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CC BY 4.0 · J Neuroanaesth Crit Care
DOI: 10.1055/s-0045-1811591
Original Article

The Impact of General Anesthesia on Postoperative Cognitive Dysfunction Using Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment–Indonesian Version (MOCA-Ina) in Geriatric Patients

Farhana Mardila
1   Department of Anesthesiology & Intensive Care, Faculty of Medicine, Universitas Sumatera Utara
,
Rr Sinta Irina
1   Department of Anesthesiology & Intensive Care, Faculty of Medicine, Universitas Sumatera Utara
2   Department Anesthesiology & Intensive Care, Adam Malik Hospital
,
Dadik W. Wijaya
1   Department of Anesthesiology & Intensive Care, Faculty of Medicine, Universitas Sumatera Utara
2   Department Anesthesiology & Intensive Care, Adam Malik Hospital
,
Yuki Yunanda
3   Community Medicine Department, Faculty of Medicine, Universitas Sumatera Utara, Medan, Indonesia
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Abstract

Introduction

Postoperative cognitive dysfunction (POCD) is a serious issue in geriatric patients undergoing general anesthesia procedures. Perioperative cognitive function assessment is vital for selecting anesthesia techniques in elderly patients.

Methods

This pretest–posttest cohort study assessed the effect of general anesthesia on POCD in geriatric patients ≥60 years from three government hospitals in Medan. Cognitive function was measured using the Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment Indonesian version (MoCA-Ina) tests 1 day before and 3 days after surgery.

Results

Thirty-six patients were included, with an average age of 65.42 ± 4.23 years. The majority were female (52.8%), with a high school education (50%), and worked as farmers/laborers (25%). The average surgery duration was 150 ± 39.93 minutes. A significant decrease in MMSE (26.83 ± 1.5 vs. 26.58 ± 1.44) and MoCA-Ina (27.28 ± 1.06 vs. 27.05 ± 1.01) scores was observed 3 days postoperatively (p < 0.05), with high correlation between the two tests (97.2%; p > 1.00).

Conclusion

General anesthesia significantly affects POCD in geriatric patients based on MMSE and MoCA-Ina scores.


 

Keywords

general anesthesia - geriatric - MMSE - MoCA - POCD

Introduction

Postoperative cognitive dysfunction (POCD) is an underdiagnosed, common postoperative complication of surgery under general anesthesia (GA) in older patients.[1] POCD is a decrease in postoperative memory, attention, executive function, and processing speed that develop early in the postoperative period or persists for weeks to months. The population is aging globally, particularly in the developing world, and surgical operations in this population continue to rise.[2] [3] Studies show that older patients are more prone to POCD due to the changes in neurophysiology with aging and increased sensitivity to anesthetic drugs.[4]

Prevalence of POCD has been described to be variable with the timing of evaluation and the cognitive tests used. It has been described as early as within the first week after surgery and for months. The International Study of Postoperative Cognitive Dysfunction (ISPOCD) reported an incidence of 25.8% at 1 week and 10% at 3 months after surgery in patients older than 60 years.[5] Other studies have followed POCD up to 1 year. However, in clinical settings, short hospital stays limit long-term follow-up, and early identification of POCD remains crucial to guide postoperative care. Therefore, this study focused on cognitive changes detectable within 3 days postoperatively, a time frame that reflects routine hospital discharge planning and allows early detection of functional impairment.

Previous studies have indicated a significant association between GA and early postoperative cognitive decline, particularly in geriatric patients.[6] [7] [8] [9] Several anesthetic agents and techniques have been implicated in neuroinflammation, impaired cerebral perfusion, and altered neurotransmission, all of which contribute to the pathophysiology of POCD.[6] [7] [8] Neurocognitive testing tools such as the Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment–Indonesian version (MoCA-Ina) have been validated for POCD assessment. While MMSE is more specific for major cognitive decline, MoCA-Ina is more sensitive to detecting mild cognitive impairment.[10] [11] Several studies have used MMSE and MoCA individually and in combination to assess postoperative cognitive changes in the elderly.[9] [10] [11] However, no studies to date have evaluated both MMSE and MoCA-Ina together in a perioperative context for GA among the elderly population in Medan, Indonesia. This study aims to assess whether GA is associated with early POCD, using both cognitive assessment tools in a local clinical context.


 

Methods

This was a prospective pretest–posttest cohort study conducted in March 2025 at three government hospitals in Medan, Indonesia. The study was approved and registered by the Ethics Committee of Universitas Sumatera Utara (No. 104/KEPK/USU/2025).

Participants

Patients aged ≥60 years undergoing elective surgery under GA were enrolled. All participants provided written informed consent prior to participation.


 

Inclusion Criteria

  • Age ≥60 years.

  • ASA physical status I–III.

  • Undergoing elective noncardiac surgery under GA.

  • Able to communicate verbally and complete cognitive tests independently.


 

Exclusion Criteria

  • History of dementia or cognitive impairment.

  • History of psychiatric or neurological disorders.

  • Sensory impairments that could interfere with testing (e.g., severe vision/hearing loss).

  • Emergent surgery or ICU admission postoperatively.

  • Incomplete pre- or postoperative cognitive testing.

Patients were excluded if their preoperative MMSE or MoCA-Ina scores were below the standard cognitive thresholds (MMSE < 24, MoCA-Ina < 26), indicating baseline impairment.


 

Sample Size Calculation

Sample size was calculated using an effect size of 0.5 (moderate), power of 80%, and significance level of 0.05 for paired samples. The estimated minimum sample was 32 subjects. To compensate for potential dropouts, 36 patients were enrolled.


 

Cognitive Assessment

The MMSE and MoCA-Ina were used to evaluate cognitive function. Assessments were performed 1 day before surgery and on postoperative day 3 (POD3) by trained anesthesia residents under supervision. All assessors received prior training in the standardized administration of both tools.[10] [11]


 

Anesthesia Protocol

All patients received balanced GA using inhalational agents. Induction was performed with midazolam, fentanyl, propofol, and a neuromuscular blocker (e.g., rocuronium or atracurium). Anesthesia was maintained with sevoflurane in a 50% oxygen/air mixture, with additional analgesia using opioids (e.g., fentanyl). No total intravenous anesthesia or regional blocks were used. No intraoperative depth-of-anesthesia monitoring (e.g., Bispectral Index or processed electroencephalography [EEG]) was applied.


 

Frailty Assessment

Frailty scoring was not formally assessed, but ASA classification and baseline clinical data (age, comorbidities) were used as surrogate markers of physiological reserve.


 

Statistical Analysis

Data were analyzed using SPSS version 26 (IBM). Cognitive scores before and after surgery were compared using paired t-tests. Categorical variables were presented as frequencies and percentages, while continuous variables were expressed as means ± SD. A p <0.05 was considered statistically significant.


 

 

Results

A total of 36 geriatric patients were enrolled. The mean age was 65.42 ± 4.23 years, and 52.8% were female. Half of the participants had completed secondary education, and the most common occupations were farmers, laborers, or drivers (25%). The majority were ASA class III (58.3%) and underwent digestive surgery (44.4%), with a mean operative duration of 150 ± 39.93 minutes ([Table 1]).

Table 1

Patient demographics and baseline characteristics

Characteristic

Value

Total patients

36

Age (mean ± SD)

65.42 ± 4.23 years

Gender

 Male

17 (47.2%)

 Female

19 (52.8%)

Education level

 Low

13 (36.1%)

 Medium

18 (50.0%)

 High

5 (13.9%)

Occupation

 Civil servant

7 (19.4%)

 Private sector

4 (11.1%)

 Teacher/Lecturer

2 (5.6%)

 Military personnel

2 (5.6%)

 Farmer/Laborer/Driver

9 (25.0%)

 Housewife

8 (22.2%)

 Entrepreneur

3 (8.3%)

 Others

1 (2.8%)

ASA classification

 II

15 (41.7%)

 III

21 (58.3%)

Type of surgery

 Digestive

16 (44.4%)

 Urogenital

1 (2.8%)

 Gynecological

1 (2.8%)

 Skin and soft tissue

3 (8.3%)

 ENT

4 (11.1%)

 Orthopedic

5 (13.9%)

 Oncologic

5 (13.9%)

 Plastic

1 (2.8%)

Surgery duration (mean ± SD)

150 ± 39.93 min

Abbreviation: ASA, American Society of Anesthesiologists.


Education level: low = primary or less, medium = secondary school, high = college/university.


Cognitive Score Changes

There was a statistically significant decline in both MMSE and MoCA-Ina scores on postoperative day 3 compared with preoperative assessments:

  • MMSE: 26.83 ± 1.5 → 26.58 ± 1.44 (mean decline = 0.25 points; p = 0.008).

  • MoCA-Ina: 27.28 ± 1.06 → 27.05 ± 1.01 (mean decline = 0.23 points; p = 0.007).

Although both scores remained above standard cutoff values (MMSE ≥ 24; MoCA-Ina ≥ 26), a subset of patients exhibited clinically meaningful declines ([Table 2]).

Table 2

Comparison of pre- and postoperative MMSE and MoCA-Ina scores

Cognitive test

Preoperative score (T0)

Postoperative score (T1)

p-Value

MMSE

26.83 ± 1.5

26.58 ± 1.44

0.008

MoCA-Ina

27.28 ± 1.06

27.05 ± 1.01

0.007

Abbreviations: MMSE, Mini-Mental State Examination; MoCA-Ina, Montreal Cognitive Assessment Indonesian version; POCD, postoperative cognitive dysfunction; T0, 1 day before surgery; T1, 3 days after surgery.



 

POCD Incidence

  • Based on MMSE (<24): 2 patients (5.6%) developed POCD.

  • Based on MoCA-Ina (<26): 3 patients (8.3%) met the threshold for POCD.

One patient was classified as POCD-positive on both tests, while others differed ([Table 3]).

Table 3

Incidence of POCD based on MMSE and MoCA-Ina

Interpretation

MMSE (T0)

MMSE (T1)

MoCA-Ina (T0)

MoCA-Ina (T1)

Normal cognitive function

36 (100%)

34 (94.4%)

36 (100%)

33 (91.7%)

Mild POCD

0 (0%)

2 (5.6%)

0 (0%)

3 (8.3%)

Total

36 (100%)

36 (100%)

36 (100%)

36 (100%)

Abbreviations: MMSE, Mini-Mental State Examination; MoCA-Ina, Montreal Cognitive Assessment Indonesian version; POCD, postoperative cognitive dysfunction; T0, 1 day before surgery; T1, 3 days after surgery.


Note: Mild POCD was defined as MMSE < 24 or MoCA-Ina < 26.



 

Correlation between MMSE and MoCA-Ina

A strong correlation was observed between MMSE and MoCA-Ina scores on POD3 (Pearson's r = 0.82, p < 0.001). Cross-tabulation showed a concordance rate of 97.2% in detecting cognitive status changes ([Table 4]).

Table 4

Correlation between MMSE and MoCA-Ina

MMSE: normal

MMSE: POCD

Total

MoCA-Ina: normal

33 (91.7%)

0 (0.0%)

33 (91.7%)

MoCA-Ina: POCD

1 (2.8%)

2 (5.6%)

3 (8.3%)

Total

34 (94. 4%)

2 (5.6%)

36 (100%)

Abbreviations: MMSE, Mini-Mental State Examination; MoCA-Ina, Montreal Cognitive Assessment Indonesian version; POCD, postoperative cognitive dysfunction.


Note: p = 1.000 (McNemar test); agreement = 97.2%.



 

Subgroup Analysis

POCD cases (by either scale) were more common in patients aged >65 years and ASA III. There was no significant association between POCD incidence and gender, education level, or type of surgery. No formal frailty score was assessed.


 

 

Discussion

This study evaluated the incidence of POCD in elderly patients undergoing surgery under GA, using both the MMSE and the MoCA-Ina. We observed a statistically significant decline in both cognitive scores on POD3, with POCD incidence rates of 5.6% and 8.3% based on MMSE and MoCA-Ina, respectively.

Although the mean postoperative scores remained above the clinical thresholds (MMSE ≥ 24, MoCA-Ina ≥ 26), a small number of participants met the criteria for POCD, indicating that early cognitive changes can still occur in functionally independent elderly patients. Similar findings were reported in several studies that demonstrated POCD can manifest as early as 1 to 3 days after GA, particularly in older patients.[4] [12] Shi et al. observed a significant decline in MMSE scores within 3 days postoperatively,[4] while Naghibi et al. reported a higher incidence of POCD in GA compared with local anesthesia.[12]

MoCA-Ina detected more POCD cases than MMSE in our study. This is consistent with previous evidence showing that MoCA is more sensitive in detecting mild cognitive impairment, especially in executive function, abstraction, and visuospatial domains.[10] [11] Aytac et al. reported a POCD incidence of 32.9% using MoCA versus 15.2% using MMSE, suggesting MoCA's superior ability to capture subtle cognitive changes.[10] The correlation coefficient in our study (r = 0.82) closely mirrors those found by Jia et al. and others (r = 0.76–0.84), confirming the strong relationship between these two instruments.[11]

The pathophysiology of POCD is believed to involve a complex interplay of neuroinflammation, microglial activation, oxidative stress, and neurotransmitter disruption.[6] [7] Surgical trauma and exposure to anesthetic agents can contribute to blood–brain barrier dysfunction and increased cytokine release (e.g., IL-1β, TNF-α), which may impair neuronal signaling and cognitive processing.[6] [7] Animal studies have shown that inhalational agents such as isoflurane and sevoflurane may enhance β-amyloid aggregation and suppress BDNF signaling, leading to neurotoxicity.[7] [8] Recent studies have also indicated a role for the gut–brain axis and microbiota in modulating cognitive outcomes following surgery, further complicating POCD mechanisms.[13] However, these mechanisms were not directly assessed in our clinical study.

Our findings support the body of literature demonstrating that GA can induce short-term cognitive changes in older adults, even during moderately invasive surgeries of 2 to 3 hours of duration.[4] [7] [12] Most of our patients underwent gastrointestinal procedures, and the mean operative time was 150 minutes. Though not classified as high-risk, these procedures were still associated with measurable cognitive decline on POD3. The type and duration of surgery, as well as intraoperative anesthetic management, have been shown to significantly influence POCD incidence in other studies.[14] [15] Previous research suggests that certain anesthetic techniques, including the choice between inhalational and intravenous agents, may influence POCD risk.[14]

Additionally, the majority of our sample were ASA III, which may reflect a greater degree of systemic illness. Several studies have validated the ASA physical status classification as a useful predictor of postoperative risk, including cognitive outcomes.[15] [16] Although we did not observe a direct association in this small sample, this factor may merit further investigation. Preexisting cognitive impairment is another known risk factor for POCD, especially in elderly populations.[17] In our study, we excluded patients with baseline cognitive deficits; however, subtle, undiagnosed impairments may still exist and contribute to vulnerability. Furthermore, long-term observational studies in stroke survivors have demonstrated that even mild postoperative insults may accelerate cognitive decline over time, underscoring the need for extended follow-up in future studies.[18]

Importantly, we observed a high concordance rate (97.2%) between MMSE and MoCA-Ina, with MoCA detecting one additional POCD case. This reinforces the utility of MoCA-Ina as a sensitive tool for early perioperative cognitive screening. Its broader domain coverage and lower ceiling effect make it particularly suitable for identifying mild deficits in the elderly.[9] [10] [11] [19]

This study had several limitations. The sample size was relatively small (n = 36), which limits generalizability and statistical power. Second, cognitive testing was conducted only once after surgery, on POD3. As a result, we could not evaluate delayed or persistent POCD, which may emerge days or weeks later.[5] [20] Third, no intraoperative EEG, neuroimaging, or standardized delirium screening was used to distinguish POCD from other acute cognitive syndromes.[20] [21] Finally, while we documented anesthetic technique, we did not assess intraoperative variables such as hemodynamics, blood loss, or inflammatory markers, all of which may influence POCD risk.


 

Conclusion

This study demonstrated that elderly patients undergoing surgery under GA experienced a statistically significant decline in cognitive scores on postoperative day 3, as measured by MMSE and MoCA-Ina. While most scores remained within normal limits, 5.6% of patients showed POCD based on MMSE and 8.3% based on MoCA-Ina. MoCA-Ina detected more cases and showed a strong correlation with MMSE, suggesting it may be more sensitive for early cognitive screening. These findings support the importance of early postoperative cognitive assessment in elderly surgical patients. Further studies with larger samples and longer follow-up are needed to evaluate the persistence and long-term impact of POCD.


 

 

Conflict of Interest

None declared.

Acknowledgments

The authors would like to express their sincere gratitude to the Department/Study Program of Anesthesiology and Intensive Therapy, Faculty of Medicine, Universitas Sumatera Utara, and Adam Malik General Hospital, Medan, Indonesia, for providing the necessary facilities and institutional support.


Address for correspondence

Rr Sinta Irina, MD
Department of Anesthesiology & Intensive Care, Faculty of Medicine, Universitas Sumatera Utara, Adam Malik General Hospital
Medan 20155
Indonesia   

Publication History

Article published online:
15 September 2025

© 2025. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution License, permitting unrestricted use, distribution, and reproduction so long as the original work is properly cited. (https://creativecommons.org/licenses/by/4.0/)

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