The Physiology Behind Depression During Starvation

Starvation has an incredible effect on an individual or animal's behavior and mental health. For example, rats when starved will be willing to endure increasing amounts of pain, through foot shocks, to get food. However, this willingness increases to a limit, at which the rat is either too weakened or too apathetic because of the severe starvation to reach the food.  

During "natural starvation" as in the case of the Siege of Leningrad, cognitive processes become directed more to objects and actions related to food, where normal activities and social interactions that are incompatible with food-seeking goals are repressed or eliminated. [1] This leads to amorality, apathy, and narrowing of intellectual interests.

Furthermore, during the siege, the stressors to individuals were not limited to just food, but also included the fear and violence of the war around them, as well as the excessive physical demands including digging trenches, sneaking supplies into the city, and clearing streets. These only compounded the desperation that came with food deprivation and hunger. 

While the depression that comes hand in hand with starvation was due to the environment, evacuation and access to ample food did not end the psychic trauma. Rather, the depression and behavioral changes from starvation can be long-lasting, much like the physical effects of starvation. This meant that individuals during recovery or in the decades afterward remained affected by their experience, and sometimes even hoarded their food despite the surplus around them.

[1] Keys, A., Brozek, J., Henschel, A., Mickelsen, O., & Taylor, H. (1950). The Biology of Human Starvation, Volumes I and II. University of Minnesota Press.