Overview of Depression Causes

There is no single cause of depression.

Its origin can vary from person to person and it generally emerges from a combination of factors, including biological, personality, environmental and emotional maturity factors (e.g., effective coping skills and level of psychological resilience).

Common causes of depression include neurochemical imbalances, altered brain structures, psychosocial stressors, and negative thought patterns.

Neurochemical imbalances.

The brain is a pharmacy, and changes in brain chemistry influence our mood and thought processes. Depression may be caused by fluctuations in the levels of brain chemicals such as neurotransmitters and neurohormones, including: serotonin, dopamine, norepinephrine, epinephrine, GABA (Gamma-aminobutyric acid), and cortisol. These brain chemicals influence every aspect of our being, including mood, motivation, energy, attention, sense of enjoyment and well-being. Here’s how… What Depression Looks Like in the Brain.

Altered brain structures.

Chronic depression, over time, can produce marked changes in critical brain structures such as the amygdala, hippocampus and hypothalamus, and in some cases, structural dysfunction can predispose people to depression. The amygdala and the hippocampus work in tandem to generate emotions, attach emotions to memories, and store and index those memories. The hypothalamus plays a critical role in controlling the autonomic nervous system, receiving input from noradrenergic (involving noradrenaline or norepinephrine) and serotonergic (involving serotonin) neural pathways that influence functions such as appetite, energy, drive, motivation and overall sense of well-being. For more, see What Depression Looks Like in the Brain.

Psychosocial stressors.

Clinical depression can be triggered by one or more severe psychosocial stressors. Psychosocial stressors are stress-triggering events that can impact our social and psychological behavior, such as loss, trauma, relationship problems and any other stressor or life change that we find challenging to cope with. For more, see Psychosocial Stressors: Loss, Stress, Trama, & Troubled Relationships.

Negative thought patterns and negative outlook.

Emotional well-being is associated with a positive and optimistic — yet realistic — outlook on life.  Prolonged negative thinking can create an endless negative feedback loop that colors our entire outlook on life and spirals into depression. Negative thought patterns can deplete our inner reservoir of self-esteem and resilience, making it more difficult to cope with stressors. For more, see Negative Thinking, Negative Outlook on Life.

Depression is linked to immunity.

Severe, chronic stress depresses immune function, and immune dysfunction diminishes the body’s ability to fight any disease or disorder, including depression. Research shows that people with depression tend to have higher levels of immune system inflammation or over-activated immune systems, even when they’re not fighting infections. And so many of the genetic variants that have been linked to depression have also been found to affect immune system function. Is depression embedded in the genome? For more, see Is Depression a Byproduct of Our Immune Systems.

Depression is associated with medical conditions and co-occurs with other psychological disorders.

For more, see Depression Associated with Medical Conditions and Psychological Disorders.