tudor A, Radulescu I. Aggressive behavior in psychiatric patients in relation to hormonal imbalance (Review). Exp Ther Med. 2020 Oct;20(4):3483-3487

2. Perros P, Nagy EV, Papini E, Abad-Madroñero J, Lakwijk P, Poots AJ, Mols F, Hegedüs L. Hypothyroidism and Type D Personality: Results From E-MPATHY, a Cross-sectional International Online Patient Survey. J Clin Endocrinol Metab. 2024 Apr 9:dgae140

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