The study presents research results on the effect of thyroid hormones on cognitive function in patients with thyroid diseases. The study highlighted the mechanisms of the development of cognitive disorders in these patients, which include altered neurotransmission processes and expression of genes responsible for the proliferation of neurons and glial cells, bloodbrain barrier dysfunction, decreased plasticity of neurons, and damage to brain tissue repair systems, which allows for identifying new therapeutic strategies for the treatment of cognitive disorders. Thyroid metabolism disorders are manifested by numerous symptoms, including those associated with cognitive deficits. Thus, the true cause of the disease must be identified, since the correction of thyroid hormone levels will lead to symptom regression, whereas symptomatic treatment is not always effective and may worsen the course of the underlying disease. In patients from different age groups, thyroid dysfunction is one of the causes of cognitive impairment. Cognitive decline, dysphoria, and depression are the most common in hypothyroidism, and thyrotoxicosis is accompanied by symptoms of arousal, mood lability, psychosis, and apathy. Cognitive impairment negatively affects the quality of life of patients, worsens treatment adherence, and can promote the development of acute and chronic complications associated with thyroid diseases. An equally important problem is the insufficiency of objective criteria for the verification of cognitive impairment and the lack of effective treatment methods and consequently the late and ineffective implementation of therapeutic measures. In general, thyroid dysfunction is accompanied by various neurocognitive disorders, and severity depends on sex and the etiology, duration, and severity of the disease. Correction of thyroid metabolism disorders does not always eliminate cognitive impairments; therefore, a multidisciplinary approach is needed, with the participation of not only endocrinologists but also specialists in neuropsychiatric profile. Further research on the pathogenesis of cognitive disorders in thyroid dysfunction will allow for identifying new therapeutic strategies aimed at early detection and correction of cognitive deficits, reducing the risk of neurodegenerative processes, and ultimately will reduce the treatment and rehabilitation time.