Transcranial Magnetic Stimulation and Transcranial Direct Current Stimulation Across Mental Disorders: A Systematic...

Area of Science:

• Neuroscience
• Psychiatry
• Medical Engineering

Background:

• Noninvasive brain stimulation (NIBS) is effective for mental disorders, but optimal stimulation parameters remain unclear.
• Understanding dose-response relationships is crucial for maximizing NIBS efficacy.

Purpose of the Study:

• To determine specific NIBS dose parameters linked to the greatest symptom improvement across various mental disorders.
• To establish evidence-based guidelines for NIBS dosing in clinical practice.

Main Methods:

• Systematic review and dose-response meta-analysis of 110 randomized clinical trials (4820 participants) involving transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS).
• Data extracted on stimulation parameters and participant outcomes, analyzed using random-effects models.
• Searched PubMed, OVID, and Web of Knowledge databases up to April 30, 2023.

Main Results:

• Significant dose-response associations found for schizophrenia (negative symptoms, hallucinations), depression, treatment-resistant depression, and substance use disorder.
• Specific parameters, including high-frequency TMS on the left dorsolateral prefrontal cortex (LDLPFC) and tDCS on LDLPFC, showed bell-shaped dose-response curves.
• Low-frequency TMS on the right DLPFC and orbitofrontal cortex demonstrated plateaued or ascending dose-response curves for depression, treatment-resistant depression, obsessive-compulsive disorder, and PTSD.

Conclusions:

• NIBS efficacy is significantly influenced by specific dose parameters and targeted brain regions for different mental disorders.
• Findings suggest clinicians should carefully consider these dose parameters when prescribing NIBS.
• Further prospective, sham-controlled trials are recommended to validate these dose-response findings.