Table 5.
Stimulation paramterers and findings of randomized-controlled trials applying high-frequency TMS using a figure-of-eight coil.
| Study | Stimulation parameters | Risk of bias | Results | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Number of sessions | Target region | Location of coil | Frequency of stimulation | Duration | Intensity of stimulation | Method of control | |||
| Studies involving patients with AD | |||||||||
| Cotelli et al. (2006) | 1 session | LDLPFC and RDLPFC | SofTaxic Evolution navigator (x = ±35, y = 24, and z = 48) | 20 Hz | 600 ms from the onset of the visual stimulus, using a train of 10 pulses, 70 stimuli | 90% of RMT | Vertex stimulation with a coil held perpendicularly | High | Improvement of action naming speed during the stimulation of LDLPFC and RDLPFC |
| Cotelli et al. (2008) | 1 session | LDLPFC and RDLPFC | SofTaxic Evolution navigator (x = ±35, y = 24, and z = 48) | 20 Hz | 500 ms from the onset of the visual stimulus, using a train of 10 pulses, 70 stimuli | 90% of RMT | Vertex stimulation with a coil held perpendicularly | High | Improved action naming performance in the mild AD group and improved picture naming in the severe AD group after active stimulation |
| Eliasova et al. (2014) | 1 session | Right IFG | n.a. | 10 Hz | 2,250 pulses | 90% of RMT | Vertex stimulation | High | Enhancement of attention and psychomotor speed after right IFG stimulation after active stimulation |
| Ahmed et al. (2012) | 5 sessions | Bilateral DLPFC | 5 cm rostral in the same sagittal plane as optimal site for MT production | 20 Hz | 2,000 pulses/session | 100% of RMT | Coil elevated from the scalp | Some concerns | Improvement in global cognitive performance and daily activity in HF-rTMS group compared to LF and sham groups |
| Cotelli et al. (2011) | 10 session for 2 weeks or 20 sessions or 4 weeks | LDLPFC | SofTaxic Evolution Navigationsystem (frameless stereotaxic neuronavigation, Talairach x = −35, y = 24, z = 48) | 20 Hz | 2,000 pulses/session | 100% of RMT | Sham coil | High | Improvement in the active group in auditory sentence comprehension compared to baseline or placebo (even after 8 weeks) |
| Koch et al. (2018) | 10 sessions | PC | Softaxic Neuronavigation System | 20 Hz | 1,600 pulses/session | 100% of RMT | Sham coil | Some concerns | Improvement in active group in episodic memory, but not in global cognition and executive function |
| Rutherford et al. (2015) | Stage 1: 13 sessions (2 weeks active, 2 weeks sham) Stage 2: 10 sessions every 3 months | Bilateral DLPFC | using fix anatomical positions | 20 Hz | 2,000 pulses/session | 90–100% of RMT | 2-cm wooden block between the scalp and the real coil | Some concerns | Improvement in global cognitive performance in the active group compared to sham, especially during the early stage of the treatment |
| Wu et al. (2015) | 20 sessions | LDLPFC | n.a. | 20 Hz | 1,200 pulses/session | 80% of RMT | Tilted coil (180°) | Low | Improvement of behavioral and global cognitive symptoms |
| Studies involving patients with MCI | |||||||||
| Drumond Marra et al. (2015) | 10 sessions | LDLPFC | 5 cm in a parasagittal plane parallel to the point of maximum rMT | 10 Hz | 2,000 pulses/session | 110% of RMT | Sham coil | Low | Selective improvement in everyday memory compared to sham group |
| Padala et al. (2018) | 10 sessions/condition | LDLPFC | n.a. | 10 Hz | 3,000 pulses/session | 120% of RMT | Sham coil | Low | Improvement in apathy symptoms, global cognition, processing speed and clinical improvement compared to sham condition |
| Zhao et al. (2017) | 30 sessions | Parietal cortexposterior temporal cortex | According to the 10-20 EEG system: Parietal P3/P4 and posterior temporal T5/T6 | 20 Hz | 10 min/session, 10 s of 20 Hz/train, 20 s intermediate/train, i.e., 4,000 pulses/session | n.a. | Recorded sounds to mimic impulses | High | Improvement in global cognitive performance in the active group, especially in mild AD regarding memory and language |
AD, Alzheimer's disease; MCI, mild cognitive impairment; LDLPFC, left dorsolateral prefrontal cortex; RDLPFC, right dorsolateral prefrontal cortex; IFG, inferior frontal gyrus; RMT, resting motor threshold; EEG, electroencephalography.