presynaptic imaging in major depressive episodes after covid-19

Conditions: Long COVID; Major Depressive Disorder; Major Depressive Episode

Summary: the goal of this observational study focuses on understanding and addressing a subset of persistent neuropsychiatric symptoms occurring within 3 months after mild to moderate covid-19 infection (covid-dnp). covid-dnp encompasses major depressive episodes (mde) with or without additional neuropsychiatric symptoms.

participants will undergo two positron emission tomography (pet) scans, one \[11c\]dtbz scan (for vesicular monoamine transporter 2 (vmat2) and one \[18f\]sdm8 scan (for synaptic vesicle glycoprotein 2a (sv2a)), as well as one magnetic resonance imaging (mri) scan. the main question\[s\] it aims to answer are: 1. the investigators will determine if vmat2 binding potential (vmat2 bpnd) is reduced in ventral striatum and dorsal putamen in covid-dnp. 2. the investigators will determine if sv2a total distribution volume (sv2a vt) is reduced in ventral striatum and dorsal putamen in covid-dnp

Eligibility criteria:
inclusion criteria: * new onset mde within 3 months after mild or moderate covid-19, with mde verified by the research version scid for dsm 5. see "positive covid-19 diagnosis" listed after inclusion/exclusion criteria for a description of how this is determined. * age 18 to 75. * good general physical health with no active medical conditions based on self-report (except migraine or pasc). exclusion criteria: * use of antidepressants in the previous month (6 weeks for fluoxetine). * use of stimulant medication affecting dopamine release in the previous month * use of antipsychotics in the previous month * history of neurological disease (except migraine, and pasc) based on self-report * use of medications or herbal products or natural health products with central nervous system effects in past 2 weeks based on self-report * presence of cigarette smoking in the past two months, based on self-report * lifetime diagnosis of severe substance or alcohol use disorder, or diagnosis of mild to moderate substance or alcohol use disorder in the past two years, based on self-report and verified by the research version of structured clinical interview for diagnostic and statistical manual-5 (scid-5-rv) * use of recreational drugs, including marijuana, in the past two months, based on self-report and verified by the research version of structured clinical interview for diagnostic and statistical manual-5 (scid-5-rv) * positive urine drug or cotinine screen at any timepoint during the study * history of psychotic symptoms secondary to schizophrenia, schizophreniform, bipolar disorder, or brief psychotic disorder prior to covid-19, based on self-report and verified by the research version of structured clinical interview for diagnostic and statistical manual-5 (scid-5-rv) * currently pregnant, based on self-report or positive pregnancy test at any timepoint during the study, in females (in our pet centre females up to 65 years of age are given a urine pregnancy test prior to every pet scan) * breastfeeding (for females) * current disorders of coagulation, blood or ongoing use of anticoagulant medication, based on self-report * claustrophobia, based on self-report * weight over 400lbs and height over 7ft (requirements for fitting in the scanners and hospital gowns) * presence of metal implant, object or electrical devices that are contraindicated for mri, based on self-report * severe allergic reaction to alcohol

Keywords: pet long covid major depressive disorder major depressive episode anhedonia dopamine neuron loss