Navigation Links
Depression could be evolutionary byproduct of immune system
Date:3/1/2012

Depression is common enough afflicting one in ten adults in the United States that it seems the possibility of depression must be "hard-wired" into our brains. This has led biologists to propose several theories to account for how depression, or behaviors linked to it, can somehow offer an evolutionary advantage.

Some previous proposals for the role of depression in evolution have focused on how it affects behavior in a social context. A pair of psychiatrists addresses this puzzle in a different way, tying together depression and resistance to infection. They propose that genetic variations that promote depression arose during evolution because they helped our ancestors fight infection.

An outline of their proposal appears online in the journal Molecular Psychiatry.

The co-authors are Andrew Miller, MD, William P. Timmie professor of psychiatry and behavioral sciences at Emory and director of psychiatric oncology at Winship Cancer Institute, and Charles Raison, MD, previously at Emory and now at the University of Arizona.

"Most of the genetic variations that have been linked to depression turn out to affect the function of the immune system," Miller says. "This led us to rethink why depression seems to stay embedded in the genome."

For decades, researchers have seen links between depression and inflammation, or over-activation of the immune system. People with depression tend to have higher levels of inflammation, even if they're not fighting an infection. Still, high levels of inflammatory markers are not an inevitable consequence of depression.

"The basic idea is that depression and the genes that promote it were very adaptive for helping people especially young children not die of infection in the ancestral environment, even if those same behaviors are not helpful in our relationships with other people," Raison says.

Infection was the major cause of death in humans' early history, so surviving infection was a key determinant in whether someone was able to pass on his or her genes. The authors propose that evolution and genetics have bound together depressive symptoms and physiological responses that were selected on the basis of reducing mortality from infection. Fever, fatigue/inactivity, social avoidance and anorexia can all be seen as adaptive behaviors in light of the need to contain infection, they write.

The theory provides a new explanation for why stress is a risk factor for depression. The link between stress and depression can be seen as the byproduct of a process that preactivates the immune system in anticipation of a wound, they write.

Similarly, a disruption of sleep patterns can be seen in both mood disorders and when the immune system is activated. This may come from our ancestors' need to stay on alert to fend off predators after injury, Miller says.

Their theory could also guide future genetic, physiological and clinical research on depression. In particular, the presence of biomarkers for inflammation may be able to predict whether someone will respond to various treatments for depression.

Miller and Raison are involved in ongoing research on whether certain medications, which are normally used to treat auto-immune diseases, can be effective with treatment-resistant depression.


'/>"/>

Contact: Kathi Baker
kobaker@emory.edu
404-727-9371
Emory University
Source:Eurekalert

Related biology news :

1. Coming soon: Self-guided, computer-based depression treatment
2. Depression during pregnancy can double risk of preterm delivery
3. Pregnancy hormone predicts postpartum depression
4. Chantix side effects no worse with depression history
5. Children seriously affected when a parent suffers from depression
6. Researchers take first look at the genetic dynamics of inbreeding depression
7. Mothers of multiple births at increased odds of postpartum depression
8. Team identifies a molecular switch linking infectious disease and depression
9. Genetic factors may predict depression in heart disease patients
10. Depression and anxiety disorders of adolescents are not the same thing
11. Early abuse tied to more depression in children
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:4/5/2017)... KEY FINDINGS The global market ... CAGR of 25.76% during the forecast period of 2017-2025. ... for the growth of the stem cell market. ... MARKET INSIGHTS The global stem cell market is segmented ... The stem cell market of the product is segmented ...
(Date:3/30/2017)... 30, 2017 The research team of The ... (3D) fingerprint identification by adopting ground breaking 3D fingerprint minutiae recovery ... of speed and accuracy for use in identification, crime investigation, immigration ... ... A research team ...
(Date:3/27/2017)... 27, 2017  Catholic Health Services (CHS) has ... Society (HIMSS) Analytics for achieving Stage 6 on ... . In addition, CHS previously earned a place ... an electronic medical record (EMR). "HIMSS ... of EMR usage in an outpatient setting.  This ...
Breaking Biology News(10 mins):
(Date:9/19/2017)... ... 19, 2017 , ... The latest generation of the AutoBlock, ... prep for metals digestion—the addition of acids and reagents. The accessory fits any ... is ideal for any laboratory performing their own unique metals digestion method. ...
(Date:9/19/2017)... ... ... CEO and founder, Dr. Bob Harman DVM, MPVM, is featured in an interview with Dr. ... Dr. Harman and Dr. Riordan met in 2003 and have remained in contact over ... cell therapy and a fast friendship was formed. , Dr. Harman has been a leader ...
(Date:9/19/2017)... 2017 ValGenesis Inc., the global leader in ... announce the strategic partnership with VTI Life Sciences (VTI). ... services using the latest technology available in the ValGenesis ... with efficient and cost-effective validation services using ValGenesis VLMS. ... ValGenesis VLMS system. ...
(Date:9/19/2017)... ... September 19, 2017 , ... ... (NYS DFS) cybersecurity regulations have transitioned into full force and effect. The ... the state (“Covered Entities”) to conduct an annual, professional, comprehensive cybersecurity risk ...
Breaking Biology Technology: