Pattern Reversal Visual Evoked Potential and Cognitive Functions in Subclinical Hypothyroid Subjects

Area of Science:

• Neuroscience
• Endocrinology
• Ophthalmology

Background:

• Subclinical hypothyroidism (SCH) can cause early, subclinical central nervous system (CNS) involvement detectable by electrophysiological studies.
• Understanding CNS changes in SCH is crucial for early diagnosis and management.

Purpose of the Study:

• To assess visual evoked potentials (VEP), reaction time (RT), and cognitive functions in SCH patients.
• To determine the association between these neurophysiological parameters and serum thyroid-stimulating hormone (TSH) levels.

Main Methods:

• A cross-sectional study involving 36 adult SCH patients and 36 age/sex-matched euthyroid controls.
• Evaluated pattern reversal VEP, visual RT, digit spanning test, and AB clock test (ABCT).
• Analyzed group differences and correlations between variables and serum TSH levels.

Main Results:

• SCH patients exhibited statistically insignificant prolonged P100 latency in VEP compared to controls.
• A significant delay in visual reaction time (RT) was observed in SCH cases (P < 0.001).
• Digit spanning scores were significantly lower in SCH patients (P < 0.001), with lower scores associated with SCH (P = 0.027).
• Only digit spanning score showed a significant negative correlation with TSH levels (r = -0.4; P = 0.001).

Conclusions:

• Impaired working memory and delayed RT to visual stimuli indicate CNS involvement in SCH.
• VEP latency prolongation may be related to the duration of subclinical hypothyroidism.