Endocrine Abstracts

JOINT236

Objective: We aimed to evaluate the relationship between thyroid hormone levels and neurocognitive functions in patients with schizophrenia and other psychosis spectrum disorders (SSD).

Method: A total of 135 patients with early-onset SSD were included in the study. The patients were diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders-5 with schizophrenia (n = 88), schizophreniform (n = 24), schizoaffective disorder (n = 7), and other non-affective psychotic spectrum disorders (n = 16). Of the patients, 74.3% (n = 101) were within the first year of the disease duration, while 25.7% (n = 34) were within the first two years of the disease. A percentage of % 62.0 (n = 85) of our patients were experiencing their first episode of psychosis. The participants underwent a cognitive assessment. Blood samples were collected to measure serum levels of thyroid-stimulating hormone (TSH), free thyroxine (fT4), and free triiodothyronine (fT3). Subgroup analyses were conducted based on the severity of the psychosis.

Results: We found a significant interaction between The Rey Auditory Verbal Learning Test (RAVLT-learning), RAVLT-cue call, Wechsler Memory Scale (WMS), The controlled oral word association test (COWAT), Categorical fluency, Auditory Consonant Trigrams (ACT), The Trail-Making Test-A (TMT-A), global cognition, and fT4 levels. We did not find any association between all cognitive scores and fT3 and TSH levels. The correlation between fT4 levels and global cognition was significant for patients with mild to extreme illness severity (r = 0.41, P <0.001), but not significant for those with residual/minimal to mild illness (r = 0.15, P = 0.261). Accordingly, hierarchical regression analyses were performed to estimate global cognition scores, including subsamples with minimal to mild illness and youth with mild to extreme psychosis (Table 3). Education, age, sex, substance use, and daily antipsychotic dose were first entered into the models, yielding significance for both the model containing patients with minimal to mild severity as well as the model of patients with mild to extreme disease severity. When plasma fT4 levels were added in a second step, the model containing patients with minimal to mild disease severity did not provide a significant R² change (ΔR²=0.03, p=0.127), while it was significant in those with mild to extreme psychosis severity (ΔR²=0.10, p =0.002).

Conclusions: Serum fT4 levels were associated with the performance across various cognitive domains in cases of early-onset psychotic disorders. This correlation was accentuated among patients with higher illness severity. Future studies could focus on the effects of specific pathways that can affect the course and progression of psychosis.