Depression affects the brain

As if feeling better weren't incentive enough to pursue treatment for clinical depression, it is also now understood that chronic depression causes irreversible damage to parts of the brain.

We have known for some time that depression is associated with cognitive impairment. Difficulties with memory, concentration, decision making, and focusing have long been understood as some of the symptoms of the condition.

Recent research using brain imaging, autopsy and neuropsychological testing now suggest that some of these symptoms are likely the result of changes to the function and structure of the hippocampus in the brains of depressed individuals.

The hippocampus is a structure in the brain that is very important for tasks such as memory and concentration and it is very sensitive to stress. This structure is known to be involved in several other brain disorders such as Alzheimer's and recurrent major depression has long been known as a risk factor for Alzheimer's.

What recent studies have found is that hippocampal volume is decreased in those with recurrent depression. This loss of volume appears to be related to the total duration of depression and this is grounds for optimism since it implies that early treatment of the depression could prevent further loss of volume in the hippocampus.

Stress seems to affect this area of the brain by decreasing levels of a protein that is essential for the growth of brain cells - neurogenesis. Decreases in this protein, called brain derived neurotrophic factor (BDNF), lead to cell death and the shrinkage of the hippocampus.

Although more research is still needed, it appears that mutations to the gene that produced BDNF may make some people more susceptible than others to the effects of stress on this protein.

Some animal studies suggest that the effects of antidepressants depend on neurogenesis and that they protect against the effects of stress. Neurogenesis is also increased by antidepressants, regular exercise and certain kinds of intellectual activity. It is reduced by stress, age, adrenal steroids and drugs of abuse.

It is also known that antidepressant medications increase the level of BDNF in the brain and thus seem to prevent further shrinkage of the hippocampus.

Although antidepressants seem to prevent further hippocampal shrinkage, they may not be able to fully reverse the loss of neurons that has already occurred. This is consistent with the usual advice that it is better to prevent future episodes of depression than to let them happen and then attempt to treat them.

For those who are depressed it is important to get treatment early and not to wait for spontaneous improvement. It may occur but at a cost of gradual progressive loss of hippocampal volume that eventually will have irreversible cognitive effects.

Speak with your doctor about options in the treatment of depression. Not only will you protect your brain, but you can also feel better and regain enjoyment in life.

Okanagan Clinical Trials currently has ongoing studies of investigational medications in the treatment of depression. If you are an adult experiencing depression, you may be eligible to participate. Contact our office for more information or to schedule a free, no obligation medical assessment.


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