Scientists have claimed to have discovered new and different methods to treat depression.
Depression treatments on the horizon include new medications, electrical and magnetic stimulation of the brain and long-term cognitive behavioral therapy for stress management.
For more than 50 years, depression has been studied and understood as a deficiency of chemical messengers, called neurotransmitters, which carry signals between brain cells.
Commonly used antidepressants are designed to either increase the release or block the degradation of three neurotransmitters - dopamine, norepinephrine and serotonin.
But drugs that target neurotransmitters, such as Prozac, Zoloft and Paxil, succeed in inducing the remission of depression in fewer than half of patients.
This has prompted researchers "to look beyond neurotransmitters for an understanding of depressive disorders," authors Murali Rao from Loyola University and Julie M. Alderson a resident at East Liverpool City Hospital in Ohio, wrote.
New theories of depression are focusing on differences in neuron density in various regions of the brain; on the effect of stress on the birth and death of brain cells; on the alteration of feedback pathways in the brain and on the role of inflammation evoked by the stress response.
Chronic stress is believed to be the leading cause of depression, the authors wrote. Long-term stress harms cells in the brain and body.
Stressful experiences are believed to be closely associated with the development of psychological alterations and, thus, neuropsychiatric disorders.
In conditions of chronic stress exposure, nerve cells in the hippocampus, a part of the brain involved with emotions, learning and memory formation, begin to atrophy.
The new depression theories should not be viewed as separate entities because they are highly interconnected, and integrating them provides for a more expansive understanding of the pathophysiology of depression and biomarkers that are involved, Rao and Alderson wrote.
Such biomarkers are molecules in the body that can be indicators of depression. The authors identify more than a dozen potential biomarkers depression, including monoamine regulators; proinflammatory cytokines and other inflammatory mediators; mediators of glutaminergic activity and GABAergic activity; and regulators of neurogenesis.
The study is published in the journal Current Psychiatry.