Frequency dependence of antidepressant response to left prefrontal repetitive transcranial magnetic stimulation (rTMS) as a function of baseline cerebral glucose metabolism.
BACKGROUND
Recent studies suggest that both high frequency (10-20 Hz) and low frequency (1 Hz) repetitive transcranial magnetic stimulation (rTMS) have an antidepressant effect in some individuals. Electrophysiologic data indicate that high frequency rTMS enhances neuronal firing efficacy and that low frequency rTMS has the opposite effect.


METHODS
We investigated the antidepressant effects of 10 daily left prefrontal 1 Hz versus 20 Hz rTMS with the hypothesis that within a given subject, antidepressant response would differ by frequency and vary as a function of baseline cerebral glucose metabolism. After baseline PET scans utilizing [18F]-Fluorodeoxyglucose, thirteen subjects participated in a randomized crossover trial of 2 weeks of 20 Hz paired with 2 weeks 1 Hz or placebo rTMS.


RESULTS
We found a negative correlation between degree of antidepressant response after 1 Hz compared to 20 Hz rTMS (r = -0.797, p < .004). Additionally, better response to 20 Hz was associated with the degree of baseline hypometabolism, whereas response to 1 Hz rTMS tended to be associated with baseline hypermetabolism.


CONCLUSIONS
These preliminary results suggest that antidepressant response to rTMS might vary as a function of stimulation frequency and may depend on pretreatment cerebral metabolism. Further studies combining rTMS and functional neuroimaging are needed.
Kimbrell
T A
TA
Biological Psychiatry Branch, National Institutes of Health, Bethesda, Maryland, Psychiatry Department, University of Arkansas, Little Rock, USA.
Little
J T
JT
Dunn
R T
RT
Frye
M A
MA
Greenberg
B D
BD
Wassermann
E M
EM
Repella
J D
JD
Danielson
A L
AL
Willis
M W
MW
Benson
B E
BE
Speer
A M
AM
Osuch
E
E
George
M S
MS
Post
R M
RM
D000328:Adult; D000368:Aged; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000473:pathology; D018592:Cross-Over Studies; D003866:Depressive Disorder / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000628:therapy*; D005260:Female; D019788:Fluorodeoxyglucose F18; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010812:Physical Stimulation / Q000379:methods; D019275:Radiopharmaceuticals; D014055:Tomography, Emission-Computed; D050781:Transcranial Magnetic Stimulation / Q000627:therapeutic use*; D016896:Treatment Outcome
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D005947:Glucose