Aims: The loudness dependence of auditory evoked potentials (LD) has been suggested as
a marker of central monoaminergic function. A strong LD is associated with a reduction
of central serotonergic activity and a favorable response to serotonergic agents in
patients with depression. In combined neurophysiological and nuclear imaging studies
the LD was correlated with both central serotonin and dopamine transporter availability.
Aim of this study was to investigate the long-term effects of serotonergic versus
noradrenergic antidepressants on LD in patients with depression.
Methods: Patients with major depressive episodes were included into a 4-week treatment study
with either the noradrenergic antidepressant reboxetine (reb) or the serotonergic
agent citalopram (cit). Neurophysiological and clinical assessments (HAM-D scores)
were performed both at baseline and under medication.
Results: 90 patients [44 cit, 46 reb] were prospectively investigated. Baseline-LD and -HAM-D
scores did not differ significantly between the groups. Under medication there was
no significant change in LD in neither group, nor were there significant differences
between the groups.
Conclusion: Serotonergic or noradrenergic medication do not seem to significantly or differentially
alter the LD in depressed patients. Implications of these results regarding central
monoaminergic function both at baseline and under treatment will be discussed.
