Psychiatric and cognitive manifestations of hypothyroidism

Overt hypothyroidism has major effects on neuropsychiatric function, but patients with mild hypothyroidism may attribute unrelated neuropsychiatric symptoms to their thyroid condition. This review will summarize data on neuropsychiatric effects of hypothyroidism, and provide guidelines regarding the relationship between hypothyroidism and neuropsychiatric issues, and treatment indications. Clinical investigations and functional imaging studies confirm that overt hypothyroidism is associated with affective and cognitive decrements, largely reversible with treatment. In contrast, subclinical hypothyroidism is not associated with major neuropsychiatric deficits, although studies utilizing sensitive measures show small deficits in memory and executive function. Neuropsychiatric complaints are more common when patients are aware of their thyroid disease, regardless of their thyroid function at the time of testing. Neuropsychiatric dysfunction is common in overt hypothyroidism and will improve (perhaps not completely resolve) with therapy. Deficits related to thyroid dysfunction are usually mild in subclinical hypothyroidism, and realistic expectations need to be set regarding symptom reversibility with treatment. Patients with mild hypothyroidism and significant distress related to neuropsychiatric symptoms, most likely, have independent diagnoses that should be evaluated separately.