Low-resolution brain electromagnetic tomography (LORETA) identifies brain regions linked to psychometric performance under modafinil in narcolepsy

Saletu, Michael; Anderer, Peter; Semlitsch, Heribert V.; Saletu-Zyhlarz, Gerda Maria; Mandl, Magdalena; Zeitlhofer, Josef; Saletu, Bernd

doi:10.1016/j.pscychresns.2006.04.005

« Previous Next »Psychiatry Research: Neuroimaging
Volume 154, Issue 1 , Pages 69-84, 15 January 2007

Low-resolution brain electromagnetic tomography (LORETA) identifies brain regions linked to psychometric performance under modafinil in narcolepsy

Michael Saletu
- Department of Neurology, Medical University of Vienna, Vienna, Austria
Peter Anderer
- Department of Psychiatry, Medical University of Vienna, Vienna, Austria
Heribert V. Semlitsch
- Department of Psychiatry, Medical University of Vienna, Vienna, Austria
Gerda Maria Saletu-Zyhlarz
- Department of Psychiatry, Medical University of Vienna, Vienna, Austria
Magdalena Mandl
- Department of Psychiatry, Medical University of Vienna, Vienna, Austria
Josef Zeitlhofer
- Department of Neurology, Medical University of Vienna, Vienna, Austria
Bernd Saletu
- Department of Psychiatry, Medical University of Vienna, Vienna, Austria
- Corresponding author. Section of Sleep Research and Pharmacopsychiatry, Department of Psychiatry, Medical University of Vienna, Währinger Gürtel 18-20, A-1090 Vienna, Austria. Tel.: +43 1 40400 3637/3683; fax: +43 1 4025909.

Received 11 January 2006; received in revised form 15 March 2006; accepted 2 April 2006.

Abstract

Low-resolution brain electromagnetic tomography (LORETA) showed a functional deterioration of the fronto-temporo-parietal network of the right hemispheric vigilance system in narcolepsy and a therapeutic effect of modafinil. The aim of this study was to determine the effects of modafinil on cognitive and thymopsychic variables in patients with narcolepsy and investigate whether neurophysiological vigilance changes correlate with cognitive and subjective vigilance alterations at the behavioral level. In a double-blind, placebo-controlled crossover design, EEG-LORETA and psychometric data were obtained during midmorning hours in 15 narcoleptics before and after 3 weeks of placebo or 400 mg modafinil. Cognitive investigations included the Pauli Test and complex reaction time. Thymopsychic/psychophysiological evaluation comprised drive, mood, affectivity, wakefulness, depression, anxiety, the Symptom Checklist 90 and critical flicker frequency. The Multiple Sleep Latency Test (MSLT) and the Epworth Sleepiness Scale (ESS) were performed too. Cognitive performance (Pauli Test) was significantly better after modafinil than after placebo. Concerning reaction time and thymopsychic variables, no significant differences were observed. Correlation analyses revealed that a decrease in prefrontal delta, theta and alpha-1 power correlated with an improvement in cognitive performance. Moreover, drowsiness was positively correlated with theta power in parietal and medial prefrontal regions and beta-1 and beta-2 power in occipital regions. A less significant correlation was observed between midmorning EEG LORETA and the MSLT; between EEG LORETA and the ESS, the correlation was even weaker. In conclusion, modafinil did not influence thymopsychic variables in narcolepsy, but it significantly improved cognitive performance, which may be related to medial prefrontal activity processes identified by LORETA.

Keywords: Sleepiness, Psychostimulant, Electroencephalography, Cognition, Prefrontal activity