Introduction: Cognitive problems in patients with obstructive sleep apnea have been suspected since the 1980s. Several studies have investigated different cognitive domains. A similar widespread survey has not been done in the Bulgarian population.

Aim: This study aimed to evaluate global cognitive functioning and memory function in patients with obstructive sleep apnea and to examine the potential influence of comorbidities on cognitive functions.

Materials and methods: The study examined the neurocognitive profile of 103 consecutive patients newly diagnosed with OSA and 31 healthy controls. A list of inclusion and exclusion criteria was developed. Sleep breathing was examined in both groups. The other methods were: a medical history of patients, clinical examination, neuropsychological assessment, statistical analysis.

Results: The study found that the global cognitive functioning of patients with OSA and the memory function was impaired. Short-term memory has been found affected predominantly. Only obesity was distinguished as a major factor relevant to the severity of cognitive changes in the study group. A statistically significant difference between the groups with and without obesity was found for the applied memory tests, except for the delayed recall and word recognition. The duration of exposure to hypoxia and sleep fragmentation is important for the severity of cognitive deficits. The results confirmed this theory showing that this factor is among the major severity factors.

Conclusion: The study found that the global cognitive functioning of patients with OSA, as well as memory function, were impaired. The role of comorbidities is complex and far from clear.