Deep Brain Stimulation
In the 1990s, the pioneering studies of Helen Mayberg and colleagues showed that stimulation of an area in the ventral part of the prefrontal cortex called the subgenual anterior cingulate gyrus (or Brodmann area 25, the part of the brain under the anterior corpus collosum) is associated with improvement in depression that resisted almost all other treatments. At the 65th Annual Scientific Convention of the Society of Biological Psychiatry this year, a number of research groups reported following up on Mayberg’s studies. The latest positive data on stimulation of Brodmann area 25 for treatment-resistant depression mirror new findings from other research groups who have stimulated the dopaminergic reward area of brain called the nucleus accumbens or ventral striatum with successful results.
In one of the first systematic studies intended to identify the best frequency and pulse width duration parameters for this type of intracranial stimulation in patients with treatment-resistant depression, researcher Swati Chavda of the University of Calgary reported that patients with depression improved when they were stimulated at 130 Hz (cycles/sec.) with a pulse width of 90 micro-seconds. In this double-blind study, depression neither improved nor worsened under other conditions, such as when the stimulation was turned off, when a low frequency (20 Hz) was used, or when much higher frequencies (185 Hz) with a pulse width of 420 micro-seconds were used.
Editor’s note: These data indicate that the positive effects of deep brain stimulation on clinical depression may depend on the frequencies used, with more intermediate stimulation parameters better than very high or very low ones. More clinical exploration is required in order to define optimal stimulation parameters for different brain regions. For the moment, this type of deep brain stimulation remains highly experimental, but is being pursued by a number of investigative groups in the US and Europe.
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