The Impact of Working Memory and Reward Markers on DLPFC Activity in Treatment-resistant Depression

For those with depression where medication and psychotherapy have limited benefit, repetitive transcranial magnetic stimulation (rTMS) is an effective treatment. rTMS is a treatment that involves stimulating certain areas of the brain with magnetic field pulses. Over time, the magnetic field pulses can gradually change the activity level of the stimulated brain region. This can be helpful in treating some kinds of psychiatric and neurological disorder, including MDD.

"Research Interview: A study team member will meet the participant to ask questions regarding the degree of depression at the beginning of the study. This interview will take approximately 30 minutes.~Research Questionnaires: A study team member will ask the participant to complete questionnaires assessing the severity of the participant's depression, daily activities, personality/traits, and quality of life. Questionnaires will be completed via pen and paper at each visit. These questionnaires will take approximately 90 minutes to complete."

The participant will be asked to undergo a magnetic resonance imaging (MRI) scan to look at the structure and function of their brain. The functional MRI measures the level of blood flow to areas of the brain associated with mood and behaviour, and the participant will be asked to complete two behavioural games while they are in the scanner. During the scan, the participant will be required to lie on a table within the cylindrical tube of the MRI scanner in order to complete the scan. This will result in limited movement for the duration of the scan. The scan will take approximately 60 minutes, and there will be a recovery period for 40 minutes. The participant will be given instructions about these tasks outside of the scanner. This brain scan will happen at St. Michael's Hospital.

The participant will be asked to provide six 1mL saliva samples during the MRI scan and recovery period so that the investigators can measure molecular markers associated with depression. In order to provide the sample, the investigators will collect their saliva using a cotton swab and test tube. Each sample should take no more than 5 minutes.