Cognitive Status in Hypothyroid Female Patients: Event-Related Evoked Potential Study

Abstract

Aim:Higher brain functions are adversely affected in hypothyroid patients. The central nervous system features of hypothyroidism include mental retardation, various cognitive and memory deficits that have been evaluated by different neuropsychological tests. In the present study event-related potentials (ERPs) have been used to assess the cognitive status of hypothyroid patients before and after treatment. Methods: Twenty-six newly diagnosed hypothyroid female patients with a mean age of 31.85 ± 8.57 years and 26 female controls with a mean age of 30.92 ± 7.24 years were the subjects of the study. The ERPs were recorded on a computerized evoked potential recorder using the 10–20 system of electrode placement and the standard auditory ‘oddball’ paradigm. The first recording of ERPs was done at the time of diagnosis and the second recording was done 3 months after the start of treatment in a euthyroid state. Results: Prolongation of latencies was found in the early ERP components (N100, P200 and N200) in hypothyroid patients compared to controls, while no significant group differences were found on P300. In the hypothyroid group all the ERP latencies decreased significantly after attainment of euthyroidism compared to pretreatment values. ERP amplitudes revealed no significant group differences between hypothyroid patients and controls, but significant amplitude increases were found on the waves of N200 and P300 after treatment compared with pretreatment values in the hypothyroid group. Conclusions: Hypothyroid patients showed prolongation of latencies only in the early ERP components compared to controls. In hypothyroid patients, ERP findings indicate a speeding of sensory and cognitive processing in a state of euthyroidism compared to the pretreatment condition.

Thyroid Hormone Effects on Sensory Perception, Mental Speed, Neuronal Excitability and Ion Channel Regulation

“…Our present results indicate that a severe hypothyroidism of a short duration already causes significantly slowed performance in a visuo-spatial orientation task. This is in line with findings of increased latencies of event-related evoked potentials in hypothyroidism (97,98).…”

“…The incidence of decreases in hearing threshold observed in hypothyroid patients varies from study to study, ranging from 85% (28), 80% (29), 62% (120), 55% (121) 43% (122), 31% (80) to as low as 12% [98].…”

P300 as an auxiliary method in clinical practice: A review of literature

“…Moreover, with P300 testing, damage of cognitive functions resulting from taking different medicines, especially antiepileptic drugs, can also be monitored (61)(62)(63). Additionally, P300 characteristics help diagnosing cognitive damage resulting from systemic diseases, such as anaemia, uremia (renal insufficiency), hepatic encephalopathy, systemic lupus erythematosus, diabetes mellitus, hypothyreosis, as well as COPD (64)(65)(66)(67)(68)(69)(70)(71)(72)(73)(74)(75)(76). Moreover, cognitive function damage in patients with HIV-1 neurologically asymptomatic seropositive can be assessed with P300 testing (78).…”

“…Cognitive damage in some systemic diseases can be assessed with CEP P300 (64)(65)(66)(67)(68)(69)(70)(71)(72)(73)(74)(75)(76)(77)(78). Improvements in the treatment and recovery can be followed in the same way.…”

Reversible Cognitive, Motor, and Driving Impairments in Severe Hypothyroidism

“…Anxiety and particularly depression have been seen in hypothyroid patients in several studies (19,20,22,23). Delayed auditory and visual event-related potentials, indicators of disrupted central sensory processing, have also been found in hypothyroidism, although not always consistently with respect to early versus delayed peaks (24,25). Nonetheless, reversible decreased phosphorus energy metabolism has been previously demonstrated in the frontal lobes of hypothyroid patients evaluated in a similar study design (26), revealing alterations in brain biochemistry that corroborate this current study.…”