Effects of repetitive transcranial magnetic stimulation on electroencephalogram and memory function in patients with mild cognitive impairment

Abstract

BACKGROUND

Mild cognitive impairment (MCI) is a high-risk precursor to Alzheimer’s disease characterized by declining memory or other progressive cognitive functions without compromising daily living abilities.

AIM

To investigate the efficacy of repetitive transcranial magnetic stimulation (rTMS) in patients with MCI.

METHODS

This retrospective analysis involved 180 patients with MCI who were admitted to The First Hospital of Shanxi Medical University from January 2021 to June 2023. Participants were allocated into the research (n = 98, receiving rTMS) and control groups (n = 82, receiving sham stimulation). Memory tests, cognitive function assessments, event-related potential–P300 tests, and electroencephalogram (EEG) examinations were conducted pre-treatment and post-treatment. Further, memory quotient (MQ), cognitive function scores, and EEG grading results were compared, along with adverse reaction incidences.

RESULTS

Pre-treatment MQ scores, long-term and short-term memory, as well as immediate memory scores, demonstrated no notable differences between the groups. Post-treatment, the research group exhibited significant increases in MQ scores, long-term memory, and short-term memory compared to baseline (P < 0.05), with these improvements being statistically superior to those in the control group. However, immediate memory scores exhibited no significant change (P > 0.05). Further, the research group demonstrated statistically better post-treatment scores on the Revised Wechsler Memory Scale than the control group. Furthermore, post-treatment P300 latency and amplitude improved significantly in the research group, surpassing the control group. EEG grading in the research group improved, and the incidence of adverse reactions was significantly lower than in the control group.

CONCLUSION

Patients with MCI receiving rTMS therapy demonstrated improved memory and cognitive functions and EEG grading and exhibited high safety with fewer adverse reactions.

Key Words: Repetitive transcranial magnetic stimulation; Mild cognitive impairment patients; Electroencephalogram; Memory function; Cognitive function

Core Tip: Mild cognitive impairment falls short of meeting the diagnostic criteria for dementia and is generally considered a transitional phase between normal aging and dementia. Repetitive transcranial magnetic stimulation is currently considered an emerging treatment for early cognitive rehabilitation. This study will investigate the effectiveness and safety of the treatment from neuropsychological and neurophysiological perspectives using the memory quotient and the electroencephalogram as the subjects.

INTRODUCTION

Mild cognitive impairment (MCI) represents a syndrome characterized by a significant decline in cognitive abilities, manifesting as mild memory or specific cognitive dysfunction that exceeds the expected decline according to an individual’s age and educational attainment. However, MCI is generally considered a transitional phase between normal aging and dementia as it falls short of meeting the diagnostic criteria for dementia[1]. Memory impairment is a core feature of MCI, with patients potentially experiencing issues in memory, language, attention, reasoning, or other cognitive domains, distinguishing MCI from dementia[2]. Epidemiological studies reveal that annually, approximately 10%–15% of patients with MCI progress to Alzheimer’s disease (AD), compared with a conversion rate of only 1%–2% in healthy populations. The exact etiology remains unclear, whereas prevalent risk factors include advanced age, neurodegenerative conditions, vascular pathologies, and chronic smoking or alcohol consumption[3-5]. The prevalence of MCI in the elderly population stands at 5.3%. Approximately 50% of individuals with MCI will develop dementia, with conversion rates increasing with age and disease duration, if no intervention is administered within 3–4 years[6]. Consequently, effective cognitive impairment treatment at the early stage is of utmost importance. MCI represents the optimal window for intervention to prevent progression to dementia, as early detection and management may help slow or even prevent further cognitive decline. Dementia is set to burden families and society substantially as the aging of China’s population structure deepens. Thus, in-depth research on MCI exhibits significant clinical and social value for effectively delaying and preventing dementia.

Repetitive transcranial magnetic stimulation (rTMS) is currently recognized as a therapeutic approach for early cognitive dysfunction rehabilitation. Multiple domestic and international studies have revealed the positive impact of rTMS on improving the cognitive function of patients with dementia, primarily by exerting a remodeling effect on the cerebral cortex[7]. Research into cognitive function improvements in AD with high-frequency rTMS predominantly centers on prefrontal cortex stimulation[8]. This therapy has gained wider acceptance in the mental, neurological, and rehabilitation fields. Furthermore, the literature supports the feasibility of rTMS in treating patients with MCI[9,10]. With its non-invasiveness, ease of operation, and reliability, rTMS is widely applied in clinical settings, especially as an adjuvant treatment for epilepsy, mental disorders, spinal cord injuries, and cerebral infarctions[11-13]. However, research on rTMS application in patients with non-traumatic MCI remains limited. Hence, this study focuses on observing the efficacy of rTMS in patients with MCI.

MATERIALS AND METHODS

Research participants

This retrospective analysis involved 180 patients with MCI treated at The First Hospital of Shanxi Medical University from January 2021 to June 2023. Based on different treatment approaches, they were assigned to the research (n = 98) and control groups (n = 82).

Inclusion criteria: (1) MCI diagnosis based on Petersen’s diagnostic criteria for MCI included self-reported memory decline corroborated by family members or informants, preserved general cognitive function, normal overall activities of daily living; (2) Objective evidence of memory impairment, such as memory test performance of ≤ 1.5 SDs below age-matched and education-matched controls; (3) Age 50–70 years; (4) No prior pharmacotherapy for cognitive impairment; and (5) Complete clinical data.

Exclusion criteria: (1) History of epilepsy; (2) Neuroimaging-confirmed neurological disorders (e.g., cerebral hemorrhage, cerebral infarction, intracranial space-occupying lesions) causing memory impairment; (3) Severe depression, anxiety, or other pseudodementia conditions; (4) Contraindications to rTMS treatment; (5) Immunodeficiency, coagulation abnormalities, malignant tumors, or organic lesions; (6) Presence of cardiac pacemakers or intracranial metal implants; and (7) Incomplete clinical data.

Methods

A MagPro-R30 magnetic stimulator (Tonica, Denmark) was used in the rTMS treatment of the research group. First, the resting motor threshold (RMT) was identified. Patients were seated with surface electrodes placed on the abductor pollicis brevis muscle, whereas the reference electrode was positioned at the metacarpophalangeal joint of the thumb. The stimulation site targeted the contralateral cortical motor area corresponding to the thumb. The stimulation coil was repeatedly adjusted over the scalp until reproducible, clear-waveform motor-evoked potentials (MEPs) were obtained. The stimulation intensity was then gradually reduced while maintaining the coil position until MEPs were elicited in 3 out of 5 consecutive stimuli, which define the RMT. Bilateral prefrontal areas received high-frequency stimulation at 80% RMT intensity (10 Hz per session) during rTMS treatment. Patients underwent 40 high-frequency treatment sessions (30 minute/session), consisting of 50 pulses per train (50 trains total) at 30-second intervals. Treatments were administered once daily, five times a week. The control group received sham stimulation with an inactive coil that mimicked the same stimulation parameters without delivering effective magnetic pulses.

Observation indicators

Memory function: The Wechsler Memory Scale–Revised Chinese version (WMS–RC) was employed to measure changes in patients’ memory quotient (MQ). The WMS–RC includes three major test categories: (1) Long-term memory; (2) Short-term memory; and (3) Immediate memory tests. The long-term memory test covers personal experiences, temporal and spatial memory, and digit span sequencing tasks (forward sequencing 1–100, backward sequencing 100–1, and cumulative calculations). The short-term memory test includes picture recall, visual recognition, visual reproduction, associative learning, tactile tests, and comprehension memory. The immediate memory test involves forward and backward digit spans. In this study, the primary observation items include WMS–RC subtest scores for digital span sequencing, picture recall, visual recognition, visual reproduction, associative learning, comprehension memory, and immediate memory, as well as the overall MQ. The MQ reflects the participant’s overall memory level and is derived from WMS–RC measurements. It is calculated by summing up the raw scores from each WMS–RC subtest to obtain a total score. The total score is then adjusted with an age-specific weighting factor based on the participant’s age. Finally, the weighted total score is converted to the MQ using standardized reference tables.

Cognitive function: This was assessed using the Montreal Cognitive Assessment (MoCA) to evaluate overall cognitive performance. The MoCA assesses cognitive domains, consisting of visuospatial and executive function, naming, attention, language, abstraction, delayed recall, calculation, and orientation. The total score is 30 points, with higher scores indicating better cognitive function. The scoring criteria are > 26 points (indicating normal cognitive function), 18–26 points (MCI), 10–17 points (moderate cognitive impairment), and < 10 points (severe cognitive impairment). The cut-off scores for cognitive impairment are illiterate at ≤ 13 points; primary school education at ≤ 19 points; secondary school education and above at ≤ 24 points, respectively.

Event-related potential-P300 test: The P300 test was conducted using the Neuroscan 64-channel event-related potential (ERP) system (United States). A visual “oddball” paradigm was used to elicit P300 responses. The latency and amplitude of the P300 component in response to target stimuli were measured.

Electroencephalogram examination: Electroencephalogram (EEG) was performed with an EEG machine with scalp electrodes placed on the patient. Recordings were taken while the patient was awake and in a quiet state, using both monopolar and bipolar montages. A hyperventilation test was conducted for 25–30 minutes, and EEG results were categorized as normal, mildly abnormal, moderately abnormal, or severely abnormal. EEG grading criteria include (1) Grade I (normal): Dominant α rhythm; (2) Grade II (mildly abnormal): Predominant θ waves; (3) Grade III (moderately abnormal): Predominant δ and θ waves with occasional α waves; (4) Grade IV (severely abnormal): Diffuse δ waves with scattered δ waves in some leads, accompanied by electrical silence in other regions; and (5) Grade V (extremely abnormal): Almost no detectable brain electrical activity.

Adverse reactions: The incidence of adverse reactions, including mild dizziness, nausea and vomiting, and diarrhea, was documented.

Statistical analysis

Statistical Package for the Social Sciences version 25.0 was used for statistical data analyses. Measurement data were expressed as mean ± SD. Intergroup comparisons for normally distributed measurement data were conducted using the t-test. The non-parametric Mann–Whitney U rank-sum test was used instead in cases where the data did not follow a normal distribution. Enumeration data were expressed as percentages and intergroup comparisons were conducted using the χ² test. A P-value of < 0.05 indicated statistical significance.

RESULTS

General characteristics

The research group exhibited a male-to-female ratio of 49:49, with an age range of 50–70 years (64.17 years ± 4.33 years). The average body mass index (BMI) was 23.33 kg/m² ± 1.31 kg/m², and the average disease duration ranged from 1 year to 4 years (2.32 years ± 0.96 years). The duration of education varied from 6 years to 46 years (9.81 years ± 1.77 years). Among these participants, 37 participants were unmarried/divorced, whereas 61 participants were married. Comorbidities included 40 cases, 35 cases, and 37 cases of hypertension, diabetes, and hyperlipidemia, respectively. The control group indicated a male-to-female ratio of 46:36, with an age range of 52–69 years (63.57 years ± 3.59 years). The average BMI was 23.03 kg/m² ± 1.21 kg/m², with disease duration ranging from 1 years to 6 years (2.38 years ± 1.01 years). The educational attainment of patients in this group ranged from 7 years to 16 years, with an average of 9.93 years ± 1.49 years. Further, 32 patients were unmarried or divorced and 50 patients were married. Hypertension, diabetes, and hyperlipidemia accounted for 31 patients, 28 patients, and 35 patients, respectively. No significant inter-group differences were observed in general characteristics (P > 0.05) (Table 1).

Table 1 Comparison of general characteristics.

	Control group (n = 82)	Research group (n = 98)	t/χ² value	P value
Gender (male/female)	46/36	49/49	0.666	0.414
Age (years)	63.57 ± 3.59	64.17 ± 4.33	1.001	0.318
Body mass index (kg/m2)	23.03 ± 1.21	23.33 ± 1.31	1.583	0.115
Disease duration (years)	2.38 ± 1.01	2.32 ± 0.96	0.408	0.684
Duration of education (years)	9.93 ± 1.49	9.81 ± 1.77	0.486	0.627
Marital status			0.030	0.862
Married	50	61
Unmarried/divorced	32	37
Hypertension	31	40	0.170	0.681
Diabetes	28	35	0.0482	0.826
Hyperlipidemia	35	37	0.452	0.502

Measurement data were conducted using the t-test; counting data were conducted using χ² test.

Changes in MQ and memory scores

The control group demonstrated no marked differences in MQ scores or memory scores post-treatment compared with pre-treatment values (P > 0.05). In contrast, the research group exhibited significant improvements in MQ scores as well as long- and short-term memory scores post-treatment compared with pre-treatment values (P < 0.05), whereas no significant difference was observed in immediate memory scores (P > 0.05). The research group demonstrated statistically significant net increases in MQ scores, long-term memory scores, and short-term memory scores (P < 0.05), except for immediate memory, compared with the control group (Table 2).

Table 2 Changes in memory quotient and memory scores in both groups.

		Memory quotient	Long-term memory	Short-term memory	Immediate memory
Before treatment	Control group (n = 82)	75.41 ± 11.83	19.74 ± 6.92	26.95 ± 10.52	4.59 ± 1.78
	Research group (n = 98)	75.66 ± 10.01	19.51 ± 6.79	27.63 ± 8.32	4.60 ± 2.38
	t value	0.154	0.224	0.484	0.031
	P value	0.878	0.822	0.629	0.975
After treatment	Control group (n = 82)	75.51 ± 10.00	20.73 ± 6.13	28.27 ± 8.19	4.67 ± 2.09
	Research group (n = 98)	86.53 ± 9.34a	23.62 ± 5.52a	33.93 ± 9.06a	5.12 ± 1.85
	t value	7.633	3.326	4.359	1.596
	P value	< 0.0001	0.001	< 0.0001	0.112
Net increase	Control group (n = 82)	0.13 ± 11.96	0.99 ± 9.27	0.63 ± 9.25	0.09 ± 2.84
	Research group (n = 98)	10.87 ± 7.53	4.11 ± 8.03	5.09 ± 11.77	0.52 ± 2.68
	t value	7.324	2.419	2.786	1.043
	P value	< 0.0001	0.017	0.005	0.298

^aP < 0.05 vs research group before treatment using t-test.

Changes in WMS–RC subscale scores

The research group showed significant improvements in the following WMS–RC subscale scores compared to pre-treatment values: (1) Forward digit span (1–100); (2) Backward digit span (100–1); (3) Cumulative calculations; (4) Visual recognition; (5) Visual reproduction; (6) Associative learning; (7) Comprehension memory; and (8) Digit span, with all improvements being statistically significant (P < 0.05). In contrast, the control group demonstrated no significant changes in any of these subscale scores (P > 0.05). Further, all post-treatment subscale scores were statistically higher in the research group than in the control group (P < 0.05) (Table 3).

Table 3 Comparison of changes in Wechsler Memory Scale-Revised Chinese version subscale scores.

	Control group (n = 82)			Research group (n = 98)
	Before treatment	After treatment	Net increase	Before treatment	After treatment	Net increase
Forward digit span (1–100)	7.05 ± 1.02	7.13 ± 1.92	0.09 ± 2.18	7.20 ± 2.58	7.93 ± 2.35a,b	0.72 ± 3.30
Backward digit span (100–1)	5.22 ± 1.86	5.49 ± 1.73	0.27 ± 2.46	5.43 ± 2.13	6.55 ± 1.76a,b	1.12 ± 2.05b
Cumulative calculations	7.03 ± 1.65	7.38 ± 2.11	0.35 ± 2.62	7.09 ± 2.32	8.00 ± 1.75a,b	0.91 ± 2.67
Visual recognition	6.09 ± 1.74	6.50 ± 1.95	0.41 ± 2.41	6.14 ± 2.17	7.09 ± 2.10a,b	0.95 ± 3.04
Visual reproduction	3.65 ± 1.50	3.74 ± 2.00	0.10 ± 2.57	3.59 ± 1.64	4.54 ± 2.06a,b	0.95 ± 2.58b
Associative learning	4.35 ± 1.96	4.78 ± 1.85	0.43 ± 2.66	4.43 ± 1.98	5.42 ± 1.77a,b	1.00 ± 2.66
Comprehension memory	5.50 ± 1.23	5.46 ± 1.37	-0.04 ± 1.97	5.46 ± 1.66	6.18 ± 1.47a,b	0.72 ± 2.12b
Digit span	4.78 ± 1.75	4.91 ± 1.81	0.13 ± 2.25	5.01 ± 1.82	5.82 ± 1.95a,b	0.81 ± 2.52

^aP < 0.05 vs research group before treatment.

^bP < 0.05 vs control group, t-test were used for comparison.

MoCA scores

At baseline, no evident differences were found in MoCA scores between the two groups. Post-treatment, the research group demonstrated a significant increase in both MoCA scores compared to baseline values (P < 0.05), whereas the control group showed no significant changes (P > 0.05). Figure 1 illustrates detailed comparisons.

Figure 1 Comparison of Montreal cognitive assessment scores between the two groups. The t-test were used for comparison; control group: n = 82, received sham stimulation; research group: n = 98, underwent repetitive transcranial magnetic stimulation. ^cP < 0.001. MoCA: Montreal cognitive assessment.

ERP–P300 latency and amplitude

At baseline, no significant differences in P300 latency and amplitude were found between the groups (latency: t = 1.103, amplitude: t = 0.201, P > 0.05). Post-treatment, the research group demonstrated a significant decrease in P300 latency and an evident increase in amplitude compared to baseline measurements (t = 13.267, t = 13.816, P < 0.0001). In contrast, the control group demonstrated no significant changes in either P300 latency or amplitude (t = 1.100, t = 1.101, P > 0.05). Moreover, the research group showed significantly shorter P300 latency and higher amplitude post-treatment compared with the control group (t = 12.831, t = 11.006, P < 0.0001) (Table 4).

Table 4 Comparison of event-related potential-P300 latency and amplitude between the two groups.

	Latency (ms)		t value	P value	Amplitude (uv)		t value	P value
	Before treatment	After treatment			Before treatment	After treatment
Control group (n = 82)	338.31 ± 18.79	341.34 ± 16.42	1.100	0.273	3.45 ± 0.99	3.63 ± 1.27	1.101	0.313
Research group (n = 98)	341.21 ± 16.47	312.18 ± 14.07	13.267	< 0.0001	3.48 ± 1.00	5.66 ± 1.20	13.816	< 0.0001
t value	1.103	12.831			0.201	11.006
P value	0.271	< 0.0001			0.841	< 0.0001

Measurement data were conducted using the t-test.

EEG improvement

At baseline, no noticeable differences were found in EEG grading between the two groups (χ² = 0.209, P = 0.901). Post-treatment, the research group demonstrated significant improvement in EEG grading compared with baseline (χ² = 6.242, P = 0.044). Mild abnormal EEGs (II) usually indicate a slight deviation in the form, frequency, amplitude, or distribution of brain waves. Normal people can demonstrate mild abnormal EEGs under emotional stress and poor rest conditions, and they generally do not have a significant impact on the patient’s health. Post-treatment, the results revealed that the research group’s EEG grading was significantly superior to that of the control group (χ² = 23.752, P < 0.0001) (Table 5).

Table 5 Comparison of electroencephalogram improvement.

		I	II	III	IV	V
Before treatment	Control group (n = 82)	13	57	12	0	0
	Research group (n = 98)	17	65	16	0	0
	χ² value	0.209
	P value	0.901
After treatment	Control group (n = 82)	15	37	30	0	0
	Research group (n = 98)	28	63	7	0	0
	χ² value	23.752
	P value	< 0.0001

Counting data were conducted using the χ² test.

Incidence of adverse reactions

Adverse reactions include diarrhea in 3 patients, nausea and vomiting in 6 patients, and mild dizziness in 7 patients of the control group, and diarrhea in 1 patient, nausea and vomiting in 4 patients, and mild dizziness in 5 patients of the research group. The total incidence of adverse reactions in the research group was 8.2%, which was significantly lower than the 19.5% observed in the control group (χ² = 4.976, P = 0.026) (Table 6).

Table 6 Comparison of adverse reactions, n (%).

	Diarrhea	Nausea and vomiting	Mild dizziness	Total incidence
Control group (n = 82)	3	6	7	16 (19.5)
Research group (n = 98)	1	4	3	8 (8.2)
χ² value				4.976
P value				0.026

Counting data were conducted using the χ² test.

DISCUSSION

MCI is a clinically prevalent condition, classified into two types based on the extent of cognitive impairment: (1) Non-amnestic MCI; and (2) Amnestic MCI. Non-amnestic MCI presents with a decline in cognitive functions other than memory and may progress to frontotemporal dementia, whereas amnestic MCI typically develops toward AD, with worsening symptoms significantly affecting daily life[14,15]. RTMS is a neurophysiological technique developed from transcranial magnetic stimulation. It generates a time-varying magnetic field that causes an electric field in the cerebral cortex, producing induced currents. These currents act on brain tissue, which stimulate neuronal depolarization and generate evoked potentials, thereby modulating the excitability of local cortical regions[16]. RTMS at different frequencies exerts varying effects on the cerebral cortex. In particular, high-frequency rTMS promotes the release of excitatory neurotransmitters, such as dopamine and glutamate, improves neural conduction velocity, and stimulates cortical excitability[17].

In this study, we initially investigated MQ alterations of the two patient groups post-treatment. The results revealed that the MQ score, along with long-term and short-term memory scores, in the research group increased after treatment compared to pre-treatment levels; however, no significant change was found in immediate memory. In contrast, the control group demonstrated no statistically significant differences in any of these parameters pre-treatment and post-treatment. The research group demonstrated significant improvements in scores for 1–100 forward digit span, 100–1 backward digit span, cumulative scores, visual recognition, visual reproduction, associative learning, comprehension memory, and digit span through the WMS-RC assessment. MCI is characterized by impaired short-term memory, with immediate memory remaining relatively intact. According to research, the most prominent and earliest-emerging cognitive impairments in patients with MCI and early AD are associated with explicit memory, such as associative learning, recall, and reproduction, with significant impairments found in experience and orientation abilities[18]. The short-term memory impairment in patients was notably alleviated after rTMS treatment, aligning with most clinical reports. Further, rTMS treatment caused improved MoCA scores, signifying enhancements in patients’ cognitive functions. Rektorova et al[19] revealed that rTMS stimulation of the left dorsolateral prefrontal cortex, a crucial brain region involved in cognitive processes, such as memory and executive function, could improve the executive function of patients with cerebrovascular disease. In recent years, several meta-analyses have investigated the effect of rTMS on elderly patients with cognitive impairment, indicating that rTMS may exert beneficial effects on cognitive function[20-22]. This study further revealed a significant decrease in P300 latency and a notable increase in amplitude after rTMS treatment compared to pre-treatment measurements. Further, both parameters in the treatment group were more favorable than those in the control group. Current evidence indicates that alterations in P300 latency and amplitude are closely associated with cognitive impairment severity. Specifically, more pronounced cognitive deficits correlate with prolonged P300 latency and reduced amplitude[23]. These results provide objective evidence supporting the efficacy of rTMS in improving cognitive function among patients with MCI. The observed improvements in MoCA scores, coupled with the decrease in P300 latency and increase in amplitude, collectively underscore the potential of rTMS to ameliorate cognitive dysfunction in individuals with MCI.

Extant research has established a correlation between the extent of EEG abnormalities and the degree of cognitive impairment[24]. EEG detects subtle declines in brain function before the manifestation of structural and metabolic abnormalities in patients with progressive MCI[25]. Resting-state EEG activity is characterized by an increase in low-frequency oscillations and a decrease in high-frequency oscillations in cognitively impaired individuals. Furthermore, EEG activity demonstrates a progressive decline during the transition from MCI to AD[26]. In the present study, a reduction in the proportion of patients demonstrating moderate EEG abnormalities was observed after rTMS treatment. This shift in EEG frequency patterns indicates an improvement in cerebral function, which may underlie the observed memory performance enhancement. RTMS treatment can restore the dynamic equilibrium between the cerebral hemispheres and reconstruct associated neural functions. It exerts modulatory effects on brain regions that are anatomically and functionally connected to the stimulation site, with transcallosal pathways facilitating effect on contralateral brain regions. Moreover, rTMS improves regulatory mechanisms governing neural balance, increases cognitive performance, and exerts neurotrophic effects through neurotransmitter release modulation and brain-derived neurotrophic factor expression upregulation. Further, it promotes cellular proliferation and differentiation, provides neuroprotective benefits, augments regional cerebral blood flow and metabolic activity, reconstructs cortical functional networks, and regulates various gene expressions and neurotransmitter levels. These mechanisms collectively improve cortical excitability in targeted brain regions, alleviate clinical symptoms, and enhance cognitive function[27,28]. RTMS treatment is distinguished by its high penetrative efficacy, which improves patient comfort and treatment adherence. It increases neuronal excitability and plasticity, restores regional cortical functionality, and directly stimulates the cerebral cortex, thereby mitigating cognitive impairment severity. During treatment, rTMS modulated self-awareness and regulated interhemispheric excitability, thereby achieving optimal therapeutic outcomes. Importantly, rTMS treatment was associated with a low incidence of adverse effects and demonstrates a favorable safety profile.

However, this study is subject to several limitations, including a relatively simplistic design, a limited sample size, and a short follow-up duration. The results indicate that rTMS improved therapeutic outcomes, alleviated clinical symptoms, and enhanced daily functioning in patients with MCI; however, the potential for bias in the study cannot be disregarded, which may be caused by limited sample size, limited observational indicators, etc. Thus, randomized controlled trials with larger cohorts and extended observation periods are warranted to identify optimal stimulation parameters and protocols, thereby maximizing the therapeutic efficacy of rTMS for cognitive impairment. Further, in clinical practice, we can use rTMS as an adjunctive physical stimulation therapy in the rehabilitation process, in addition to the patient’s medication for cyclic rTMS. Concurrently, rTMS-induced inter-epileptic seizures are the biggest side effect of rTMS, whether or not to induce inter-epileptic seizures is mainly associated with the stimulation intensity, frequency, stimulation site and other factors, the stimulation intensity of the stimulation of inter-epileptic seizures in the induction of the threshold strength of the stimulation above. Therefore, patients are recommended to be treated within the therapeutic parameters recommended by the rTMS safety guidelines.

CONCLUSION

In summary, rTMS represents a safe and effective non-pharmacological intervention for MCI and demonstrates the potential to mitigate memory decline, particularly as evidenced by EEG slowing, and to improve cognitive function to a measurable extent.