Abstract
Background
Affective disorders may affect patients’ time perception. Several studies have described
time as a function of the frontal lobe. The activating effects of vagus nerve stimulation
on the frontal lobe might also modulate time perception in patients with major depressive
disorder (MDD).
Methods
Time perception was investigated in 30 patients with MDD and in 7 patients with therapy-resistant
MDD. In these 7 patients, a VNS system was implanted and time perception was assessed
before and during stimulation. A time estimation task in which patients were asked
“How many seconds have passed?” tested time perception at 4 defined time points (34 s,
77 s, 192 s and 230 s). The differences between the estimated and actual durations
were calculated and used for subsequent analysis.
Results
Patients with MDD and healthy controls estimated the set time points relatively accurately.
A general linear model revealed a significant main effect of group but not of age
or sex. The passing of time was perceived as significantly slower in patients undergoing
VNS compared to patients with MDD at all time points (T34: t=−4.2; df=35; p<0.001;
T77: t=−4.8; df=35; p<0.001; T192: t=−2.0; df=35; p=0.059; T230 t=−2.2; df=35; p=0.039)
as well as compared to healthy controls (at only T77: t=4.1; df=35; p<0.001). There
were no differences in time perception with regard to age, sex or polarity of depression
(uni- or bipolar).
Conclusions
VNS is capable of changing the perception of time. This discovery furthers the basic
research on circadian rhythms in patients with psychiatric disorders.
Key words
major depressive disorder (MDD) - subjective time perception - vagus nerve stimulation
(VNS)