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Treating the other side of depression

Toronto, March 18, 2016

By Kendra Stephenson

Dr. Sakina Rizvi
Dr. Sakina Rizvi explains the areas of the brain involved in experiencing symptoms of anhedonia, the inability to feel enjoyment or pleasure. (Photo by Yuri Markarov)

At some point in their lives, roughly 11 per cent of the world’s population will experience depression. Despite being extremely common, depression remains one of the most difficult health conditions to successfully treat – but St. Michael’s Dr. Sakina Rizvi is determined to try.

Dr. Rizvi’s research focuses on treatment-resistant depression, where typical medications or therapies have not been effective in individuals with Major Depressive Disorder, or MDD. Specifically, her research has found a direct link between patients who have treatment-resistant depression and “anhedonia,” the inability to feel pleasure or experience reward.

“When we talk about depression, the common symptoms people identify are feeling sad, hopeless or worthless,” said Dr. Rizvi, who has a PhD in neuroscience. “These symptoms are linked to low serotonin levels, which most anti-depressant medications target. However, anhedonia symptoms are not always improved by targeting serotonin because other neurotransmitters, like dopamine, are involved in feelings of pleasure.”

To assess the relationship between anhedonia and treatment-resistant depression, Dr. Rizvi needed a screening tool for patients experiencing anhedonia to use in clinical settings. With limitations of existing options, she created and validated her own tool: the Dimensional Anhedonia Rating Scale, or DARS.

The simple self-reporting questionnaire allows patients to measure their experience with anhedonia. Patients identify various activities they previously sought out or enjoyed. They then answer a series of questions relating to pleasure, interest, effort and motivation to participate in these activities on a scale of “not at all” to “very much.” With a total possible score of 68, average scores of people without MDD fall within 44 and 68 on the DARS scale, whereas patients with MDD score within one and 40.

   
Did you know?

Mental health disorders are No. 5 on the global burden of diseases, just after cancer.

“I wanted to develop a good clinical tool as a proxy for the biological impairment that occurs in the brain when a person experiences anhedonia,” said Dr. Rizvi. “I looked at anhedonia symptoms in depressed patients in relation to dopamine receptors in the brain.”

This mapping of brain biology activity with symptoms could also eliminate the need for PET scans or MRIs when someone’s treatment isn’t working. Scans are expensive, with PET scans costing about $2,000 and MRIs around $500.

The DARS is highly accessible for patients and practitioners and can be used in real-time. Dr. Rizvi’s self-assessment questionnaire is free, fast and unique to the individual’s personal experience with depression.

The DARS tool is already being used by practitioners in clinical settings, with Dr. Rizvi’s research on anhedonia expanding to examine other areas of mental health, such as suicide risk and traumatic brain injuries.

About St. Michael's Hospital

St. Michael’s Hospital provides compassionate care to all who enter its doors. The hospital also provides outstanding medical education to future health care professionals in 27 academic disciplines. Critical care and trauma, heart disease, neurosurgery, diabetes, cancer care, care of the homeless and global health are among the hospital’s recognized areas of expertise. Through the Keenan Research Centre and the Li Ka Shing International Healthcare Education Centre, which make up the Li Ka Shing Knowledge Institute, research and education at St. Michael's Hospital are recognized and make an impact around the world. Founded in 1892, the hospital is fully affiliated with the University of Toronto.