The study aims to use machine learning to predict the occurrence of episodic and autobiographical memory deficits as well as treatment response following a course of electroconvulsive therapy. Additionally, the neurophysiological correlates of the cognitive effects after a course of ECT will be investigated.

Therefore, structural, resting-state and diffusion tensor images will be collected within one week before the first and after the last ECT treatment from severely depressed patients. Standard measures of cognitive function and specifically episodic as well as autobiographical memory will also be collected longitudinally and used for prediction. The study consists of 60 ECT receiving inpatients suffering from major unipolar or bipolar depression, 60 medication-only controls and 60 healthy controls.

Due to the immense disease burden of major depression and unsatisfactory response to standard pharmacological and psychological treatments, the need for treatment alternatives is evident. Electroconvulsive therapy (ECT) remains to be the most efficacious treatment known for treatment-resistant depression. However, although many studies show response rates above 70%, ECT can be considered vastly underused. Reasons contributing to this phenomenon may include stigma, regulatory restrictions, limited medical training, safety and side-effect concerns, or reluctance among professionals to recommend ECT. Most of these reasons have already been refuted or put into perspective by psychological and neuroscientific studies (e.g. ECT causes brain lesions) and most cognitive deficits related to the ECT course seem to fade after several weeks of discontinuation.

Still, in terms of the tolerability, memory disturbances remain the most problematic effect of ECT. Besides subjective reports from patients after a course of ECT, experimental studies have also found evidence of episodic and autobiographical memory impiarment attributable to ECT. The origins of these effects are still largely unknown and remain a goal for further research.

It has now been shown that structural T1 weighted MR-images can be used to predict the response to a course of ECT via machine learning. Therefore, this study aims to use machine learning to predict the occurrence of episodic and specifically autobiographical memory deficits arising within a course of electroconvulsive therapy based on MR-images collected within one week before the first ECT treatment from severely depressed patients. Additionally, the neurophysiological correlates of the cognitive effects modulated by a course of ECT will be investigated longitudinally through the use of structural, resting-state and diffusion tensor images. The study consists of 60 ECT receiving inpatients suffering from major unipolar or bipolar depression.

If successful, this line of research should lead to a better tolerability of ECT by aiding in the complex decision making process involved in prescribing ECT as well as the parameter setting within a treatment course (e.g. uni- vs. bilateral).

Inclusion Criteria:

• The duration of the current depressive episode is at least four weeks
• The duration of the current depressive episode is less than five years
• Inpatients of the psychiatric clinic of the University Hospital Bonn and eligible for ECT because of major depressive disorder or major depressive episode in bipolar disorder (according to DSM-5 criteria)
• Score on HDRS 28 ≥ 20
• Ability to understand the purpose of and procedures required for the study and willingness to consent to participation
• Meeting of standard medical prerequisites for ECT (judged by staff psychiatrist)
• Ability to speak and understand the german language

Exclusion Criteria:

• No lifetime occurence of a personality disorder
• Current (or within the last year) posttraumatic stress disorder
• Schizophrenia or any other psychotic disorder except for psychotic depression
• Severe somatic or neurological condition (e.g. stroke)
• Head trauma resulting in unconsciousness for more than 5 minutes
• Pregnancy
• Maintenance ECT or ECT received during the last 6 month
• Subjects who do not consent to be informed of incidental findings that could have healthcare implications
• Drug or alcohol dependence (<6 month before ECT)
• Is currently enrolled in a study with an investigational study drug
• Has any condition that, in the opinion of the investigator, would compromise the wellbeing of the subject or the study or prevent the subject from meeting or performing study requirements

Inpatients at the psychiatric hospital of the University Hospital Bonn. The patients diagnosis of major depressive disorder will be verified via the structured clinical interview for DSM-5. ECT protocol in line with international standards administered by a staff psychiatrist.

Additionally, a medication-only and a healthy control sample are included in the study.