DEPRESSION AND YOUR BRAIN

Regions near the front of the brain

The frontal lobes in people with depression, or those who are at risk for developing depression sometimes work a bit differently to people who don’t have depression. For example, in some people with depression, the left frontal lobe does not work as hard, compared with someone who does not have depression. This difference is thought to affect the way in which people with depression think about certain things. For example, people with depression often have trouble shifting their mental state and get stuck in negative ways of thinking, including focusing on sad or negative information more than joyous or positive information.

The frontal lobes may also be involved in the symptoms such as decreased appetite, body pain and excessive tiredness sometimes seen in depression. This is because the frontal lobes are linked with brain regions involved in the stress response and which represent our internal bodily states such as thirst, hunger and pain.

Regions near the front of the brain

Right hemisphere posterior regions (parietal regions)
People with depression or who are at risk for depression have reduced brain activity in the areas of the brain that are responsible for alertness and arousal (showing interest in things). This reduced activity is also thought to contribute to feelings of excessive tiredness and lack of energy that people with depression sometimes experience.

Regions deep down in the brain

Overactive amygdala
The amygdala is involved in processing negative/threatening information as well as the emotional significance of information. It is more active in people with depression, even at rest. Once activated in a person with depression, amygdala activity continues for longer periods than in a non-depressed person. This activity is heightened when encoding negative information into memory, which may explain why depressed people have trouble stopping negative thoughts which reinforce their depressed mood.

Subcortical reward pathways
There is reduced activity in reward pathways and dopaminergic motor systems related to symptoms of anhedonia (inability to feel pleasure and reduced motivation) and psychomotor slowing (slowing of thoughts and movements) in people with depression or at risk for depression.

Smaller hippocampus
The hippocampus is associated with memory. It works with the amygdala to provide context for learning emotional associations. People with depression have elevated levels of stress hormones which shrink the hippocampus and affect memory formation.

NEUROTRANSMITTERS AND DEPRESSION

Depression also influences neurotransmitters, causing increased or reduced levels. Read more about neurotransmitters and depression here.