Light Deprivation Causes Depression
The Guantanamo bay prisoners were made to wear these
Eye shields and ear muffs meant to deprive them of all
senses both Light and sound – allegedly as a form of torture.
The association between darkness and depression is well established. Now a March 25 study in the Proceedings of the National Academy of Sciences reveals for the first time the profound changes that light deprivation causes in the brain.
Neuroscientists at the University of Pennsylvania kept rats in the
dark for six weeks. The animals not only exhibited depressive behavior
but also suffered damage in brain regions known to be underactive in
humans during depression. The researchers observed neurons that produce
norepinephrine, dopamine and serotonin—common neurotransmitters
involved in emotion, pleasure and cognition—in the process of dying.
This neuronal death, which was accompanied in some areas by compromised
synaptic connections, may be the mechanism underlying the
darkness-related blues of seasonal affective disorder.
Principal investigator Gary Aston-Jones, now at the Medical
University of South Carolina, speculates that the dark-induced effects
stem from a disruption of the body’s clock. “When the circadian system
is not receiving normal light, that in turn might lead to changes in
brain systems that regulate mood,” he says.
Treating the rats with an antidepressant significantly ameliorated
brain damage and depressive behaviors. “Our study provides a new animal
system for antidepressant development. Many existing animal models
depend on stress.
Our model is a stress-free means of producing a depression. It might be
particularly relevant to seasonal affective disorder, but we think
that it is relevant to depression overall,” Aston-Jones says.
The article appeared on Scientific American.