Event-related brain potentials in patients with hypothyroidism.

Objective: To evaluate the cognitive function of patients with hypothyroidism, based on long-latency auditory event-related potentials (ERPs).

Methods: We investigated alterations of P300 latency in patients with hypothyroidism before treatment and after restoration of euthyroidism. ERPs were elicited in 14 untreated patients with hypothyroidism (mean age, 26.71 +/- 2.39 years) and in a group of 30 control subjects with comparable mean age, sex distribution, and educational level. ERP recordings were repeated at 1 and 6 months after attainment of euthyroidism.

Results: Untreated patients with hypothyroidism had longer P300 and N1 wave latencies in comparison with those in the control subjects (P = 0.003 and P = 0.018, respectively). The mean P300 latencies did not change significantly 1 month after restoration of euthyroidism. At 6 months after attainment of euthyroidism, however, the mean P300 latencies returned to normal values, similar to those in the control subjects.

Conclusion: We conclude that P300 latencies are impaired in patients with hypothyroidism, which is indicative of cognitive dysfunction. These alterations, however, may be reversed 6 months after attainment of euthyroidism.