Center of Excellence in Co-Occurring Medicine | Contact Us Now 503.832.0945
Portland's Psychiatric and Addiction Specialists | 503.832.0945
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Meet the Team
Gilbert M. Simas, MD, MBA
Founder and Director of Medical Services
Dr. Simas is board-certified in Psychiatry and Addiction Psychiatry. He offers compassionate, personalized care for each patient. Dr. Simas is experienced in providing both outpatient and inpatient psychiatric care. His special expertise is in the treatment of co-occurring mental health and substance use disorders. Dr. Simas opened the Center of Excellence in Co-Occurring Medicine in 2015 to better meet the tremendous community need for psychiatric care and addiction services. He is experienced in treating opioid use disorder with Suboxone®, an effective medication for suppressing withdrawal symptoms and decreasing cravings. Dr. Simas is also a pioneering provider of telepsychiatry services.
Please note: Dr. Simas is not taking new patients at this time.
Timothy Holt, MSN, PMHNP-BC
Mr. Holt is a board-certified Adult Mental Health Provider/Clinical Specialist with more than three decades of experience in healthcare. He has practiced as a Psychiatric Mental Health Nurse Practitioner since 1996. Mr. Holt has worked in both outpatient and inpatient settings — in urban and rural environments. He is an expert in diagnosing, treating, and managing a broad range of psychiatric conditions. His treatment approach includes a combination of psychiatric medication and cognitive behavioral therapy.
Mr. Holt is in network with the following insurance plans: Aetna, Cigna, Moda Health, PacificSource, Providence Health Plan (with behavioral health coverage through Optum), Regence Blue Cross Blue Shield, and United Healthcare (with behavioral health coverage through Optum).
Jennie Peterson, MSN, PMHNP-BC, CARN-AP
Ms. Peterson is a Psychiatric Mental Health Nurse Practitioner with an advanced practice certification in Addictions Nursing. She specializes in assessment, diagnosis, treatment, and co-occurring psychiatric conditions. Ms. Peterson works diligently to develop trusting relationships with her patients. Prior to joining the Center of Excellence, she managed the addiction consult service with UAB Hospital in Birmingham, Alabama. She also provided outpatient care and medication-assisted treatment for patients with co-occurring psychiatric conditions.
Her career began in Portland, Oregon, in 1998, when she graduated from Oregon Health & Science University with a bachelor’s degree in nursing. Ms. Peterson worked in the Pediatric Intensive Care Unit at Legacy Emanuel Children’s Hospital for seven years before transitioning to hospice care, where she had the privilege of providing support and comfort to patients and their families. She has always been interested in psychiatry, but she did not pursue her dream until life events brought her to Birmingham. Ms. Peterson worked as a registered nurse in the Addiction Recovery Program at UAB Hospital while pursuing her master’s degree with a specialty track for Psychiatric Mental Health Nurse Practitioner — across the life span. She is a member of the International Nurses Society on Addictions (IntNSA) and is very passionate about caring for patients who struggle with mental health and addiction.
Ms. Peterson enjoys spending time with her children and pets. An avid nature lover, she also relishes outdoor adventures.
Madelyn Keller, CNA
Lead Patient Care Coordinator
“When you’re here, you can be who you are.” That’s what Maddy appreciates most about the Center of Excellence. “No one needs to worry about mental health stigma at our clinic,” she says. “We are on this journey together, as human beings. I really care about each patient’s life and story.” Maddy leads the Patient Care Team in assisting providers, responding to patient requests, and finding ways to improve the patient experience every day. Prior to joining the Center of Excellence, Maddy coordinated medication distribution for an assisted living community. She spends her free time exploring the natural wonders of the Pacific Northwest.
Maddy’s favorite inspirational quote:
“Somewhere, something incredible is waiting to be known.”
— Carl Sagan
Wendy Zamora MSN, PMHNP-BC
Wendy’s career in nursing started in 1992 when she graduated with her BSN from Oregon Health Sciences University. Over the next twenty-plus years she worked in many nursing specialties; the most time spent in primary care and community health. A lifelong learner, Wendy decided to pursue psychiatry, earning her MSN from Gonzaga University in 2016. Practicing as a Psychiatric Mental Health Nurse Practitioner has provided Wendy an opportunity to take her care for individuals to the next level. Establishing a therapeutic relationship is of primary importance to Wendy, as well as integrating healthy lifestyle choices in with pharmacotherapies.
A native Oregonian, Wendy has an active lifestyle. She enjoys walking her 2 dogs, hiking, fitness activities, flower gardening, reading and knitting. Her favorite place in the world is the Oregon Coast where she goes when she wants to feel centered.
Patient Service Coordinator
Jackie is dedicated to providing the best service to patients, whether she is scheduling an appointment, verifying insurance benefits, or setting up a payment plan. Her sense of humor and willingness to go the extra mile will make you feel welcome and safe. “The best part of my job is the time I spend with patients — listening to their stories, making them feel comfortable, and reassuring them that they are in good hands with our providers,” Jackie explains. “Our team is here to help patients in any way we can, in a supportive and non-judgmental environment.” Prior to joining the Center of Excellence, Jackie worked as a senior customer service representative. In her free time, Jackie enjoys gardening and spending time with family.
Jackie’s favorite inspirational quote:
“It’s not about perfect. It’s about effort. And when you bring that effort every single day, that’s where transformation happens. That’s how change occurs.”
— Jillian Michaels
Tana works diligently to ensure patients receive the best service at every point of contact — and that the front office team has the tools and support they need to fulfill the clinic’s standards of excellence. She is a champion for continuous improvement, open communication, and meaningful change that meets the needs of patients and our community. Prior to joining the Center of Excellence, Tana worked in a variety of roles, including Confirmation Analyst for a renewable energy organization and Senior Administrative Assistant at a large insurance carrier.
Outside of the office, Tana delights in spending time with her family. She also enjoys gardening and international travel.
Tana’s favorite inspirational quote:
“If we amplify everything, we hear nothing.”
— Jon Stewart
Director of Operations
Kerri oversees clinic operations — with the goal of providing compassionate, expert care to every patient, during every visit. Kerri works tirelessly to ensure that you receive superior care in a supportive and non-judgmental environment. She also leads the clinic’s technology initiatives, including our new telepsychiatry service.