Background: Olfactory and gustatory functions were investigated before and during vagus nerve stimulation (VNS) in a group of 9 patients with therapy-resistant depression, implanted with a VNS system.
Methods: Gustation and olfaction were tested using standard sniffing tests. Subjects participated in 2 sessions with the vagal stimulator switched on and off, respectively.
Results: Under conditions of stimulation of the VNS, there were statistically significant differences of the threshold of perception, with an intensification of the taste “sweet” (Z=−2.0; p=0.048) and “bitter” (Z=−2.5; p=0.011) compared to the “off-mode”. A statistical trend (Z=−1.7; p=0.098) for increased intensity of the taste “salty” was observed, however, these results would supposedly disappear after correction for multiple testing presumably due to the large number of variables and the small sample size. There were no statistically relevant differences concerning olfactory perception.
Conclusions: The changes of gustatory perception under conditions of vagal nerve stimulation observed in this study show another important central nervous effect of vagal stimulation on the limbic system that might be of importance in the elucidation of mechanisms of action of VNS especially on refractory depression.
References
1
Kennedy SH, Giacobbe P.
Treatment resistant depression – advances in somatic therapies.
Ann Clin Psychiatry.
2007;
19
279-287
3
Groves DA, Brown VJ.
Vagal nerve stimulation: a review of its applications and potential mechanisms that mediate its clinical effects.
Neurosci Biobehav Rev.
2005;
29
493-500
4
Bajbouj M, Merkl A, Schlaepfer TE. et al .
Two-year outcome of vagus nerve stimulation in treatment-resistant depression.
J Clin Psychopharmacol.
2010;
30
273-281
5
Sperling W, Kornhuber J, Wiltfang J. et al .
Combined VNS-rTMS treatment in a patient with therapy resistant depression.
Pharmacopsychiatry.
2007;
40
39-40
6
Sperling W, Reulbach U, Maihofner C. et al .
Vagus nerve stimulation in a patient with Gilles de la Tourette syndrome and major depression.
Pharmacopsychiatry.
2008;
41
117-118
7
Manta S, Dong J, Debonnel G. et al .
Enhancement of the function of rat serotonin and norepinephrine neurons by sustained vagus nerve stimulation.
J Psychiatry Neurosci.
2009;
34
272-280
8
Sperling W, Reulbach U, Bleich S. et al .
Cardiac effects of vagus nerve stimulation in patients with major depression.
Pharmacopsychiatry.
2010;
43
7-11
11
Wang H, Chen X, Lin Z. et al .
Long-term effect of vagus nerve stimulation on interictal epileptiform discharges in refractory epilepsy.
J Neurol Sci.
2009;
284
96-102
12
Vonck K, De Herdt V, Boon P.
Vagal nerve stimulation – a 15-year survey of an established treatment modality in epilepsy surgery.
Adv Tech Stand Neurosurg.
2009;
34
111-146
14
Lomarev M, Denslow S, Nahas Z. et al .
Vagus nerve stimulation (VNS) synchronized BOLD fMRI suggests that VNS in depressed adults has frequency/dose dependent effects.
J Psychiatr Res.
2002;
36
219-227
15
Henry TR, Bakay RA, Pennell PB. et al .
Brain blood-flow alterations induced by therapeutic vagus nerve stimulation in partial epilepsy: II. prolonged effects at high and low levels of stimulation.
Epilepsia.
2004;
45
1064-1070
18
Garcia-Diaz DE, Aguilar-Baturoni HU, Guevara-Aguilar R. et al .
Vagus nerve stimulation modifies the electrical activity of the olfactory bulb.
Brain Res Bull.
1984;
12
529-537
19
Ruggiero DA, Anwar S, Kim J. et al .
Visceral afferent pathways to the thalamus and olfactory tubercle: behavioral implications.
Brain Res.
1998;
799
159-171
27
Dichter GS, Smoski MJ, Kampov-Polevoy AB. et al .
Unipolar depression does not moderate responses to the sweet taste test.
Depress Anxiety.
2010;
27
589-563
28
Zunszain PA, Anacker C, Cattaneo A. et al .
Glucocorticoids, cytokines and brain abnormalities in depression.
Prog Neuropsychopharmacol Biol Psychiatry.
2010 Apr 18;
[Epub ahead of print]
29
Pagani M, Salmaso D, Nardo D. et al .
Imaging the neurobiological substrate of atypical depression by SPECT.
Eur J Nucl Med Mol Imaging.
2007;
34
110-120
30
Ballmaier M, Toga AW, Blanton RE. et al .
Anterior cingulate, gyrus rectus, and orbitofrontal abnormalities in elderly depressed patients: an MRI-based parcellation of the prefrontal cortex.
Am J Psychiatry.
2004;
161
99-108
