Electrophysiological differences between high and low frequency rTMS protocols in depression treatment.

Area of Science:

• Neuroscience
• Psychiatry
• Medical Technology

Background:

• Repetitive transcranial magnetic stimulation (rTMS) is a growing treatment for drug-resistant depression.
• The precise neurophysiological mechanisms underlying rTMS efficacy remain unclear, hindering optimal parameter selection and treatment evaluation.
• Understanding these mechanisms is crucial for improving rTMS therapy in psychiatry.

Purpose of the Study:

• To compare the influence of high-frequency (10 Hz) and low-frequency (1 Hz) rTMS protocols on EEG band power.
• To assess the relationship between electrophysiological changes and clinical outcomes (MADRS, BDI, HAM-D17 scores).
• To elucidate the distinct neurophysiological mechanisms of different rTMS protocols.

Main Methods:

• Forty-five patients with depression received either 10 Hz or 1 Hz rTMS daily for 10-15 sessions.
• Electroencephalography (EEG) band power spectrum and clinical scores were recorded before and after the rTMS course.
• Statistical analysis compared the effects of the two protocols on EEG data and clinical outcomes.

Main Results:

• Both protocols led to significant clinical improvement in a majority of patients, with no significant difference in score reduction between groups.
• High-frequency (10 Hz) rTMS induced widespread EEG changes, including increased delta and theta power and altered alpha power distribution.
• Low-frequency (1 Hz) rTMS showed minimal impact on basic EEG power but caused a significant shift in frontal alpha asymmetry, which correlated with clinical improvement.

Conclusions:

• High-frequency (10 Hz) and low-frequency (1 Hz) rTMS protocols exhibit different neurophysiological mechanisms.
• Low-frequency rTMS specifically influences frontal alpha asymmetry, linking it to clinical outcomes in depression.
• High-frequency rTMS appears to induce broader, more widespread electrophysiological changes in the brain.