(23-01-14) Early head trauma can cause depression later in life

by Sharon Heller, PhD

(NaturalNews) Some people suffer from depression their whole lives. But others will suddenly become depressed in their 40s, 50s or 60s. Why would this suddenly happen? One reason, a new animal study suggests, relates to concussions experienced as young adults and an immune challenge from the head injury.


Of Mice and Melancholy
In a study published online in the journal Biological Psychiatry, researchers compared mice that had experienced moderate traumatic brain injury (TBI) to uninjured mice.

Initially, the injured mice showed some coordination problems that resolved within a week and some signs of depression that improved within one month. These symptoms were explained by neuroinflammation that occurs after a TBI.

But 30 days after the injury, when the researchers examined the brains of the injured mice, they found that the immune cells of the injured mice had remained on high alert since the injury.


Surprising Long-Term Effects
What was surprising in this study was the nature of the concussions and unexpected sequelae. The concussions suffered by the mice were caused by diffuse, or spread-out, trauma to the brain, from which people and animals recover fairly quickly. Typically, neither animals nor humans show any problems with thinking or moving about a week after such an injury to the brain, and full recovery is assumed. Yet, unknowingly, inflammation in the brain continues, and when later faced with an immune challenge, excessive inflammation results.

What does inflammation have to do with later depression? 30 days after the TBI, the mice were injected with lipopolysaccharide, the dead, outer cell wall of bacteria that stimulates an immune reaction in animals. Within 24 hours following the injection, the brains of the injured mice had dramatically higher levels of two inflammation-related proteins than did the brains of normal mice, and the injured mice were much less social than uninjured mice. Within 72 hours following the injection, the injured mice had little interest in sugar water, avoiding a typical pleasurable activity, and showed increased resignation, or a sign of "giving up." The mice were depressed!


Treating Inflammation-Related Depression
These findings have implications not only for possible causes of late onset depression in humans but also for treatment. As these depressive symptoms are likely inflammation-related, they may not respond to common antidepressants. The researchers are investigating potential treatments that could either prevent a high-alert immune response immediately after injury or later reverse the high-alert characteristics of these cells.

Sources for this article include:

http://www.sciencedaily.com

http://www.journals.elsevier.com

http://science.naturalnews.com

http://science.naturalnews.com

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