Tuesday, November 13, 2007

Getting your hippocampus to the finish line...intact!

The hippocampus is a brain structure responsible for memory functions. Unfortunately, hippocampi tend to shrink under certain stressful conditions such as aging, depression, Alzheimer's disease, schizophrenia, bipolar disorder, post-traumatic stress disorder, epilepsy, and head injury. One reason why hippocampal neurons wither under stress is that they are 'excited to death' through overstimulation by various neurotransmitters such as adrenalin and glutamate.

Prolonged stress can permanently affect memory; major depression is a known risk factor for the later development of Alzheimer's disease. There is good news, however, for beleaguered brains from the world of neuroscientific research.

According to researchers at Washington University in St. Louis, antidepressants not only relieve symptoms of depression, but they are neuroprotective as well. The investigators used magnetic resonance imaging to measure hippocampal volume in 38 depressed women and compared the values with 38 controls. On average, the depressed women had a history of five depressive episodes, some of which had not been treated with antidepressant drugs.

They found that hippocampal volume was reduced in depressed women. Furthermore, there was a direct correlation between hippocampal size and a history of untreated episodes of depression--the longer the women went without medication while seriously depressed, the smaller the hippocampus. Lead author Dr. Yvette Sheline notes that psychiatrists already recommend long-term treatment in persons prone to depression to prevent recurrences and goes on to add that "these apparent neuroprotective effects provide a further argument for at least strongly considering remaining on antidepressants."

Specific medications known to promote good health amongst the neuronal coeds living in the rat hippocampus include: Prozac (fluoxetine), lithium, tricyclic antidepressants such as amitryptilline and imipramine, dilantin, and valproic acid.

An interesting antidepressant tianeptine (brand name Stablon) is available in Europe and Latin America but not in the US. Research indicates that it is a more effective neuroprotective agent against hippocampal shrinkage than Prozac. It works by promoting the uptake of serotonin out of the gap or synapse between one brain cell and the next as opposed to Prozac which blocks the uptake and allows this neurotransmitter to work as long as possible. As many researchers name serotonin as one of the molecules that can excite a nerve cell to death, it makes sense that getting it out of the synapses of those sad and stressed might be good for their brains.

2 comments:

plague doctor said...

nice blog

Mauigirl said...

Fascinating! My father, who did get dementia in his late 80's, suffered from depression for the last 20 years or so of his life (plus had a couple of episodes in his youth before they had drugs). He had a lot of trouble finding a drug that worked so his hippocampus must have been shrinking.

Good thing I'm on Prozac! I never had major depression but I think I have the family tendency and decided a low dose of Prozac would be helpful - my doctor concurred and I've been very glad to be on it. Now I have another reason to be glad.