Using brain imaging to diagnose depression
10 April 2008
There are no biological tests currently available to diagnose depression. Instead, health professionals rely on clinical signs and symptoms. Patients’ descriptions of their symptoms can be useful for assessing their emotional state, but some patients downplay or deny feeling depressed.
Now, Dr Cynthia Fu and colleagues from the Institute of Psychiatry, London have used brain imaging to distinguish between people with depression and those without, and have shown the potential use of brain imaging in predicting whether or not a patient will respond to treatment.
The researchers used functional magnetic resonance imaging - a technique that measures blood flow to different parts of the brain - to map the brain activity of 19 depressed patients and 19 healthy controls as they looked at pictures of sad faces. Twenty standard faces were morphed by computer to produce expressions showing low, medium or high intensities of sadness.
By analysing the patterns of activity over the whole brain while the subjects were looking at the faces, the researchers had a high rate of success distinguishing between healthy participants and those with depression. The researchers also showed that patterns of brain activity may also be able to identify which patients with depression will respond to antidepressant therapy and which will not.
Previous studies involving brain imaging have concentrated on the differences in brain activity between patients and healthy controls. The current research marks a shift from this comparison of two groups to asking whether someone belongs to the ‘depressed’ group or the healthy group.
The methods highlighted here could be particularly useful in patients less able to report their own symptoms, and could ultimately be used to diagnose and predict treatment response in other psychiatric conditions.
Image: Bottled III (Original); dailyinvention, http://www.flickr.com/photos/dailyinvention/247884640/
References
Fu CH et al. Pattern classification of sad facial processing: toward the development of neurobiological markers in depression. Biol Psychiatry 2008;63(7):656-62.