Evaluation of cognitive functions in subclinical hypothyroidism by event related potentials/Subklinik hipotiroidizmde bilissel islevlerin olay iliskili potansiyeller ile degerlendirilmesi

Objective: The cognitive impairment in overt hypothyroidism such as slowed information processing speed, reduced efficiency in executive functions and poor learning, are well supported by previous studies. The degree to which subclinical hypothyroidism affects the cognitive functions remains controversial. In this study, we aimed to assess the cognitive impairment in the subclinical hypothyroid patients by using event related potentials. Method: Fifteen subclinical hypothyroid patients (normal T3 and T4 levels with elevated TSH levels) and age matched 20 healthy individuals were recruited into the study. Cognition (speed of information processing, cognition processing capacity and perceptual processing resources) was studied using the techniques of auditory event-related potentials (P300 latency and amplitude) which were recorded from 6 EEG leads in an odd-ball paradigm. Results: The P200, N200 and P300 latencies and amplitudes of both groups showed no significant difference (p>0.05). No correlation was found between thyroid hormones and P300 latencies. Conclusion: There are contradictory results about the cognitive impairment in subclinical hypothyroidism. Our study revealed that subclinical hypothyroidism does not impair cognitive processes measured by the P300 study. New studies comprising a large number of patients are needed to clarify the issue. Key words: Hypothyroidism, cognition, event related potentials, P300 Amac: Asikar hipotiroidizmde yavaslamis bilgi degerlendirme hizi, yurutucu islevlerde azalmis etkinlik ve ogrenme yeteneginde zayiflama gibi bilissel yetersizlik olabilecegi yapilmis calismalarda gosterilmistir. Subklinik hipotiroidizmin ise bilissel islevleri ne derece etkiledigi belirsizdir. Bu calismada subklinik hipotiodizmi olan hastalarda olay iliskili potansiyeller kayitlanarak bilissel yetilerdeki degisikligin belirlenmesi amaclandi. Yontem: Calismaya 15 subklinik hipotiroidisi olan (normal T3 ve T4 hormon duzeyleri ile birlikte yuksek TSH duzeyi) ve yasca eslenmis 20 saglikli birey alindi. Olgulara bilgi degerlendirme hizi, bilissel degerlendirme kapasitesi ve algi yetenegi gibi bilissel yetilerin olculebilmesi acisindan yeterliligi gosterilmis olan, isitsel olay iliskili potansiyel kayitlamasi (P300 amplitud ve latansi) yapildi. Kayitlama "odd-ball" paradigmasi ile 6 EEG elektrodu uzerinden gerceklestirildi. Bulgular: Iki grubun P200, N200 and P300 latans ve amplitudleri arasinda anlamli bir fark gozlenmedi (p>0.05). Tiroid hormonl