Description

• Depression is a primary mood disorder characterized by a depressed mood and/or a markedly decreased interest or pleasure in normally enjoyable activities for at least 2 weeks and causing significant distress or impairment in daily functioning.
• It is not considered a part of normal aging.

Epidemiology

Prevalence rates among the elderly vary, largely depending on the specific diagnostic instruments used and their current health and/or home environment:

• 1–3% of community-dwelling elderly
• 7.5% seen in primary care clinics
• 10–21% of hospitalized elderly patients
• 12–27% of nursing-home residents

Risk Factors

• General:
  • Chronic physical health condition(s)
  • History of mental health problems
  • Death of a loved one
  • Caregiving
  • Social isolation
  • Lack/Loss of social support
  • Significant loss of independence
  • Uncontrolled pain
  • Insomnia/Sleep disturbance
• Prevalence of depression in medical illness:
  • Stroke (22–50%)
  • Cancer (18–50%)
  • Myocardial infarction (15–45%)
  • Parkinson disease (10–39%)
  • Rheumatoid arthritis (13%)
  • Diabetes mellitus (5–11%)
  • Alzheimer dementia (5–15%)
• Suicide:
  • Suicide is the 11th leading cause of death in the US for all ages.
  • Suicide rates are higher for Americans age >65 compared with the general population (∼15/100,000 people).
  • Suicide rates are highest for males aged >75 (rate 38.5/100,000).

Pathophysiology

• Significant gaps exist in the understanding of the underlying pathophysiology.
• Ongoing research has identified several possible mechanisms, including:
  • Monoamine transmission and associated transcriptional and translational activity
  • Epigenetic mechanisms and resilience factors
  • Neurotrophins, neurogenesis, neuroimmune systems, and neuroendocrine systems

Etiology

Depression appears to be a complex interaction between heritable and environmental factors.