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

Placing the anode on the left dorsolateral prefrontal in treating patients with first-episode major depressive
cortex (DLPFC) is the most common electrode placement disorder (MDD) in the frontal and temporal regions,
for tDCS. The cathode is typically located in the showing good safety and acceptability. Furthermore,
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contralateral cortex or the right superior orbital area. 57-59 a recent meta-analysis that analyzed four double-blind
Clinical studies have demonstrated the efficacy of anodal randomized controlled trials and five active treatment
tDCS targeting the DLPFC in alleviating depressive groups revealed that tACS was significantly effective and
symptoms and enhancing cognition, 35,57,60 which is also safe in alleviating depressive symptoms among patients
corroborated among older patients with depression. 58,59 with severe depression. However, the antidepressant
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Although tDCS does not yet surpass pharmacological effects of lower current levels or frequencies remain
treatments in effectiveness, it offers benefits for patients unclear. Although tACS has gained widespread attention
with treatment-resistant depression. 61,62 Nevertheless, for its potential in treating depression, research targeting
given its favorable tolerability, safety profile, ease of late-life depression remains limited. Furthermore, direct
administration, and minimal cognitive side effects, tDCS comparison studies on the therapeutic effects of tDCS and
undeniably emerges as an appealing option for managing tACS for depressive symptoms. To address this gap, more
geriatric depression. 63 studies are needed to provide crucial scientific evidence
To promote the therapeutic effects of tDCS on for improving the treatment of depressive symptoms
depression, various stimulation parameters and treatment and protecting the cognitive and emotional functions of
durations have been explored. A study indicated that individuals with depression.
combining tDCS with relevant cognitive activities can In 2017, Grossman et al. introduced a novel non-
enhance its antidepressant effects, suggesting that cognitive invasive brain stimulation technique by employing
activation in the target brain region during tDCS may “temporally interfering” (TI) stimulation as an innovative
amplify therapeutic outcomes. A meta-analysis revealed form of tACS. TI electrical stimulation, a promising
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that extending the tDCS duration significantly improves approach for treating neuropsychiatric disorders, can
its efficacy in treating depression. Furthermore, a review non-invasively target deep brain regions with spatial
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proposed that older patients with depression may benefit specificity by stimulating deep-seated pathological areas.
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more from higher current intensity (2 mA) and longer Despite its potential, the research on TI stimulation
treatment courses (30 sessions over 6 weeks). Moreover, remains in its nascent stages, and numerous challenges
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tDCS enhances cognitive functions such as episodic must be overcome before it can become a clinically viable
memory and language learning abilities, possibly achieved therapeutic modality.
through anodal tDCS activating cortical excitability and Researchers have come to realize that a fixed stimulus
modulating neuroplasticity. 65-67 These findings further parameter model applicable to all individuals is no
highlight the substantial potential of tDCS in the treatment longer suitable for cross-individual treatment because
of geriatric depression and the preservation of cognitive this approach ignores the unique differences between
function among older patients.
individuals, often leading to instability in treatment
Furthermore, tDCS is highly portable, making it effects. Consequently, more studies are shifting to
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suitable for home use. Cappon et al. conducted remote personalized therapy. Personalized stimulation strategies
monitoring of older patients with severe depression are designed to enhance therapeutic efficacy and optimize
undergoing home-based tDCS, demonstrating its safety treatment outcomes by tailoring protocols, parameters,
and feasibility. This study presents evidence supporting and goals to key patient characteristics (e.g., demographic
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the use of tDCS in a home setting, indicating the potential factors, brain anatomy, symptom characteristics, symptom
of tDCS as a significant tool in treating geriatric depression severity, and disease duration). 74-76 In neuromodulation,
in the future. personalized stimulation is mainly achieved by precisely
adjusting the electrode position, stimulation target, and
2.2.2. Transcranial alternating current stimulation (tACS) stimulation parameters (e.g., pulse frequency and even
tACS is a non-invasive neuromodulation technique waveform shape). At present, only variants of the non-
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that influences cortical excitability and autonomic invasive tACS approach have been tested on humans. By
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neural activity through the application of alternating applying high-definition tACS (i.e., a form of tACS that
electrical currents to the scalp. In some tACS sessions, provides more precise targeting of cortical structures) and
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the electrodes are placed on the frontal region and personalizing the frequency, The working memory capacity
bilateral mastoid regions. A randomized controlled trial of older adults can be improved. Further development of
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demonstrated the feasibility and good tolerability of using personalized tACS will provide more precise and effective
tACS at a frequency of 77.5 Hz and intensity of 15 mA treatment options for older patients with depression.
Volume 3 Issue 3 (2025) 4 doi: 10.36922/jcbp.5019