Effect of CPAP therapy on C-reactive protein and cognitive impairment in patients with obstructive sleep apnea hypopnea syndrome

Obstructive sleep apnea hypopnea syndrome (OSAHS) is associated with neurocognitive impairment. We examined the role of the systemic inflammatory response, measured by high-sensitivity C-reactive protein (hsCRP) assay, and the effect of CPAP treatment on hsCRP and cognitive impairment in patients with OSAHS. Eligible subjects (n = 178) were categorized into two groups: absent or mild OSAHS, and moderate to severe OSAHS. First, the Montreal Cognitive Assessment (MoCA) and serum hsCRP concentration were measured. Then, the moderate to severe OSAHS group was further divided into a conservative treatment subgroup (n = 68) and a CPAP subgroup (n = 68). After 6 months of treatment, MoCA scores and hsCRP concentrations were re-measured in the moderate to severe group. Compared with the absent or mild OSAHS group, hsCRP concentration was higher (1.00 +/- 1.28 mg/L versus 2.71 +/- 1.8, p < 0.001) and MoCA scores were significantly lower (27.4 +/- 1.4 versus 26.3 +/- 2.0, p < 0.001) in the moderate to severe group. After adjustment for age, education, body mass index, and neck circumference, hsCRP and MoCA scores correlated with parameters of overnight hypoxia. hsCRP and the proportion of time spent with blood oxygen saturation < 90 % (T90) predicted MoCA score. hsCRP and MoCA score improved, and the subdomains of the MoCA were partially improved, in the CPAP treatment subgroup. In conservatively managed patients, hsCRP concentration increased, and there was no improvement in neurocognitive dysfunction, with the memory subdomain significantly worse. hsCRP may play a role in neurocognitive dysfunction in OSAHS. Long-term CPAP treatment could normalize the serum hsCRP concentration and partially reverse cognitive dysfunction in OSAHS.