Predicting Cognitive Decline From Androgen Deprivation Therapy

Inclusion Criteria: Patient Participants- * Age 18 years or greater. * Fluent in reading, listening to, and writing English. * Current or prior diagnosis of prostate adenocarcinoma based on a pathology report or as documented in a medical oncology, urology, or radiation oncology note. * Access and ability to use a computer or mobile device with Internet connectivity to complete study procedures. * Telephone Montreal Cognitive Assessment (T-MoCA) of 16 or greater. * Eastern Cooperative Oncology Group (ECOG) performance status 0-2 (documented within past 3 months, otherwise patient-reported). Study partner participants- * Age 18 years or greater * Fluent in reading, listening to, and writing English * Identified by patient participant as a person who knows patient participant well, like a friend, family member or spouse. * Access and ability to use a computer or mobile device with internet connectivity to complete study procedures. Only the ADT cohort- * Anticipated to start ADT, which includes one of the following two treatments * Gonadotropin-releasing hormone (GnRH) agonist (e.g., leuprolide, goserelin, and others). * GnRH antagonist (i.e., degarelix or relugolix). * Anticipated to remain on ADT for at least 12 months. * Concurrent first-generation anti-androgens (e.g., bicalutamide, flutamide, nilutamide) and novel androgen-signaling inhibitors (e.g., abiraterone, enzalutamide, and apalutamide) are allowed. * Concurrent radiation is allowed. Only the PC cohort- * Has completed definitive local therapy (radical prostatectomy or radiation therapy) for localized prostate cancer at least 6 months prior to screening. * For radical prostatectomy: undetectable prostate-specific antigen (PSA) within 12 months of screening. * For radiation therapy: last PSA of \< 2.0 within 12 months of screening. Exclusion Criteria: Patient Participants- * Small cell prostate carcinoma (pure or mixed). * Receipt of ADT (GnRH agonist, GnRH antagonist, 1st-generation anti-androgen, or novel androgen signaling inhibitor) within 6 months before screening. ADT \>6 months prior to screening is allowed provided testosterone has recovered to 100 ng/ml or greater. * Concurrent or anticipated (at any point during first 12 months of ADT) non-hormonal, antineoplastic systemic therapy, such as chemotherapy. * Testosterone \<100 ng/ml. * Prior or concurrent brain metastases (no prior or screening imaging is required). * Major neurocognitive or psychiatric disorders, such as dementia or schizophrenia. * Prior or concurrent malignancy other than prostate cancer whose natural history or treatment has the potential to interfere with study assessments. Study partner participants- * None. Only the ADT cohort- * None. Only the PC cohort- * Any prior, concurrent, or anticipated use of any hormonal systemic therapy, including GnRH agonist, GnRH antagonist, 1st-generation anti-androgen, or novel androgen signaling inhibitor. * Any known or prior history of M1 prostate cancer (no screening imaging required). * Current or prior biochemical recurrence following American Urological Association guidelines for radical prostatectomy or American Society for Therapeutic Radiology and Oncology (ASTRO) guidelines for radiation therapy.