Could a diabetes drug help schizophrenia patients lose weight?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Stable outpatients or inpatients aged 18-70 years, diagnosed with schizophrenia spectrum disorder, or major depressive disorder with psychotic features, or bipolar disorder (does not need to have psychotic features) * On maintenance treatment with an AP (stable dose for ≥3 months) * BMI must be ≥30 kg/m2, OR ≥27 kg/m2 with the presence of at least one weight-related comorbidity (treated or untreated): hypertension, dyslipidaemia, obstructive sleep apnea, or impaired fasting glucose, OR BMI ≥25 with individual having gained \>5% bodyweight in association with AP treatment * History of either failure to tolerate metformin or failure to lose ≥5% body weight over at least 16 weeks on the highest tolerated trial of metformin, and who are not currently being treated with metformin (minimum of 1 week metformin-free prior to study entry) Exclusion Criteria: * Patients with severe substance disorder other than tobacco or caffeine use disorder; only severe substance use disorder is exclusionary for cannabis use * Liver, or renal dysfunction * A positive drug urine screen other than cannabis as per PI discretion * Sexually active females of child-bearing age not on a regular contraceptive, or nursing or with a positive pregnancy test * Clinical or laboratory evidence of uncompensated cardiovascular, endocrine, haematological, or pulmonary disease * History of reactive hypoglycaemia * Treatment within 3 months, or failure to tolerate GLP-1RA * Type 1 Diabetes (T1D) or current diagnosis of Type 2 Diabetes (T2D), diagnosis of T2D on OGTT screen, or HbA1c \> 6.5% * Use of Health Canada approved weight-lowering agents, warfarin, coumarin derivatives, or medication with significant renal impact * Major medical or surgical event within the preceding 3 months * Personal or family history of medullary thyroid carcinoma or multiple endocrine neoplasia syndrome * History of pancreatitis or elevated amylase on screen * History of severe gastrointestinal disease, (i.e. gastroparesis) * Acute suicidal risk * Uncompensated thyroid disorder * History of heart rhythm disturbances, conduction system abnormalities, or evidence of clinically relevant abnormalities on screening ECG. * Any condition that interferes with the safe acquisition of MRI data such as metal implants, pacemakers, aneurysm clips, cochlear implants (only for the MRI component; can participate in the remainder of the trial) * History of gallstones with intact gallbladder or those at increased risk of gallbladder complications (with intact gallbladder)