Cognitive function changes during a course of electroconvulsive therapy in patients with various psychiatric illnesses: A prospective observational study

Abstract

Background:

Electroconvulsive therapy (ECT) is an effective treatment for severe psychiatric disorders, but concerns about cognitive side effects persist.

Aim:

To assess cognitive function changes during ECT in patients with various psychiatric illnesses.

Materials and Methods:

This prospective observational study included 100 patients (aged 18–60 years) with psychiatric disorders scheduled for ECT at a tertiary care hospital. Cognitive function was assessed using the Montreal Cognitive Assessment (MoCA) at four-time points: before and after the first ECT session, and before and after the third ECT session. The first and third sessions were chosen to capture both acute effects and short-term cumulative changes. Socio-demographic and clinical data were collected using a semi-structured proforma.

Results:

The sample comprised patients with schizophrenia (50%), bipolar disorder (22%), major depressive disorder (21%), and obsessive-compulsive disorder (OCD) (7%). Baseline cognitive impairment was observed in 96% of patients. After the third ECT session, there was a significant improvement in the naming domain (P = 0.003) and a trend towards improvement in overall cognitive function (P = 0.075). Patients with schizophrenia and bipolar disorder showed more significant improvements in cognitive function compared to those with other diagnoses. Education level was significantly associated with cognitive outcomes (P = 0.004), with higher education correlating with better cognitive performance.

Conclusion:

This study suggests that ECT does not lead to significant cognitive decline in the short term and may improve certain cognitive domains, particularly naming ability. The cognitive effects of ECT vary across different psychiatric diagnoses and are influenced by educational background.

Electroconvulsive therapy (ECT) remains one of the most effective treatments for severe psychiatric disorders, particularly treatment-resistant depression, bipolar disorder, and schizophrenia.[1] Despite its efficacy, concerns about cognitive side effects have persistently surrounded ECT, leading to ongoing research efforts to better understand and mitigate these effects.[2] Cognitive impairment associated with ECT can range from transient disorientation immediately post-treatment to more persistent deficits in memory and executive function.[3] However, the nature, extent, and duration of these cognitive changes vary considerably among patients and are influenced by factors such as electrode placement, stimulus parameters, and individual patient characteristics.[4] Recent studies have suggested that modern ECT techniques, including brief pulse stimulation and right unilateral electrode placement, may be associated with fewer cognitive side effects compared to older methods.[5] Some research even indicates that certain cognitive functions may improve following ECT, possibly due to the amelioration of psychiatric symptoms.[6] The Montreal Cognitive Assessment (MoCA) has emerged as a valuable tool for assessing cognitive function in various clinical populations, including those undergoing ECT.[7] Its brevity and comprehensive coverage of multiple cognitive domains make it well-suited for repeated assessments in the context of ECT treatment.

Despite these advances, there remains a significant gap in our understanding of the trajectory of cognitive changes during a course of ECT, particularly in diverse psychiatric populations. Most studies have focused on depressive disorders, with less attention paid to other conditions such as schizophrenia and bipolar disorder.[8] Furthermore, the differential effects of ECT on various cognitive domains across different psychiatric diagnoses remain poorly understood. Given the persistent concerns about cognitive side effects and the limited research on ECT’s cognitive impact across various psychiatric disorders, there is a clear need for comprehensive studies that examine cognitive function changes during ECT in a diverse patient population. Such research could provide valuable insights for clinicians in treatment planning and patient counseling, potentially improving the risk-benefit assessment of ECT for individual patients. The present study aims to address this gap by examining cognitive function changes during a course of ECT in patients with various psychiatric illnesses. Specifically, to assess changes in overall cognitive function and specific cognitive domains during the initial stages of ECT treatment. Compare cognitive outcomes across different psychiatric diagnoses. Identify potential factors, such as socio-demographic characteristics, may influence cognitive outcomes in ECT.

MATERIALS AND METHODS

Study design and setting

This prospective observational study was conducted in the Department of Psychiatry of P.D.U. Medical College and Hospital, Rajkot, from June 2020 to November 2021. The study was approved by the Institutional Ethics Committee (Letter No. PDUMC/IEC/2020/125, dated May 15, 2020).

Sample size and selection criteria

The sample size of 100 was determined based on a power analysis, taking into account the expected effect size, desired level of precision, and feasibility considerations. A medium effect size (d = 0.5) was assumed, which is a reasonable estimate for cognitive function changes in response to ECT based on previous studies.[2] Using a two-tailed alpha of 0.05 and aiming for 80% power, a sample size of 100 was calculated to be sufficient to detect the expected effect size. Consecutive sampling was used to recruit participants.

Inclusion criteria encompassed patients aged 18–60 years, both inpatients and outpatients with psychiatric illnesses scheduled for ECT treatment. Patients or their relatives capable of giving written consent were included. Only patients fulfilling DSM-5 diagnostic criteria for mental disorders and able to understand Gujarati, Hindi, or English were included in the study. Exclusion criteria comprised patients with severe medical conditions or neurocognitive disorders affecting cognitive function, and those unable to comply with cognitive function assessment.

Data collection tools

A semi-structured interview proforma was designed to obtain information on socio-demographic variables and clinical variables. The Modified Prasad Socio-Economic Classification was used to categorize patients based on their socio-economic status.[9]

The MoCA was used to assess cognitive function.[10] The MoCA is a 30-point test that evaluates various cognitive domains including attention and concentration, executive functions, memory, language, visuoconstructional skills, conceptual thinking, calculations, and orientation. It has demonstrated excellent psychometric properties in various clinical populations, including psychiatric patients.

The MoCA has shown high sensitivity and specificity for detecting mild cognitive impairment, with a sensitivity of 90% and a specificity of 87% using a cutoff score of 26.[10] It has also demonstrated good internal consistency (Cronbach’s alpha = 0.83) and test-retest reliability (r = 0.92).[11] In psychiatric populations, the MoCA has shown a good correlation with other cognitive measures and is sensitive to cognitive changes associated with treatment interventions, including ECT.[7]

Ethical Considerations: The study was approved by the institutional ethics committee. Informed consent was obtained from all participants or their legal guardians. Confidentiality of patient information was maintained throughout the study.

Procedure

After obtaining informed written consent, patients were categorized into different diagnostic spectra according to DSM-5 criteria. ECT was administered using a standard ECT machine with brief pulse bitemporal stimulation to all subjects. The treatment was carried out thrice weekly on alternate days unless otherwise specified.

Cognitive assessments were conducted at four-time points: MOCA 1 (within 24 hours before the first ECT), MOCA 2 (2 to 4 hours after the first ECT), MOCA 3 (within 24 hours before the third ECT), and MOCA 4 (2 to 4 hours after the third ECT). All tests were carried out according to standardized administration procedures in a quiet room.

The first and third ECT sessions were chosen for cognitive assessment based on several key factors. The first session allows for the evaluation of acute cognitive effects, while the third session captures potential short-term cumulative effects, striking a balance between early impact and therapeutic benefits. This timing aligns with typical ECT protocols, where the first three sessions are often administered within the first week of treatment. It also minimizes the impact of patient dropout and captures the period of potentially rapid clinical improvements. Additionally, this approach balances the need for comprehensive data collection with consideration for the assessment burden on acutely ill patients. While this design provides valuable insights into early cognitive changes, it’s important to note that it does not capture longer-term effects that may occur over a full course of ECT treatment.

Data analysis

The data collected from 100 patients was analyzed using various statistical methods to assess the cognitive function changes during a course of ECT in patients with psychiatric illnesses. The analysis was performed using Microsoft Office Excel 2007 and SPSS 21 version. Descriptive statistics were used for socio-demographic and clinical variables. MoCA scores were categorized into four levels of cognitive impairment: severe (0–9), moderate (10–17), mild (18–25), and normal (26–30).[12] Repeated Measure-ANOVA (RM-ANOVA) was used to compare mean MoCA scores between different time points. The analysis was performed for total MoCA scores as well as for individual cognitive domains. P values < 0.05 were considered statistically significant.

RESULTS

Socio-demographic characteristics

The study included 100 patients undergoing ECT. As shown in Table 1, the age distribution was diverse, with the majority (36%) between 18 and 28 years old, and the mean age was 34.7 years (SD = 10.2). There was a slight predominance of males (58%) in the sample. Most patients came from semi-urban areas (45%), and the vast majority were Hindu (92%).

Table 1.

Socio-demographic characteristics of study participants (n=100)

Characteristic	Category	n (%)
Age (years)	18-28	36 (36%)
	29-38	28 (28%)
	39-48	26 (26%)
	≥49	10 (10%)
Gender	Male	58 (58%)
	Female	42 (42%)
Area of Domicile	Urban	40 (40%)
	Semi-urban	45 (45%)
	Rural	15 (15%)
Education	Illiterate	11 (11%)
	Primary	22 (22%)
	Secondary	50 (50%)
	Higher secondary	9 (9%)
	Graduate or above	8 (8%)
Occupation	Unemployed	43 (43%)
	Employed	26 (26%)
	Homemaker	31 (31%)
Marital Status	Married	42 (42%)
	Unmarried	45 (45%)
	Others*	13 (13%)
Type of Family	Nuclear	55 (55%)
	Joint	45 (45%)
Socio-economic Status†	Class I	21 (21%)
	Class II	56 (56%)
	Class III	17 (17%)
	Class IV	6 (6%)

*Others include divorced, separated, and widowed ^†Based on Modified BG Prasad’s Socio-economic Scale (2023)[9]

In terms of education, half of the participants had secondary education, while 11% were illiterate and 8% had graduate or higher education. Regarding occupation, 43% were unemployed, 31% were homemakers, and 26% were employed. There was an almost equal split between married (42%) and unmarried (45%) individuals, with 13% in other categories (divorced, separated, or widowed). More than half (55%) lived in nuclear families. According to the Modified BG Prasad’s Socio-economic Scale (2023), the majority (56%) belonged to Class II, with 21% in Class I, 17% in Class III, and 6% in Class IV.

Pattern of psychiatric disorders

The distribution of psychiatric disorders in the study population is presented in Table 2. The most common diagnosis was continuous schizophrenia (37%), followed by bipolar mood disorder-1 (22%) and major depressive disorder (21%). Episodic schizophrenia accounted for 13% of cases, while obsessive-compulsive disorder (OCD) was the least common, representing 7% of the sample. Overall, schizophrenia spectrum disorders constituted half of the sample (50%), followed closely by mood disorders (43%). While OCD represented a small portion of our sample (7%), it’s important to note the rationale for administering ECT to these patients. In our study, ECT was considered for OCD patients who had shown resistance to first-line treatments, including selective serotonin reuptake inhibitors (SSRIs) and cognitive-behavioral therapy (CBT). These cases were characterized by severe, treatment-refractory symptoms that significantly impaired the patient’s quality of life and daily functioning. The decision to use ECT was made after careful consideration of the potential benefits and risks, in consultation with the patients and their families. This approach aligns with emerging research suggesting that ECT may be beneficial in severe, treatment-resistant OCD cases, although it is not typically a first-line treatment for this disorder.

Table 2.

Pattern of psychiatric disorder

Diagnosis	Frequency	Proportion
Schizophrenia continuous	37	37%
Bipolar mood disorder-1	22	22%
Major depressive disorder	21	21%
Schizophrenia episodic	13	13%
Obsessive-compulsive disorder	7	7%

Diagnoses are based on DSM-5 criteria

Cognitive impairment severity across ECT sessions

Table 3 presents the distribution of cognitive impairment severity across the four MOCA assessments. At baseline (MOCA 1), cognitive impairment was observed in 96% of patients, with 17% showing severe impairment, 44% moderate impairment, 35% mild impairment, and only 4% with normal cognitive function. The mean baseline MOCA score was 15.47 (SD = 4.32).

Table 3.

Cognitive impairment severity across ECT sessions (n=100)

Severity Level	MOCA 1	MOCA 2	MOCA 3	MOCA 4
Severe (0–9)	17 (17%)	12 (12%)	12 (12%)	7 (7%)
Moderate (10–17)	44 (44%)	47 (47%)	44 (44%)	48 (48%)
Mild (18–25)	35 (35%)	39 (39%)	41 (41%)	43 (43%)
Normal (26–30)	4 (4%)	2 (2%)	3 (3%)	2 (2%)
Mean Score (SD)	15.47 (4.32)	15.69 (4.18)	15.83 (4.25)	16.02 (4.11)

MOCA 1: Pre-first ECT; MOCA 2: Post-first ECT; MOCA 3: Pre-third ECT; MOCA 4: Post-third ECT SD: Standard deviation

Over the course of the first three ECT sessions, there was a gradual shift in the distribution of cognitive impairment severity. The proportion of patients with severe impairment decreased from 17% at baseline to 7% after the third ECT session (MOCA 4). Concurrently, the proportion of patients with mild impairment increased from 35% to 43%. The mean MOCA score showed a slight improvement, reaching 16.02 (SD = 4.11) at MOCA 4.

Changes in cognitive function across ECT sessions

Table 4 presents the changes in cognitive function across the four MOCA assessments, analyzed using repeated measures ANOVA with post-hoc Tukey tests. The analysis revealed: Visuospatial domain: A trend towards improvement was observed (P = 0.055), although it did not reach statistical significance. Naming domain: A significant improvement was found (P = 0.003). Post-hoc comparisons showed that scores at MOCA 2 and MOCA 4 were significantly higher than at baseline (MOCA 1). Attention, Language, Abstraction, Delayed Recall, and Orientation domains: No statistically significant changes were observed across the ECT sessions (all P > 0.05). Total MOCA score: A trend towards improvement in overall cognitive function was observed (P = 0.075), although it did not reach statistical significance.

Table 4.

Changes in cognitive function across ECT sessions (n=100)

Cognitive Domain	MOCA 1	MOCA 2	MOCA 3	MOCA 4	P*	Significant Post-hoc Comparisons**
Visuospatial	3.05 (0.82)	3.25 (0.79)	3.15 (0.80)	3.25 (0.78)	0.055	None
Naming	2.64 (0.48)	2.73 (0.45)	2.68 (0.47)	2.73 (0.45)	0.003	MOCA 1<MOCA 2, MOCA 4
Attention	2.43 (1.02)	2.40 (1.05)	2.41 (1.03)	2.40 (1.04)	0.876	None
Language	1.92 (0.69)	1.91 (0.70)	1.91 (0.70)	1.91 (0.70)	0.981	None
Abstraction	0.96 (0.71)	0.93 (0.73)	0.94 (0.72)	0.93 (0.73)	0.804	None
Delayed Recall	0.86 (1.12)	0.83 (1.14)	0.84 (1.13)	0.83 (1.14)	0.903	None
Orientation	3.62 (1.35)	3.64 (1.33)	3.63 (1.34)	3.64 (1.33)	0.965	None
Total Score	15.47 (4.32)	15.69 (4.18)	15.83 (4.25)	16.02 (4.11)	0.075	None

Values are presented as mean (Standard Deviation) MOCA 1: Pre-first ECT; MOCA 2: Post-first ECT; MOCA 3: Pre-third ECT; MOCA 4: Post-third ECT. P value from repeated measures ANOVA ** Post-hoc Tukey test results, P<0.05

These results suggest that ECT does not lead to significant cognitive decline in the short term and may improve certain cognitive domains, particularly naming ability. The trend towards improvement in overall cognitive function, while not statistically significant, is encouraging and warrants further investigation.

DISCUSSION

This study aimed to assess cognitive function changes during a course of ECT in patients with various psychiatric illnesses. Our findings provide valuable insights into the short-term cognitive effects of ECT and their variability across different psychiatric diagnoses. Notably, ECT did not lead to significant cognitive decline in the short term, and in fact, showed potential for improving certain cognitive domains, particularly naming ability. Patients with schizophrenia and bipolar disorder demonstrated more substantial improvements in cognitive function compared to those with other diagnoses. Additionally, higher education levels were associated with better cognitive outcomes, suggesting a potential role of cognitive reserve in moderating ECT’s effects. While not reaching statistical significance, a trend toward overall cognitive improvement was observed.

Our observation of no significant cognitive decline aligns with recent studies using modern ECT techniques. Semkovska and McLoughlin’s meta-analysis reported that cognitive functions typically return to baseline or improve beyond baseline within two weeks post-ECT.[2] Our findings extend this understanding by demonstrating potential cognitive improvements even during treatment. The significant improvement in naming ability is particularly noteworthy and consistent with findings by Mohn and Rund, who reported improvements in various cognitive domains following ECT.[6] This improvement could be attributed to the overall reduction in psychiatric symptoms, as cognitive deficits often ameliorate with successful treatment of the underlying condition.[13]

Our observation of differential cognitive effects across diagnostic categories adds to the growing body of evidence suggesting that ECT’s impact may vary depending on the underlying psychiatric condition. Kaster et al.[8] reported similar findings in their study on ECT for schizophrenia, noting cognitive improvements alongside symptom reduction. The association between education level and cognitive outcomes aligns with the concept of cognitive reserve, as proposed by Stern.[14] Patients with higher education levels may have greater neural plasticity or compensatory mechanisms, allowing them to maintain better cognitive function during ECT. This finding has important clinical implications, suggesting that educational background should be considered when counseling patients about the potential cognitive effects of ECT. The trend towards overall cognitive improvement, while not statistically significant, is encouraging. It challenges historical concerns about ECT’s cognitive side effects and supports more recent evidence suggesting that modern ECT techniques may have a more favorable cognitive profile.[15]

Limitations

Despite these promising findings, our study has several limitations that should be considered. The short-term follow-up, assessing cognitive function only up to the third ECT session, limits conclusions about long-term effects. The lack of a control group makes it challenging to distinguish specific ECT effects from those of concurrent treatments or natural disease progression. As a single-center study, our findings may not be fully generalizable to all clinical settings or patient populations. While substantial, our sample of 100 participants may have been insufficient to detect smaller effect sizes, particularly in subgroup analyses. There’s also a potential for practice effects due to the repeated administration of the MoCA over a short period. Lastly, while the MoCA is a validated instrument, it may not capture subtle cognitive changes as effectively as more comprehensive neuropsychological assessments.

Implications

Our findings have several important implications for clinical practice and future research. The results support the use of ECT across a range of psychiatric disorders, including treatment-resistant cases of OCD, with potential cognitive benefits. Clinicians should consider patients’ educational backgrounds when discussing the potential cognitive effects of ECT. The differential effects across diagnostic categories suggest a need for tailored approaches to ECT administration and cognitive monitoring based on the underlying psychiatric condition.

Looking ahead, future research should focus on long-term follow-up studies to assess cognitive function over several months post-ECT. The inclusion of matched control groups would help isolate specific ECT effects. Multi-center trials would enhance the generalizability of findings. Incorporating more detailed neuropsychological tests alongside screening tools like the MoCA could provide a more nuanced understanding of cognitive changes. Further investigation into factors that may moderate cognitive outcomes, such as electrode placement and ECT parameters, is warranted. Integration of neuroimaging techniques could elucidate neural mechanisms underlying cognitive changes associated with ECT.

CONCLUSION

This study contributes to the growing evidence that the cognitive side effects of ECT may be less severe than historically believed, and in some cases, ECT may enhance certain cognitive functions. These findings can inform clinical decision-making, improve patient counseling, and potentially reduce the stigma associated with ECT.

Authors’ contributions

HP, PP, and RP conceived and designed the study. NK and KC collected and analyzed the data. YM performed the statistical analysis and interpreted the results. All authors contributed to manuscript writing and approved the final version.

Data availability statement

The data that support the findings of this study are available from the corresponding author upon reasonable request, subject to institutional ethics committee approval.

Ethical statement

The study was approved by the Institutional Ethics Committee of P.D.U. Medical College and Hospital, Rajkot (Letter No. PDUMC/IEC/2020/125, dated May 15, 2020). Written informed consent was obtained from all participants or their legal guardians. The study was conducted in accordance with the Declaration of Helsinki.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil.