Neural activation patterns during working memory tasks and OSA disease severity: preliminary findings.
OBJECTIVE
Obstructive sleep apnea (OSA) is associated with cognitive impairments in working memory (WM). Neuronal activation during WM tasks can be indirectly assessed by blood oxygen level-dependent functional magnetic resonance imaging (BOLD-fMRI). The purpose of this study was to describe BOLD-fMRI responses during 2 separate working memory tasks and a finger tapping task in men with OSA. A secondary aim was to explore the possible relation between OSA severity (apnea/hypopnea index) and BOLD-fMRI signal patterns.


METHODS
Nine treatment-naïve men (mean age [+/- SD] of 45.7 [+/- 6.6] years) with OSA underwent BOLD fMRI testing on a research-dedicated university-based MRI scanner. During BOLD-fMRI subjects performed a Paced Auditory Serial Addition task (PASAT), an auditory N-Back task (2-BACK) task, and an alternating finger tapping.


RESULTS
PASAT and 2-BACK tasks produced similar patterns of increased bilateral activation in posterior parietal, prefrontal and cerebellar regions. BOLD signal deactivations were observed within posterior cingulate, retrosplenial and inferior frontal regions during PASAT and 2-BACK, but not during tapping. With increased disease severity, BOLD activation patterns were increased in the right parietal lobe, but decreased in the cerebellar vermis.


CONCLUSIONS
These preliminary findings suggest that the severity of OSA may correlate with neural activation during tasks of working memory, potentially reflecting compensatory neural responses in severe disease.
Archbold
Kristen H
KH
University of Arizona College of Nursing, Tucson, AZ, USA.
Borghesani
Paul R
PR
Mahurin
Roderick K
RK
Kapur
Vishesh K
VK
Landis
Carol A
CA