Page 11 - JCBP-3-3

Journal of Clinical and
Basic Psychosomatics Non-invasive neuromodulation for geriatric depression

2.2.3. Transcutaneous vagus nerve stimulation (tVNS) stimulation can affect neurotransmitter receptors; for

tVNS is a non-invasive alternative to traditional VNS. This instance, it may decrease 5-hydroxytryptamine 2C
technique directly stimulates vagal afferent fibers found receptors, increase 5-hydroxytryptamine 1A receptors,
in areas such as the auricle (outer ear) and neck, using and enhance N-methyl-D-aspartic acid receptors, thereby
these fibers to transmit electrical stimulation signals to the improving cognitive function and treating psychiatric
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solitary tract nucleus. Then, the solitary tract nucleus relays disorders.
the signal to critical brain regions such as the midbrain, The use of rTMS for treating depression has received
hypothalamus, amygdala, and hippocampus, effectively approval from the US Food and Drug Administration
alleviating depressive symptoms. 79,80 This technique (FDA). The FDA-approved standard rTMS protocol involves
aimed to mitigate depressive symptoms avoiding the risks delivering magnetic pulses at 10 Hz to the left DLPFC at
associated with invasive surgery. tVNS holds promise for 120% of the motor threshold, once daily, 5 times a week,
treating neurological and psychiatric disorders, including for 4 – 6 weeks, to achieve the therapeutic goal of treating
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depression, due to its favorable safety profile, cost- depression. Recent clinical studies have consistently
effectiveness, high tolerability, and minimal side effects. 81,82 shown that the DLPFC is the most common target area
At present, tVNS is available in two forms: transcutaneous for rTMS. Typically, the left dorsolateral prefrontal cortex
auricular VNS (taVNS) and transcutaneous cervical VNS. (LDLPFC) receives high-frequency stimulation, whereas
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A meta-analysis of four studies on taVNS indicates the right DLPFC receives low-frequency stimulation.
its superior efficacy in improving depressive symptoms In studies targeting older patients with depression, most
compared with sham stimulation. A recent review researchers tend to use high-frequency rTMS targeting the
83
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highlights the beneficial therapeutic effects of taVNS LDLPFC. However, when the effects of high-frequency
84
on reducing depressive symptoms. A study conducted stimulation of the LDLPFC and low-frequency stimulation
with 86 patients diagnosed with depression indicates of the right DLPFC on older patients were compared, the
that taVNS exhibits favorable clinical efficacy in cases of results showed no significant difference between the two
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mild-to-moderate severity. Although research on taVNS stimulation methods in improving depressive symptoms.
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in older populations is limited, Jacobs et al. found that in Intermittent theta-burst stimulation (iTBS) has emerged
a study of 30 healthy older adults, taVNS can effectively as an alternative to traditional rTMS, demonstrating similar
enhance associative memory, indicating its potential therapeutic responses and rates of depression symptom
value in improving cognitive function in older people, relief within shorter treatment periods. 98,99 Furthermore,
including those with late-life depression. Xu et al. suggest the combined use of rTMS and other therapeutic
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that taVNS may be an effective treatment for treatment- interventions, such as pharmacological treatments,
resistant depression in the elderly, although further has gained increasing attention. The combination of
research is needed to establish its long-term stability. 87 antidepressant medications with rTMS was found to yield
tVNS is recognized for its significant potential and superior outcomes compared with medication alone,
emerges as a promising treatment for both depression and significantly improving depressive symptoms, cognitive
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geriatric depression, thanks to its favorable safety profile, function, and overall quality of life.
cost-effectiveness, high tolerability, and minimal side The outcomes of using rTMS for treating older patients
effects. However, given the lack of substantial foundational with depression are heterogeneous. A study indicated
research and clinical evidence and the variability in that rTMS is significantly effective for older patients with
neural pathway activation based on stimulation locations, depression, with high acceptance rates and minimal side
different therapeutic outcomes may be achieved. 88,89 Thus, effects. A review incorporating several randomized
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further extensive clinical trials are warranted to optimize controlled trials and non-controlled studies found that
the efficacy and scope of this emerging therapeutic patients receiving rTMS had markedly better outcomes
technique. than the control group. Lu et al. suggested that rTMS
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enhances cortical excitability by stimulating damaged areas
2.3. rTMS in the frontal lobe, thereby improving cognitive function
rTMS is a non-invasive brain stimulation technique in older patients. Nevertheless, some studies suggest
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that induces electrical currents in specific regions of the that the effects of rTMS in older patients may be less
cerebral cortex through electromagnetic induction. 19,90 pronounced than that in younger individuals, possibly
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By modulating cortical excitability, high-frequency rTMS due to age-related frontal cortical atrophy and reduced
(up to 20 Hz) enhances cortical excitability, while low- neuroplasticity. 104,105 In recent years, the application of
frequency rTMS (≤1 Hz) tends to inhibit it. 91,92 Prolonged personalized rTMS in the treatment of depression has

Volume 3 Issue 3 (2025) 5 doi: 10.36922/jcbp.5019