Evidence for cognitive resource imbalance in adolescents with narcolepsy.
The study investigated brain activity changes during performance of a verbal working memory task in a population of adolescents with narcolepsy. Seventeen narcolepsy patients and twenty healthy controls performed a verbal working memory task during simultaneous fMRI and EEG acquisition. All subjects also underwent MRS to measure GABA and Glutamate concentrations in the medial prefrontal cortex. Activation levels in the default mode network and left middle frontal gyrus were examined to investigate whether narcolepsy is characterized by an imbalance in cognitive resources. Significantly increased deactivation within the default mode network during task performance was observed for the narcolepsy patients for both the encoding and recognition phases of the task. No evidence for task performance deficits or reduced activation within the left middle frontal gyrus was noted for the narcolepsy patients. Correlation analyses between the spectroscopy and fMRI data indicated that deactivation of the anterior aspect of the default mode in narcolepsy patients correlated more with increased concentrations of Glutamate and decreased concentrations of GABA. In contrast, deactivation in the default mode was correlated with increased concentrations of GABA and decreased concentrations of Glutamate in controls. The results suggested that narcolepsy is not characterized by a deficit in working memory but rather an imbalance of cognitive resources in favor of monitoring and maintaining attention over actual task performance. This points towards dysregulation within the sustained attention system being the origin behind self-reported cognitive difficulties in narcolepsy.
Center for Medical Image Science and Visualization (CMIV), Linköping University, Linköpings universitet/US, SE-581 85, Linköping, SE, Sweden. suzanne.witt@liu.se.
Suzanne T
ST
Witt
Center for Medical Image Science and Visualization (CMIV), Linköping University, Linköpings universitet/US, SE-581 85, Linköping, SE, Sweden.|Department of Medical and Health Sciences (IMH), Linköping University, Linköping, Sweden.
Natasha Morales
NM
Drissi
Center for Medical Image Science and Visualization (CMIV), Linköping University, Linköpings universitet/US, SE-581 85, Linköping, SE, Sweden.|Radiation Physics, Department of Medical and Health Sciences, Linköping University, Linköping, Sweden.
Sofie
S
Tapper
Linnaeus Center HEAD, Linköping University, Linköping, Sweden.
Anna
A
Wretman
Department of Pediatrics, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
Attila
A
Szakács
Department of Pediatrics, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
Tove
T
Hallböök
Center for Medical Image Science and Visualization (CMIV), Linköping University, Linköpings universitet/US, SE-581 85, Linköping, SE, Sweden.|Department of Neurology, Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden.|Department of Neuroscience and Neurology, Uppsala University, Uppsala, Sweden.
Anne-Marie
AM
Landtblom
Center for Medical Image Science and Visualization (CMIV), Linköping University, Linköpings universitet/US, SE-581 85, Linköping, SE, Sweden.|Linnaeus Center HEAD, Linköping University, Linköping, Sweden.|Department of Behavioral Sciences and Learning, Linköping University, Linköping, Sweden.
Thomas
T
Karlsson
Center for Medical Image Science and Visualization (CMIV), Linköping University, Linköpings universitet/US, SE-581 85, Linköping, SE, Sweden.|Radiation Physics, Department of Medical and Health Sciences, Linköping University, Linköping, Sweden.|Radiology, Department of Medical and Health Sciences, Linköping University, Linköping, Sweden.
Peter
P
Lundberg
Center for Medical Image Science and Visualization (CMIV), Linköping University, Linköpings universitet/US, SE-581 85, Linköping, SE, Sweden.|Department of Medical and Health Sciences (IMH), Linköping University, Linköping, Sweden.
Maria
M
Engström
D000293:Adolescent; D001921:Brain / Q000000981:diagnostic imaging / Q000503:physiopathology*; D003071:Cognition / Q000502:physiology*; D004569:Electroencephalography; D005260:Female; D018698:Glutamic Acid / Q000378:metabolism; D006801:Humans; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D009290:Narcolepsy / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000523:psychology*; D009434:Neural Pathways / Q000000981:diagnostic imaging / Q000503:physiopathology; D013060:Speech / Q000502:physiology; D013067:Speech Perception / Q000502:physiology; D055815:Young Adult; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid
EEG; GABA; MRS; Narcolepsy; Working memory; fMRI