Question

Yes there is a link between depression and difficulty with memory recall. This area of cognition is interesting in that you literally see changes in someone's thought patterns when they are under new stress patterns. When this happens, as in the case of depression, parts of the brain associated with memory are impacted. What parts are these? How has deep brain stimulation helped in some cases?

Answer 1

The hippocampus, amygdala and prefrontal cortex are three brain areas, which aid the brain to label an event or a situation as stressful and fix an individual's reactions to it. These three areas are also related to one's memory. The hippocampus functions to keep memories and react to stress hormones present in the blood. Depression can weaken or reduce the size of the hippocampus. In the dentate gyrus region of the brain, new cells are generated during adulthood. Research has found that recurrence of stress can delay the generation of these new brain cells. It can also result in a reduction of brain cells in the hippocampus. The amygdala functions to keep emotional memories. It is known to become very active during the depression. Stressful experiences time and again can inflame the amygdala, thereby affecting emotional memories. The prefrontal cortex functions to regulate emotions, and plays an important role in decision-making and memory. This area is also known to reduce in size during the depression, thereby, possibly affecting memory.

Deep brain stimulation, abbreviated as DBS involves fixation of small electrodes in the brain area (specifically, nucleus accumbens) which controls mood, dopamine and serotonin release and motivation. This technique has been utilized in the case of 'chronic or treatment-resistant depression'. It involves persistent electrical stimulation in a specific brain area. The treatment is based on the premise that stable stimulating patterns will countermand distorted electrical patterns in the specific brain area. Deep brain stimulation is known to be a comparatively well-tolerated therapy. This treatment has brought about significant escalations in an individual's quality of life. The intervention is known to help the victims in planning and executing day-to-day activities, required to recover from depression. Some people have reported enhancement in dyskinesia, due to deep brain stimulation.