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ABSTRACT
Anxiety disorders are among the most diagnosed psychiatric disorders in the
adolescent population. These disorders are often accompanied by different
comorbidities, such as sleep problems. The main objective of this thesis is to
characterize the cortical activity during wake and sleep, using quantified EEG, in a
population of adolescents presenting an anxiety disorder, and to compare these results
to those of a control group of adolescents. Secondly, we wish to verify if the EEG
activity of the anxious participants correlates with different clinical measures.
Two different studies are conducted in order to attain our objectives, the first one
being on the EEG activity during wake, and the second being on the EEG activity
during sleep (slow wave sleep and rapid eye movement sleep). The first study reveals
that the EEG activity from both groups does not differ in the evening. However, in
the morning, anxious participants display an increased activity on central electrodes
(0.75-10 Hz and 13-20 Hz), and on occipital electrodes (2.5-7.75 Hz). In the second
study, we demonstrate that anxious participants show an increased absolute EEG
activity on central electrodes: in slow wave sleep (stages 3 and 4), it is found on all
frequency bands, in stage 2, it is found on the theta, alpha and beta frequency bands.
Finally, in rapid eye movement sleep, the differences are only in alpha and beta, and
not in theta and delta. These data suggest the impairment of thalamo-cortical gating
mechanisms in adolescents with anxiety disorders, leading to CNS hyperarousal.
As for the correlations between the EEG activity and the clinical measures, the results
from our studies reveal that the slow frequencies (theta and delta) of morning wake