Resource Material

The Thyroid and the Mind and Emotions/Thyroid Dysfunction and Mental Disorders

A.G. Awad, MD, BCH, PhD, FRCP(C)
Associate Professor of Psychiatry, University of Toronto
Director, Psychobiological Medicine Unit, Department of Psychiatry, Toronto Western Hospital

The Thyroid and the Mind and Emotions

Summary of an address to the Kitchener-Waterloo Area Chapter

The psychiatric disturbances which accompany hyperthyroidism and hypothyroidism, the two commonest thyroid disorders, mimic mental illness. People with an overactive thyroid may exhibit marked anxiety and tension, emotional lability, impatience and irritability, distractible overactivity, exaggerated sensitivity to noise, and fluctuating depression with sadness and problems with sleep and the appetite. In extreme cases, they may appear schizophrenic, losing touch with reality and becoming delirious or hallucinating. An underactive thyroid can lead to progressive loss of interest and initiative, slowing of mental processes, poor memory for recent events, fading of the personality’s colour and vivacity, general intellectual deterioration, depression with a paranoid flavour, and eventually, if not checked, to dementia and permanent harmful effects on the brain. In instances of each condition, some persons have been wrongly diagnosed, hospitalized for months, and treated unsuccessfully for psychosis.

Detection of the thyroid problem is complicated by the fact that everyone feels anxiety and tension to some degree, that many thyroid symptoms are similar to those of other diseases, and that hypothyroidism in particular often develops insidiously over a considerable time. But the results of overlooking the thyroid can be serious. It is very important for the physician to explore fully and give the tests for thyroid dysfunction, which today are relatively simple. When effective thyroid treatment is begun, the general response is quite favorable. Vitality returns and the mental processes become efficient again. If there is a residue of emotional difficulties, it may be related not to the thyroid gland but to other aspects of life.

The question arises: since thyroid hormone therapy is so rewarding for patients who have depression associated with a malfunctioning thyroid, would it also benefit those who have normal thyroid function? The answer is not yet clear, though it has helped some who did not respond to anti-depressants.

Nor is the relationship clear between stress and the thyroid. The number of people who cite unusually stressful experiences before the onset of hyperthyroidism seems to bear out the theory of stress as a precipitating factor. While others can come through the same upheavals without developing thyroid disease, some perhaps are predisposed to it. On the other hand, it can be argued that the illness itself, before its symptoms are manifested, is contributing to the situation of stress.

The physician must also be careful to check the thyroid in cases where psychiatric medications must be taken over a long period. Lithium, the drug commonly used to stabilize the moods and increase the efficiency of manic-depressives, can cause hypothyroidism, particularly in middle-aged women who are the most susceptible to this trouble; the hypothyroidism in its turn can produce depression, the very problem that the treatment was intended to relieve.


Thyroid Dysfunction and Mental Disorders

Summary of an address to the Metropolitan Toronto Chapter

The relationship between psychiatry and thyroid dysfunction has attracted a good deal of attention for the following reasons:

  1. Thyroid disorders, such as hyperthyroidism or hypothyroidism, can be accompanied by prominent mental abnormalities.
  2. Thyroid hormones have been used in the treatment of certain psychiatric conditions.
  3. Some drugs used for the treatment of mental illness can have an effect on the thyroid gland.

Mental Abnormalities and Thyroid Disorders

Attention has been directed to the possible role of stress or emotional disturbance in precipitating hyperthyroidism. Although hyperthyroidism may follow some emotional upheaval or stressful event, the possibility exists that the emotional upheaval prior to the illness may have been the by-product of the early phase of thyroid hyperactivity itself before the complete picture of the illness becomes manifested. Similarly, the psychological constitution of those who develop the illness has been extensively studied, but with no good consensus between various personality descriptions given. I believe the role of personality factors has been overemphasized. Psychological disturbances are quite common with thyroid hyperactivity and can be part of the early picture:

  • marked anxiety and tension
  • emotional lability
  • irritability and impatience
  • distractible overactivity
  • exaggerated sensitivity to noise
  • fluctuating depression

More serious mental disturbances which used to accompany “thyroid crisis”, such as acute psychotic episodes, delirium and fever are rarely seen these days as a result of the improved detection of the illness and availability of effective treatment.

In general, the psychological disturbances show satisfactory resolution with adequate treatment of the thyroid hyperactivity.

Since hypothyroidism usually develops slowly, and the early complaints are frequently minor, vague and diffuse in nature, it is not surprising that the diagnosis is often overlooked. However, the physical changes that accompany the illness are characteristic: dry, rough skin; pale and puffy complexion; loss of hair; change in voice; decreased appetite, etc.

Psychological symptoms are common and well manifested by the time the patient seeks medical advice. Not infrequently, psychological disturbances are the main complaints that bring hypothyroid patients to the psychiatrist first:

  • marked slowing of all mental processes
  • progressive loss of initiative and interest
  • memory difficulties
  • thinking is easily muddled
  • general intellectual deterioration
  • depression with paranoid flavour
  • organic psychosis

In severe, untreated cases, dementia may be the ultimate outcome. This underscores the importance of early detection and treatment.

Use of Thyroid Hormones in Treatment of Mental Illness
It is claimed that in the treatment of depression not related to any thyroid disturbance the addition of thyroxine may hasten and augment the effects of antidepressant drugs. Thyroxine was also found to be beneficial in the treatment of a rare condition call periodic catatonia in which the patient’s condition alternates periodically between states of apathy and immobility and marked excitement.

Effects of Psychiatric Drugs on the Thyroid Gland
Lithium, a natural element drug used successfully to treat manic-depressive illness and prevent relapse, was found to produce a state of hypothyroidism in some patients. This side effect is not universal and happens only after long-term use. Middle-aged women seem to be more vulnerable to this complication. This underscores the importance of regular monitoring of thyroid function during long-term lithium therapy.

In conclusion, disturbance of thyroid function may be accompanied by psychological disturbances which can mimic other psychiatric syndromes. Hence, early detection and treatment of the thyroid disturbance, as well as appropriate attention to the emotional and psychological condition of the patient, cannot be overemphasized.

Reprinted from Thyrobulletin, Vol. 7, No. 3

Reviewed 2000

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