The effect of CPAP therapy on insulin-like growth factor and cognitive functions in obstructive sleep apnea patients

Cognitive impairment is common among patients with obstructive sleep apnea syndrome (OSAS). In this study, we aimed to investigate the effect of continuous positive airway pressure (CPAP) therapy on serum insulin-like growth factor-1 (IGF-1) levels and cognitive functions in patients with OSAS.

Thirty-three patients with newly diagnosed OSAS and 17 healthy-control subjects enrolled in the study. All individuals completed the mini-mental state examination (MMSE) to evaluate cognitive function. Blood samples were taken at the end of the polysomnography in the morning and the same procedures were repeated 3 months after starting CPAP treatment.

In the OSAS group, the baseline MMSE score was 23.5 ± 3.6, and serum IGF-1 level was 79.1 ± 36.1 ng/mL. Both values were significantly lower compared with the control group (mean MMSE score = 28.1 ± 1.4, P = 0.0001; mean serum IGF-1 level = 147.1 ± 49.1 ng/mL, P < 0.0001). Three months after CPAP treatment, OSAS patients showed a significant improvement in MMSE scores (26.5 ± 2.8, P = 0.0001) and serum IGF-1 level (129.1 ± 58.2, P = 0.0001). In contrast, baseline and third-month measurements for IGF-1 levels and MMSE scores were not significantly different in the control group.

The results indicate that effective CPAP therapy in OSAS patients leads to significant improvement in cognitive functions and IGF-1 even in a short-term follow-up. Cognitive function assessment might be a part of evaluation in OSAS patients.