Investigating Functional Changes in the Frontotemporal Cortex of Patients With Major Depressive Disorder Following Electroconvulsive Therapy or Magnetic Seizure Therapy Using Functional Near-infrared Spectroscopy (fNIRS)

Investigating Functional Changes in the Frontotemporal Cortex of Patients With Major Depressive Disorder Following Electroconvulsive Therapy or Magnetic Seizure Therapy Using Functional Near-infrared Spectroscopy

Against the clinical backdrop of the growing global burden of neuropsychiatric disorders, the rapid rise in depression prevalence, and the frequent association of these conditions with cognitive impairment, this study highlights the limitations of current cognitive assessment tools-such as their time-consuming nature and lack of specificity-and underscores the urgent need to develop simple and efficient assessment methods. In terms of treatment, modified electroconvulsive therapy (ECT) and magnetic seizure therapy (MST) are rapidly acting neuromodulation therapies; however, their effects on cognitive function and underlying brain mechanisms remain controversial, and there is a lack of direct comparative studies. Functional near-infrared spectroscopy (fNIRS) technology can non-invasively monitor changes in cerebral hemodynamics, providing a powerful tool for assessing brain function before and after treatment. Therefore, this study aims to combine resting-state and task-based fNIRS with multidimensional cognitive and emotional assessments to systematically compare the effects of ECT and MST on frontal-temporal cerebral hemodynamics. We seek to clarify the differences in brain function regulation between the two treatment modalities and their association with improvements in cognition and mood, with the goal of providing scientific evidence to elucidate the brain mechanisms underlying neurostimulation therapies and optimize individualized treatment plans.

The global burden of neuropsychiatric disorders continues to rise. Depression ranks among the leading causes of global disease burden as measured by years lived with disability, and its prevalence increased by more than 36% between 2010 and 2021. Depression manifests not only as core symptoms such as low mood and loss of interest but is also commonly accompanied by cognitive impairment, frequently presenting as declines in executive function, attention, memory, and information processing speed. The severity of these cognitive deficits directly impacts patients' treatment response, recovery of social functioning, and long-term prognosis, making them a key factor limiting patients' return to normal life.

However, there remains a significant gap in the clinical emphasis placed on and assessment of cognitive symptoms. Although existing cognitive assessment tools include subjective self-report questionnaires, individual neuropsychological tests, and battery tests, they generally have limitations: some tools are time-consuming and difficult to adapt to the needs of rapid clinical screening; others lack sufficient clinical evidence and normative data to support their use, resulting in insufficient diagnostic specificity and an inability to accurately match the cognitive impairment characteristics of different neuropsychiatric disorders. Therefore, in conjunction with advancements in neuroscience and technology, the development of simple, efficient, and specific cognitive assessment tools and brain function monitoring methods has become an urgent clinical need.

In the therapeutic field, neurostimulation therapies have gradually emerged as an important complement to pharmacotherapy and cognitive-behavioral therapy. Among these, modified electroconvulsive therapy (ECT) and magnetic seizure therapy (MST) are widely used in the treatment of depression due to their rapid onset of action and significant efficacy. As a classic neurostimulation method, ECT can rapidly alleviate depressive symptoms, particularly suicidal ideation; however, its short-term effects on cognitive function and the underlying brain mechanisms remain controversial. MST, on the other hand, induces localized cortical epileptiform discharges through rapidly changing magnetic fields and is characterized by high targeting precision; however, its safety profile and modulatory effects on brain function require further investigation. Yet, most studies in this field focus on a single treatment modality, lack sufficient comparative analysis of brain functional changes between resting and task states, and, more critically, lack direct comparative studies between ECT and MST.

The development of functional near-infrared spectroscopy (fNIRS) technology provides a powerful tool for addressing these issues. By monitoring changes in the concentrations of oxygenated and deoxygenated hemoglobin, this technology can non-invasively and in real-time reflect regional cerebral blood flow and functional activation levels, making it particularly suitable for assessing dynamic changes in brain function during cognitive tasks. Existing fNIRS studies have confirmed that in patients with depression, the oxygenated hemoglobin response in the prefrontal cortex is significantly lower than that in healthy controls during verbal fluency tasks and working memory N-back tasks, and this abnormality is associated with the severity of depression. During ECT treatment, the oxygenated hemoglobin response in the prefrontal cortex may further decrease; however, the correlation between this change and improvements in mood or cognitive function remains unclear. Furthermore, existing studies have primarily focused on task-based brain function analysis, with limited attention paid to changes in cerebral hemodynamics during rest before and after neurostimulation treatments, and a lack of systematic comparisons between the effects of ECT and MST on frontal-temporal lobe brain function.

Against this backdrop, this study focuses on the effects of ECT and MST on fronto-temporal cerebral hemodynamics. Through a dual-dimensional assessment of both resting-state and task-state conditions, combined with fNIRS technology and multidimensional cognitive and emotional assessment tools, the study aims to clarify the differences in the regulation of fronto-temporal brain function between the two treatment modalities and to reveal the associations between pre- and post-treatment changes in cerebral hemodynamics and improvements in cognitive function and emotional symptoms. The findings will provide new evidence for elucidating the neural mechanisms underlying neurostimulation therapies, offer a scientific basis for optimizing treatment protocols and developing personalized treatment strategies, and ultimately contribute to improving treatment outcomes and patient prognosis for neuropsychiatric disorders.

Inclusion Criteria:

• A depressive episode diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), confirmed by two psychiatrists;
• Meets the treatment criteria for ECT or MST;
• At least 5 years of education, with no significant hearing or visual impairments;
• Voluntary participation in this study, with a signed written informed consent form, and willingness to cooperate with the collection of general demographic information, neuropsychological testing, and fNIRS resting-state and task-based data acquisition.

Exclusion Criteria:

• Co-occurring mental disorders (such as substance use disorders or schizoaffective disorder);
• Severe physical illness;
• History of neurological disorders (such as traumatic brain injury or dementia);
• Low educational attainment;
• Receipt of ECT or MST treatment within the past six months.