Depression is associated with widespread changes in brain structure and function. Here are a few examples:
1. A strong body of research shows that people with depression often have a smaller hippocampus . The hippocampus is well known to be important in memory as it processes memories for long term storage. The hippocampus, however, also connects to the many areas of the brain which regulate how we feel and respond to stress. For example, the hippocampus connects to the amygdala which controls our experience of fear.
Depression is regarded as a stress related illness and people with depression often gave higher levels of circulating stress hormones such as cortisol. Cortisol is toxic to the cells within the hippocampus and excess cortisol is a hypothesised mechanism for why people with depression have a smaller hippocampus . Interestingly, even in people who have not yet experienced significant stress, a smaller hippocampus increases the risk for acquiring a stress related psychiatric disease .
- Good news: The hippocampus is a relatively unique area in the brain which can grow new neurons. Antidepressant medication has been shown to increase the volume of the hippocampus by promoting neurogenesis (i.e. the growth of new brain cells) . It is interesting to note that the growth of new hippocampul neurons takes up to six weeks to complete; and this about the same time it takes for most monoaminergic antidepressants (e.g. SSRI) to take full effect.
2. People with depression process information differently, often with a negative bias.
– Lukas Wardrop