Those suffering from depression typically have more immediate concerns than the long-term effects of depression on the body. However, researchers have found a link between depression and the size of the sufferer’s brain. A certain section of the brain is believed to shrink in victims suffering from the disease.
Glucocorticoids and the Damage They Cause
High levels of depression have been associated with an increased level of cortisol (a steroid hormone) in about half of all cases. Excess cortisol has been linked to damage to the hippocampal neurons, an area of the brain important to memories. However, recent studies show that this excess may also have an effect on brain size.
One study tested patients with varying levels of depression and compared them to patients with no instances of depression. The study found a 19 percent reduction in the size of the left hippocampus in patients with recurring severe depression. There was no difference in other sections of the brain.
Another study compared major depressive patients in remission to those who had never suffered from the condition and found reduction in size of both the left and right hippocampal regions. The study noted that reduction in size of the hippocampus corresponded to the number of days a subject spent depressed, concluding that depression is associated with reduction in size of the hippocampus. The study also concluded, as did the previous study mentioned, that this reduction could lead to further depressive episodes
Theories About the Reduction
While scientists have not yet pinned down the exact cause of the reduction, high levels of glucocorticoids may be the cause of the damage. In fact, researchers theorize that over time, repeated episodes of depression may cause the hippocampal section of the brain to further atrophy, leading to increased episodes of depression.
Another theory is that a reduction in neurotrophins could cause the hippocampal size reduction. Or, the hippocampus may be smaller in severe depression patients from birth, possibly leading to the condition later in life. However, further studies should be made into the relationship between glucocorticoids and hippocampal shrinkage.
Hippocampal Atrophy Effects on Depression Patients
The hippocampus is the section of the brain associated with memory recall and emotions. The shrinkage problem appears to be most marked in cases of depression that last for multiple days and recur frequently. This shrinkage is generally minor and is usually connected only with an increased risk of further depressive episodes. However, the brain size showed noticeable changes in the hippocampal region in severe cases of depression that last for years—especially in those whose depression started in childhood.
In addition to a predicted increase in incidents of depression, this reduction in size of the hippocampus is linked to possible memory loss. Researchers reference Alzheimer’s patients, who have also been found to have hippocampal shrinkage. While memory loss is not as severe in depression patients, researchers have found that test patients have a noticeable loss in verbal memory—meaning they have an inability to remember words. Visual memory has not shown impairment in studies of depressive patients.
Treatment for Depression and Brain Shrinkage
Depression treatment like Prozac can help combat this reduction by regulating the serotonin. More studies need to be done on the effects of antidepressants on glucocorticoids, but taking these medications could help prevent permanent damage.
A study by a group of researchers at the National Institute of Mental Health in Maryland found an increase in memory retention after just seven months of treatment with the antidepressants Prozac or Effexor. Even better news is that these treatments have shown to reverse shrinkage that has already occurred in study patients.
This research emphasizes the importance of treatment for those patients suffering from depression. Not only does treatment help keep symptoms at bay and improve quality of life, it may be the key to preventing and even reversing permanent brain size change in patients with severe recurring depression.