Depression is a mental disorder characterized by a lack of pleasure in familiar activities, a sad mood, and cognitive/somatic changes that limit functioning. Psychologists use three different approaches while explaining the etiology (origin) of depression: biological, cognitive, and sociocultural.
Depression has a biological etiology
Recent developments, including the sequencing of the human genome and the advancement of brain imaging, technologies allowed psychologists to explain depression from a biological perspective. This school of thought argues that biological factors such as genetics and hormone/neurotransmitter levels cause depression.
Genetic predisposition explains the etiology of depression
Genetic researchers argue that there is an increased chance of developing depression based on one’s genetic makeup. This genetic predisposition results from specific genetic variations that are inherited from parents. Many twin, family, and adoption studies support this view.
Low serotonin levels in the brain causes depression
Serotonin is an inhibitory neurotransmitter involved in regulating mood, sleep, and cognition. The serotonin hypothesis states that depression results from a chemical imbalance in serotonin levels. The success of serotonin-increasing drugs in treating depressive symptoms supports this hypothesis.
The cortisol hypothesis states that depression is the result of the cessation of neuron birth in the hippocampus and other neural networks related to serotonin, dopamine, and norepinephrine. Cortisol appears to be the reason for this lack of neurogenesis.
Cognitive models of depression began emerging in the 1950s with the work of Beck. Cognitive etiologies focus on cognitive factors (thoughts and beliefs) in explaining depression. Empirical studies have shown that people with depression have negative thoughts and that they display learned helplessness/hopelessness.
A cluster of negative thoughts and beliefs cause depression
Beck argues that people with depression have a triad of negative thoughts about themselves, the world, and the future. These negative thoughts give life events distorted meanings, which cause emotional disturbances. Negative schemas and cognitive errors also lead to depression.
Learned helplessness explains the etiology of depression
According to the theory of learned helplessness, depression occurs when a person learns that their attempts to escape negative situations make no difference. As a consequence, they become passive and will endure aversive environments even when escape is possible.
Social psychologists argue that sociocultural factors cause depression. These include socioeconomic stresses and social isolation, cultural diversity, sociopolitical discourses, and inequities. The biosocial approach combines biological make-up and sociocultural conditions.
The diathesis-stress model explains the etiology of depression
The diathesis-stress model of depression posits that depression results from an interaction between inherent vulnerability and environmental stressors. Stress may act as a trigger to activate a biological predisposition to depression, especially when individuals lack resources to cope with stress.