The purpose of this research study is to examine changes that occur in the brain over time in participants with Major Depressive Disorder (MDD) compared to participants without MDD.

Individuals who meet the following criteria may qualify for this study.

Inclusion Criteria:

• 35+ years old
• Speak and write English
• Eligible for MRI and PET scans

Exclusion Criteria:

• Pregnancy or breastfeeding
• Serious medical conditions
• Serious neurological conditions (i.e., brain tumors, head injury with loss of consciousness for 5+ minutes)
• Substance use disorders (except marijuana and nicotine) in the past year
• Diagnosis of ADHD, pervasive developmental disorders, eating disorders, or psychotic disorders
• REM sleep disorder
• History of a bleeding disorder or currently taking anticoagulants
• Blood donation in the past 8 weeks

If eligible, participants will complete between 3-8 visits in New Haven, CT, including:

1. Screening that can be done via Zoom. The physical, bloodwork, and EKG are in person.
2. PET scan visit.
3. fMRI and MRS scan visit. Other components such as EEG may be done on the same day or require a separate visit.

1 year later, participants will return for a follow-up visit involving computer games and questionnaires.

2-3 years later, participants will repeat the study.

Compensation up to $600 or more will be provided for completing the study.

There is no cost to participate in our research study.