Electroconvulsive therapy (ECT) serves as an effective adjuvant or alternative modality for major depressive disorder, schizophrenia, or bipolar affective disorder refractory to or contraindicated to psychopharmacological treatment. Anesthetics have been introduced into ECT sessions to alleviate ECT-inducing discomfort sensation, tachycardia, arrhythmia, hypertension, and anxiety. Propofol is highly lipid soluble and able to rapidly cross the blood-brain barrier (BBB), which leads to rapid onset of sedation and hypnosis. Meanwhile, propofol has hemodynamic depressant effect and attenuates hypertensive surge during ECT. Characteristics mentioned above make propofol one of widely used anesthetics for anesthetized ECT.

Propofol can be administered with bolus injection or target-controlled infusion (TCI). Compared with bolus injection, TCI provides relatively constant concentration at site of interest based on computer simulation with input of pharmacokinetic parameters, such as age, body weight, body height, etc. However, propofol is also well known for anticonvulsant property, which may inevitably interfere with seizure propagation by electroconvulsive stimulus and diminish consequent efficacy. Thus, dosage of electrical stimulus may be increased to achieve ideal seizure quality in this setting, which also leads to higher risk of subsequent cognitive impairment.

In our clinical practice, TCI system reduces total amount of propofol in comparison with bolus injection method. Therefore, we hypothesize that application of TCI system in anesthetized ECT relates to lower dosage of electrical stimulus and decreased incidence or severity of post-treatment cognitive impairment.

Electroconvulsive therapy (ECT) serves as an effective adjuvant or alternative modality for major depressive disorder, schizophrenia, or bipolar affective disorder refractory to or contraindicated to psychopharmacological treatment. Anesthetics have been introduced into ECT sessions to alleviate ECT-inducing discomfort sensation, tachycardia, arrhythmia, hypertension, and anxiety. Propofol is highly lipid soluble and able to rapidly cross the blood-brain barrier (BBB), which leads to rapid onset of sedation and hypnosis. Meanwhile, propofol has hemodynamic depressant effect and attenuates hypertensive surge during ECT. Characteristics mentioned above make propofol one of widely used anesthetics for anesthetized ECT.

Propofol can be administered with bolus injection or target-controlled infusion (TCI). Compared with bolus injection, TCI provides relatively constant concentration at site of interest based on computer simulation with input of pharmacokinetic parameters, such as age, body weight, body height, etc. However, propofol is also well known for anticonvulsant property, which may inevitably interfere with seizure propagation by electroconvulsive stimulus and diminish consequent efficacy. Thus, dosage of electrical stimulus may be increased to achieve ideal seizure quality in this setting, which also leads to higher risk of subsequent cognitive impairment.

In our clinical practice, TCI system reduces total amount of propofol in comparison with bolus injection method. Therefore, we hypothesize that application of TCI system in anesthetized ECT relates to lower dosage of electrical stimulus and decreased incidence or severity of post-treatment cognitive impairment.

Inclusion Criteria:

• Age between 20 years old and 65 years old
• Diagnosis of major depressive disorder, bipolar disorder, and schizophrenia, compatible with SCID for DSM-5, with clinical necessity of ECT under a psychiatrist's evaluation and decision
• Patients with adequate visual acuity and auditory acuity without or with correction
• Patients or patients' legal representative signing up the informed consent

Exclusion Criteria:

• Patients already diagnosed with neurocognitive disorder
• Patients with contraindications to ECT, including myocardial infarction, cerebrovascular disease, elevated intracranial pressure, intracranial angiomas, untreated bony fractures, cervical spine injury, pheochromocytoma, heart failure, sever valvular disease, deep vein thrombosis, etc.
• Patients with untreated substance abuse, including alcohol and illegal drugs
• Patients with unspecified psychiatric disorders
• Patients unable to cooperate