Sad Study Is First To Give Us A 'Snapshot' Of What's Happening Inside Our Brain
Toronto, Ont. -- A scientist from the University of Texas Health Science Center at San Antonio, now with Baycrest Centre for Geriatric Care in Toronto, has used imaging techniques to show for the first time how two key areas of the brain interact with one another when depression is affecting cognitive ability.
The clinical study, to be published in the May issue of the American Journal of Psychiatry, has identified a reciprocal or see-saw relationship between the emotional (limbic) and cognitive (cortical) areas of the brain when people are feeling depressed.
Dr. Helen Mayberg, with her colleagues Drs. Mario Liotti and Stephen Brannan, conducted the study at the Research Imaging Center at the Health Science Center in Texas. Dr. Mayberg moved to the Rotman Research Institute at Baycrest earlier this year to expand this area of research.
The study monitored the brain activity of healthy and severely depressed adults during sad and neutral states. When healthy subjects experienced temporary intense sadness, blood flow increased in the ventral limbic and paralimbic sites, otherwise known as the primitive regions of the brain generally associated with emotion. At the same time, blood flow decreased in dorsal cortical regions, areas previously shown to mediate attention, cognition and reasoning.
An identical inverse relationship was identified when depressed patients recovered from a long-term depressed mood with both anti-depressant medication and non-drug therapy. In these patients, metabolism increased in cortical regions and decreased in limbic regions, hence the see-saw analogy.
It's long been known that feeling depressed can impair thinking, and that the emotional (limbic) and cognitive (cortical) parts of the brain are somehow interacting with one another. But until now scientists have not been able to generate a snapshot of how this neural interplay works.
"Specific relationships between limbic (affective) and neocortical (cognitive) brain regions have long been theorized. These findings provide important data confirming the generally recognized interaction of negative mood and altered attention in health and disease," says Dr. Mayberg, who holds the Sandra A. Rotman Chair in Neuropsychiatry with the University of Toronto and Baycrest Centre.
"These findings also have broad implications for developing new therapeutic strategies to treat disorders where both mood and cognition are affected. Furthermore, these findings provide a plausible explanation for why psychotherapy and drugs are often equally effective in treating depressed patients."
The two subject groups in the study were eight healthy women and eight men with severe depression. Using brain imaging technology, two experimental alterations of mood were investigated: temporary intense sadness provoked in healthy volunteers, and treatment of clinically depressed patients.
Participants in the healthy group were asked to prepare a personal script of two sad experiences and then recount them with the investigator during which their regional cerebral blood flow was measured. The eight depressed patients were treated in the hospital with anti-depressant medication and psychotherapy. Changes in regional glucose metabolism were measured.
The study was conducted using a brain imaging technique called positron emission tomography (PET), which constructs computerized multi-colored images showing where maximum activity is occurring in the brain.
Funding for the study was provided by the National Institutes of Mental Health, the Charles A. Dana Foundation, Eli Lilly and Co., and the National Alliance for Research on Schizophrenia and Depression.
Journal
American Journal of Psychiatry