Chapter 55: Geriatric Psychiatry

Geriatric psychiatry addresses the unique mental health needs of adults aged 65 and older, integrating biological, psychological, and social perspectives to understand how aging affects psychiatric presentation and treatment. The chapter establishes the epidemiological context by documenting the rapid growth of the older adult population and increasing life expectancy, which create expanding demands for specialized psychiatric services. A fundamental distinction emerges between normative cognitive aging and pathological decline, as students must learn to recognize psychiatric disorders rather than attributing all symptoms to aging itself. The prevalence of late-life psychiatric conditions is substantial, with approximately one in five older adults experiencing diagnosable disorders including depression, anxiety, psychosis, and substance use problems, yet many cases remain underdiagnosed due to stigma, limited access to geriatric specialists, and cohort-specific help-seeking behaviors. Neurobiological mechanisms underlying aging include changes in neurotransmitter systems, alterations in brain structure and function, and paradoxical preservation of neuroplasticity even in advanced age, demonstrating that older adults retain capacity for neural adaptation and recovery. Psychosocial dimensions encompass grief and loss, bereavement, social isolation, caregiver stress, and protective factors such as social connection, spiritual meaning, and sense of purpose that buffer against mental illness. Clinical management requires age-appropriate pharmacology accounting for altered drug metabolism, increased sensitivity to side effects, and complex polypharmacy, combined with evidence-based psychotherapies including cognitive-behavioral therapy, reminiscence work, and interpersonal approaches. The chapter emphasizes ethical complexities surrounding informed consent, decisional capacity, advance directives, and end-of-life care planning that clinicians must navigate with older patients and families. Throughout, the field reframes aging not solely as vulnerability but as encompassing wisdom, psychological resilience, and continued potential for personal growth and meaning-making, positioning geriatric psychiatry as essential to comprehensive mental healthcare in an aging society.