The Evolutionary Advantage of Depression - Brian Gabriel - The Atlantic

The Evolutionary Advantage of Depression - Brian Gabriel - The Atlantic

Interestingly, researchers at the University of Michigan's Molecular and Behavioral Neuroscience Institute discovered that individuals with major depressive disorder were more likely to have the mutated NPY gene. The normal NPY gene codes for higher levels of a neurotransmitter known as Neuropeptide Y, which appears to help ward off depression by increasing one's tolerance of stress. So the same mutated NPY gene that likely protected our ancestors against pathogens also increases our chance of developing depression.

Drs. Miller and Raison believe that acute (or severe but short-term) stress can not only lead to depression, but also jump-start the immune system. The physicians note that in the environments in which our ancestors lived, acute stress was often associated with the threat of physical harm or physical wounds. And unlike today, wounds readily led to infection and death. Therefore, Drs. Miller and Raison believe that evolution favored individuals whose immune systems operated under a "smoke-detector principle."

Although smoke detectors often react to false alarms (for me, burnt toast), if you removed the detector's battery and a real fire occurred, the consequences could be severe. Similarly, immune responses to acute stress are typically not necessary -- not every stressful situation results in a wound and infection. However, if our ancestors became wounded even a single time and didn't experience a piqued immune response, they might die from an infection.

The immune system acts like the I-O police in the body to find usually R germs that are hiding and camouflage themselves. They act like the middle of the food chain in the Roy animal kingdom and like the trunk of a tree in the Biv plant kingdom. A high stress environment can occur in an Iv-B economy because safety nets and insurance are much lower, people feel stress like a piece of flexing metal might experience stress until it cracks and shatter from chaos. 

Depression from stress can then be related to this this IV-B economy which also affects the immune system, it can also relate to a depressed economy where the weakened immune system has wasted so many resources from being overworked and false alarms. For example a person might become depressed because of chronic inflammation and being sick, auto immune problems, germs that the body can't get rid of because of this stress, etc. in the same way an economy can become depressed from this weakened and overworked I-O policing system, Iv-B and Oy-R interactions are secretive and deceptive giving continual levels of fraud such as in the financial system. The economy experiences this as chronic inflammation as a response to this fraud, it can be from mistakes with this I-O policing causing outrage in the V-Bi community like police shooting innocent people. 

The economy becomes like a zombie, it has this low grade infection of Iv-B secretive frauds and the government tries to compensate by putting it on life support with regular economic stimulus like a comatose patient kept alive with transfusions.

An I-O police can also have problems by not having this piqued or hyperactive immune response, this is like a neighborhood where the police are slow to respond to crime. it is also like how I-O regulators ignored many of the warning signs prior to the GFC. Such an immune system can also allow infections just as an overactive one can become exhausted then allow similar infections. In an economy the I-O police then need to be strengthened but also to become more selective and accurate at finding these deceptive criminal infections , this avoids auto immune responses of attacking innocent people which can exhaust it.  

It turns out that depression may not be a mere trade-off for a vigorous immune response. Dr. Miller suggests that depressive symptoms like social withdrawal, lack of energy, and a loss of interest in once enjoyable activities were actually advantageous to our ancestors. For example, a loss of energy might ensure that the body can leverage all of its energy to fight an infection. Also, social withdrawal minimizes the likelihood of being exposed to additional infectious agents. In this way, Drs. Miller and Raison note that "depressive symptoms are inextricably intertwined with -- and generated by -- physiological responses to infection that, on average, have been selected as a result of reducing infectious mortality across mammalian evolution."

Recently Dr. Miller and Dr. Raison completed a separate study in which they attempted to treat patients with "difficult to treat" depression with a novel drug infliximab. Infliximab works by disrupting communication between immune cells and consequently reduce inflammation. 

While infliximab did not significantly improve depression symptoms in the group being studied as a whole, it did reduce depression symptoms among a subset of study participants who showed elevated levels of inflammation. Inflammation was measured using blood tests for "C-reactive protein" (CRP). The higher the