[Interactions between brain, psyche and thyroid]

Interactions between brain, psyche and thyroid are known from historical descriptions of thyroidectomy (Kocher) and hyperthyroidism. However, their importance is often underscored in clinical routine. Thyroid hormone deficiency during pregnancy may result in irreversible mental retardation and requires levothyroxine substitution. TSH screening after delivery must identify newborns with congenital hypothyroidism: An early levothyroxine substitution and long term therapy control are required. Hypothyroidism and depression have many symptoms in common. Cognitive deficits and depressive states are often found in overt hypothyroidism, psychotic derangements are rare. Levothyroxine improves hypothyroid symptoms and mental performance, mood and motivation. Psychic symptoms of hyperthyroidism include agitation, irritability, mood disturbances, hyperactivity, anxiousness and even panic attacks. Manic and delusional states are rare. In geriatric patients hyperthyroidism may be oligosymptomatic. In psychiatric patients more frequent but unspecific disturbances of thyroid laboratory values being reversible without specific therapy have to be distinguished from rather rare but causative organic thyroid diseases with therapeutic consequences. Some psychiatric drugs influence thyroid laboratory results. Hypothyroidism in depressive patients is a negative prognostic parameter and requires therapy. Psychiatric symptoms associated with hypothyroidism are usually reversible under levothyroxine within 4-8 weeks. The standard for hypothyroidism is mono-levothyroxine therapy.