February 2024: Treatment-Resistant Depression in Older Adults
The issue
Treatment‑resistant depression (TRD) is common in later life and carries serious health and functional costs for older adults.
What do I need to know?
TRD usually means the illness has not improved after two adequate eight‑week trials of antidepressants from different classes. Only 35 – 73 % of older patients respond to their first drug, so many will reach this definition. Factors that make response harder include chronic medical illness, cerebrovascular disease, anxiety, dysthymia, substance misuse, and bereavement. Experts recommend measurement‑based collaborative care: regular PHQ‑9 or Geriatric Depression Scale scores, systematic checks for co‑existing conditions, and treatment adjustments until remission is sustained. The strongest medication evidence lies with augmentation (adding a second‑generation antipsychotic, lithium, or another antidepressant) rather than endless switching. When depression remains severe or complicated by suicidality, psychosis, or cognitive decline, referral for electroconvulsive therapy, ketamine/esketamine, or transcranial magnetic stimulation is advised.
Potential risk of treatment‑resistant depression
An older adult is on their first antidepressant and still has bothersome symptoms after four weeks.
Recommended Actions
Track PHQ‑9 (goal < 5) or GDS at every visit and share scores with the prescriber.
Screen for medical or psychiatric comorbidities that blunt response (pain, thyroid, anxiety, alcohol).
Confirm medication adherence and optimize dose before changing drugs.
Imminent risk of treatment‑resistant depression
Symptoms persist despite one adequate drug trial.
Recommended Actions
Discuss an augmentation plan: e.g., add low‑dose aripiprazole (2–5 mg, max 15 mg).
Alternatively switch to an SNRI (venlafaxine, duloxetine) or bupropion; choose based on energy, pain, or sleep profile.
Review fall risk and drug‑drug interactions before raising doses or adding new agents.
Confirmed treatment‑resistant depression
No remission after two or more adequate trials.
Recommended Actions
Refer to a psychiatrist for complex pharmacology or neurostimulation (ECT, TMS, intranasal esketamine).
Consider lithium augmentation (target serum 0.6 mmol/L) if kidney function allows; monitor closely.
Engage collaborative care: frequent follow‑ups, psychotherapy, safety planning for suicidal thoughts.
What can I do?
Ask the clinician, “Am I at potential, imminent, or confirmed risk of treatment resistance, and what is the step‑by‑step plan to reach remission?” Keep a symptom diary, bring medication and side‑effect lists to each visit, and involve family in monitoring mood changes and treatment adherence.
