Evaluation of nonmemory cognitive parameters in psychiatric patients' pre- and post-electroconvulsive therapy: An observational study.

INTRODUCTION: Possibility of cognitive side effects has made electroconvulsive therapy (ECT) questionable. Variable deficits have been debated in memory cognition. Pattern of changes in nonmemory cognition pre- and post-ECT is not clear.
METHODOLOGY: Forty patients undergoing ECT were studied on nonmemory cognitive parameters before ECT, after a course of ECT, and after 4 weeks of last. ECT.
RESULTS: Nonmemory cognition improved during the course of ECT and over 4 weeks of ECT.
CONCLUSIONS: ECT does not affect the nonmemory cognition adversely.

Eectroconvulsive therapy (ECT) is a common and effective therapy for psychiatric disorders such as severe depression and acute psychosis. Its effects are quicker compared to other modes of therapy. However, there are doubts regarding its acceptability and safety profile. Cognitive impairment is the most debated side effect of ECT limiting its use.[1]

Cognitive impairments involve memory and other nonmemory aspects such as executive function, intelligence, reasoning, concentration, organizational skill deficit, loss of reasoning ability, and loss of intelligence.[2] Application of electrical current is densest in the medial temporal area; where lies structures which is significantly associated with memory formation.[3] However, ECT affects both temporal and frontal lobes, thus involvement of both memory and nonmemory neuropsychological functions is expected.[45]

Systematic review and meta-analyses[6] have revealed that there is no significant change in executive function from baseline to immediately following ECT; bilateral versus unilateral ECT or bifrontal versus bi-temporal ECT. One study has found greater acute executive dysfunction in brief pulse ECT than ultra-brief pulse ECT. There was no conclusive evidence of sub-acute effects of ECT. For medium-term effects, there was conclusive evidence suggesting no significant change from baseline. Rather, there have been studies suggesting that ECT induces a cascade of neurophysiological, neurochemical, and neurohistological changes resulting in synaptic strengthening, dendritic growth, branching, and new synapse formation. ECT has been opined as the most potent inducer of neuroplasticity.[789]

As there appears lot of ambiguity about the affection of nonmemory cognitive parameters in patients undergoing ECT, a study was undertaken to understand the true nature and pattern of nonmemory cognitive changes in patients requiring ECT before and after the procedure.

The objective was to evaluate the pattern of nonmemory cognitive deficits before and after ECT and to ascertain the role of various psychosocial illness and treatment-related parameters on cognitive functions.

METHODOLOGY

Forty consecutive psychiatric cases requiring ECT were included in the study. Informed consent was taken. Inclusion criteria were all psychiatric patients planned to undergo ECT, willing/fit to give consent, and without any medical/neurological comorbidity. Patients with a past history of psychiatric illness, coexisting medical/central nervous system illness, while on medication affecting cognition (other than psychotropic medication), and unwilling for the study were excluded. Sociodemographic pro forma was administered to assess the demographic, family, clinical, and social domains of participants. Diagnoses of psychiatric illnesses were made using International Classification of Diseases-10 criteria. In addition, Becks depression inventory (BDI)[101112] and Brief psychiatric rating scale (BPRS)[13] were used to measure the severity of depression and psychosis, respectively.

BDI is a widely used instrument for depression. It contains 21 questions, scored on a scale value of 0–3. Higher total scores indicate more severe depression. It has a high test–retest reliability (Pearson r = 0.93) and an internal consistency of α = 0.91.

BPRS is a 16-item rating scale to measure positive symptoms, general psychopathology, and affective symptoms. It is used commonly in psychotic disorders. Each symptom is rated 1–7. Higher the score, more severe is the disorder. Measures on BPRS are stable over time and have inter-rater reliability.

Trail making test was used to assess nonmemory cognition in processing speed and executive functioning. Trail making test has two parts: A and B. A is used primarily to examine cognitive processing speed. B, in which the subject alternates between numbers and letters, is used to examine executive functioning.[14]

Patients were evaluated clinically, started on psychopharmacological treatment, and decision to administer ECT was taken purely on clinical indications for the same. Common indications were suicidal ideation, catatonic features, lack of self-care, etc. As it was a clinical research, the choice of medication was made entirely on clinical requirement and psychiatrist preference. No attempt was made to standardize the same.

All subjects received twice weekly, modified, bi-temporal ECT by brief pulse machine. The entire anesthetic procedure was supervised by an anesthetist and ECT administration by a psychiatrist. Thiopentone, atropine, and succinyl choline were used during all ECT procedures in the recommended dosage. Seizure of adequate duration was produced under anesthesia and vital parameters were monitored till resumption of full consciousness.

Assessment of severity of illness and performance on trail-making test was done at baseline, after a course of ECT, and after 4 weeks of ECT. The resultant means and standard deviations (SDs) at the three points in time were compared statistically.

RESULTS

Mean age of the subjects was 34.62 years (SD - 3.68 years). Mean years of schooling was more than 12 years (median - 12 years). Mean duration of the symptoms was 22.62 days (SD - 6.05 days). About 81% of the subjects had diagnosis of depression and the rest were had nonaffective psychotic disorders. Mean seizure duration was 39.95 s (SD - 5.66 s). No patient of depressive illness had psychotic symptoms. Mean score on depression severity on BDI was 31.32 (SD - 2.33); which is severe. Score of psychosis on BPRS was also higher (90.71, SD - 2.81).

Scores on depression and psychosis improved statistically over the course of treatment [Table 1]. There was an improvement in both the trail-making tests over the course of treatment at all points in trail-making test A. In trail-making test B, though there was statistical improvement in score from the baseline to after a course of ECT, the same did not show any statistical change thereon [Table 2].

Table 1

Effects of electroconvulsive therapy on disease profile from baseline to four weeks of treatment

Table 2

Effects on electroconvulsive therapy on nonmemory cognition across from baseline to four weeks of electroconvulsive therapy

DISCUSSION

Our study showed that there was an improvement in nonmemory cognition. Processing speed and executive functioning improved over the course of treatment from before the ECT procedure to that of after the procedure. This change in nonmemory cognition could be attributed to various factors. This could be due to effects of ECT, effects of other prescribed drugs, due to improvement of illness which might have caused temporary cognitive impairment, or a natural course in the process of the mental illness.[215] A randomized study using a sham control while controlling the confounding factors would bring out those factors which are responsible for these changes in nonmemory cognition in a more specific manner.

The above finding negates the notion and clears the ambiguity that the ECT affects the nonmemory cognition in an adverse manner. Research findings also in this direction have been variable and inconclusive.[1516] Calev et al. argued that as ECT affects both frontal and temporal lobe, it is expected that the cognitive effects of the same would also encompass both memory and the nonmemory components.[15] Deficits in executive functions and other related nonmemory cognition have been found by the earlier researchers in this field.[3] However, no long-term controlled studies have been done to find out whether the nonmemory cognitive functions normalizes or not and if so when.[2]

Our findings do resonate the opinion of some of the researchers in the past.[789] Getz et al.[17] noted that the objective function of the individual improved after the ECT even though the individual persisted with subjective complaints of impairment. Fujita et al.[18] studied the effect of sine and pulse waveforms on the aspects of memory and nonmemory cognition on an average of 8.2 days after the last ECT. Attention and executive function statistically improved with pulse wave ECT.

CONCLUSIONS

Aspects of nonmemory cognitions such as processing speed and executive functions improved over the course of treatment from before ECT to after ECT.

Limitation of the study

This study being purely an observation one limits the specificity of finding. A control population without ECT or with sham ECT would have brought more clarity and is recommended. All patients were included in this study irrespective of the type of drugs they were on. However, as ECT is not the first line of treatment; it is not possible to have drug-naive population in clinical research. Clinical indication for ECT was as per the treating psychiatrist and there was no standardization done in this direction. An empirical study keeping the above limitations in mind will add further merit to the subject.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.