Etiology and risk factors

Depression in older adults is a multifactorial, complex, and often underdiagnosed condition. Its etiology is associated with both biological predispositions and cumulative psychosocial factors, requiring a comprehensive and personalized approach in each case.

Genetic factors and family history

One of the main risk factors is genetic predisposition. A family history of depressive disorders significantly increases the likelihood of developing depressive symptoms in old age.

Genes related to serotonin and other neurochemicals involved in mood have been identified, suggesting a hereditary predisposition that can remain latent for years and manifest itself after triggering events.

Cumulative stressful life events

The accumulation of stressful experiences throughout life also plays a central role. Many older adults have experienced multiple losses (such as the death of loved ones, retirement, illness of themselves or their loved ones) which, although they may have been handled with resilience at the time, can have a cumulative effect that emerges in old age. This “delayed emotional exhaustion” is common and can surprise even those who were emotionally stable in earlier stages of their lives.

Neurobiological and brain changes associated with aging

At the brain level, aging causes structural and functional changes that affect emotional regulation. The volume of key regions such as the frontal lobe and hippocampus, areas involved in memory, decision-making, and mood control, decreases.

The production and reuptake of neurotransmitters such as serotonin, dopamine, and norepinephrine, which are directly involved in the onset of depressive symptoms, are also reduced.

In addition, reduced cerebral blood flow has been observed, which can contribute to so-called “vascular depression,” typical in older adults with a history of hypertension or cerebrovascular disease.

Medications and physical illnesses that trigger depressive symptoms

Polypharmacy is a common phenomenon in old age. Many drugs used to treat conditions such as hypertension, Parkinson's disease, cardiovascular disease, or chronic pain can induce depressive symptoms as a side effect.

Added to this is medical comorbidity: diseases such as hypothyroidism, diabetes, cancer, or nutritional deficiencies (such as vitamin B12 or D deficiency) can present symptoms similar to those of depression or act as triggers. A proper clinical evaluation should differentiate between primary depression and depression secondary to a medical condition.

Cognitive diathesis and individual predisposition

The cognitive diathesis model suggests that some people have negative, pessimistic, or rigid thinking styles, acquired throughout their lives, that increase their vulnerability to adverse events.

This cognitive predisposition can intensify in old age due to physical decline, loss of autonomy, or social isolation. Thus, dysfunctional coping with new or stressful situations can trigger or perpetuate a depressive episode.

In short, depression in older adults does not respond to a single cause. It is the result of the interaction between biological, psychological, and social factors, and its treatment requires a multidisciplinary approach that respects the context and life history of each person.