Psychiatry: Mood, Anxiety, Psychosis, and Substance Use in Older Adults
Core concepts
Late-life depression is common and often presents atypically: somatic complaints, anhedonia, apathy, cognitive slowing, or irritability rather than stated sadness. Depression is a risk factor for suicide, especially in older men, and is associated with worse outcomes in comorbid medical illness. Know the diagnostic criteria for major depressive disorder and the role of screening tools (PHQ-9, Geriatric Depression Scale). Bipolar disorder in late life may be new-onset and warrants evaluation for secondary causes (stroke, medication, endocrine).
Anxiety, psychosis, and substance use
Anxiety disorders persist into late life and often co-occur with depression and medical illness. Late-onset psychosis (after age 40-50) requires workup for delirium, medication effects, and neurological or metabolic causes before a primary psychotic diagnosis. Substance use is underrecognized: alcohol use disorder and prescription misuse (benzodiazepines, opioids) are common; screen with validated tools and watch for withdrawal risk.
Treatment and traps
SSRIs are first-line for depression and anxiety; start low, go slow, and monitor for hyponatremia (especially with thiazides), falls, QT effects (citalopram dose limits), and drug interactions (CYP2D6, CYP2C19). Avoid tricyclics when possible due to anticholinergic and cardiac effects. Traps: attributing depression to normal aging; missing suicide risk; overlooking drug interactions and anticholinergic burden; mislabeling delirium as psychosis. Always screen for bipolarity before starting an antidepressant.
Rule of thumb: in late life, new symptoms warrant a cause, and new-onset psychosis after midlife is secondary until proven otherwise.