Psychiatric Medications in Older Adults: What Changes and What to Watch For

Pharmacokinetics — what the body does to a drug — changes substantially and predictably with age. The four major changes:

• Reduced renal clearance: Kidney function declines roughly 1% per year after age 40. Many psychiatric medications (lithium, gabapentin, some antipsychotics) are cleared primarily by the kidneys. As clearance slows, drug accumulates — meaning the same dose produces higher blood levels and longer exposure in a 70-year-old than in a 40-year-old.
• Reduced hepatic metabolism: Liver size, blood flow, and CYP450 enzyme activity all decline with age. The liver is responsible for metabolizing most psychiatric medications, including SSRIs, TCAs, benzodiazepines, and antipsychotics. Reduced hepatic metabolism means slower breakdown, longer half-lives, and higher plasma concentrations at standard doses.
• Lower albumin and increased free drug fraction: Many psychiatric medications are highly protein-bound — they travel through the bloodstream attached to albumin. Older adults typically have lower albumin levels (from decreased synthesis and dietary changes), which means a greater fraction of the drug circulates in its active, unbound form. More free drug means stronger effect at the same total dose.
• Increased fat-to-muscle ratio and volume of distribution: Lipophilic (fat-soluble) drugs — including many benzodiazepines and antipsychotics — distribute more widely in older adults who have proportionally more adipose tissue. This extends half-life and can cause unexpected accumulation over time.

“Start low, go slow” is the foundational clinical principle for psychiatric prescribing in older adults. It means:

• Begin at approximately half the standard adult starting dose (sometimes less for very frail or medically complex patients)
• Titrate upward more slowly than in younger adults — giving more time between dose increases to allow the body to equilibrate
• Set the target dose based on response and tolerability, not on what worked for a younger patient with the same diagnosis

This principle is not about being timid with treatment — it is about recognizing that the therapeutic window narrows with age. The dose that is effective may be closer to the dose that causes adverse effects. Moving carefully through that range reduces the risk of falls, cognitive impairment, cardiac events, and other serious consequences.

Critically, “start low, go slow” does not mean “stay low forever.” Under-treating psychiatric illness in older adults — particularly depression and anxiety — carries its own serious risks, including functional decline, cognitive worsening, and increased mortality. The goal is appropriate dosing reached carefully, not permanent under-treatment.

The average older adult in the United States takes 5 or more prescription medications. Many take 10 or more. This polypharmacy reality creates several overlapping risks that are directly relevant to psychiatric medications:

CYP450 Drug Interactions

Most psychiatric medications are substrates or inhibitors of CYP450 liver enzymes — the same enzymes that process cardiovascular medications, anticoagulants, pain medications, and antibiotics. Fluoxetine and paroxetine are potent CYP2D6 inhibitors that can dramatically raise blood levels of beta-blockers and certain antiarrhythmics. Fluvoxamine inhibits CYP1A2 and 3A4, raising levels of warfarin, theophylline, and many other drugs. In an older adult on a complex medical regimen, adding or changing a psychiatric medication requires a systematic interaction check.

Anticholinergic Burden

Many medications — including older antidepressants, first-generation antihistamines (Benadryl), bladder medications (oxybutynin), and some antipsychotics — have anticholinergic properties. Individually, these effects may be tolerable. In combination, they accumulate. High anticholinergic burden in older adults is associated with cognitive impairment, constipation, urinary retention, dry mouth, blurred vision, and increased fall risk. The Anticholinergic Cognitive Burden (ACB) scale helps quantify this cumulative load.

QTc Prolongation

Multiple psychiatric medications (citalopram at higher doses, haloperidol, quetiapine, ziprasidone) can prolong the QTc interval on EKG — a marker of cardiac arrhythmia risk. When combined with other QTc-prolonging medications common in older adults (certain antibiotics, antifungals, antiemetics, and cardiac medications), the cumulative risk increases. Older adults with cardiac history or on complex cardiac regimens need an EKG before and during treatment with QTc-prolonging psychiatric medications.

The American Geriatrics Society (AGS) Beers Criteria is an evidence-based list of medications that should be used with caution or avoided in older adults (generally defined as 65+). Updated regularly, it is a reference tool for prescribers, pharmacists, and patients alike. The psychiatric medication categories explicitly flagged:

• Benzodiazepines (all types): Explicitly listed as potentially inappropriate regardless of duration. In older adults, benzodiazepines are associated with increased fall risk, hip fractures, cognitive impairment, motor vehicle accidents, and paradoxical agitation. Older adults metabolize them slowly (especially long-acting ones like diazepam and clonazepam), leading to accumulation. The AGS recommends avoiding in older adults with insomnia, agitation, or delirium unless no safer alternative exists.
• Tricyclic antidepressants (TCAs): Amitriptyline, doxepin (at doses above 6 mg), imipramine — highly anticholinergic, sedating, and cardiotoxic at older-adult pharmacokinetic profiles. Associated with orthostatic hypotension, falls, and cognitive impairment. SSRIs and SNRIs are strongly preferred for late-life depression.
• First-generation (typical) antipsychotics: Haloperidol, chlorpromazine, and other typical antipsychotics carry higher risk of extrapyramidal side effects (rigidity, dystonia, akathisia) and tardive dyskinesia in older adults compared to second-generation (atypical) antipsychotics. When antipsychotics are needed, second-generation options with lower EPS profiles are generally preferred.
• Anticholinergic antihistamines: Diphenhydramine (Benadryl) — widely available over the counter and often used as a sleep aid — is explicitly flagged. It is highly anticholinergic, causes daytime sedation, confusion, and constipation, and is associated with falls and cognitive effects disproportionate to its modest sedating benefit.

One of the most clinically challenging questions in geriatric psychiatry is distinguishing medication-induced cognitive changes from natural dementia progression. Both can present as worsening memory, confusion, and disorientation — but they have very different implications for management.

Signs that cognitive changes may be medication-related:

• Acute or subacute onset — changes appearing over days to weeks, not months to years
• Temporal relationship to a medication change (addition, dose increase, or switching to a higher-anticholinergic option)
• Fluctuating course — cognitive impairment that varies by time of day, often correlating with peak medication levels (typically 1–3 hours post-dose)
• Disproportionate sedation relative to therapeutic effect
• Improvement after dose reduction, timing adjustment, or medication change

The most implicated drug classes: benzodiazepines, anticholinergics (including diphenhydramine and many older antidepressants), antipsychotics at higher doses, and opioids. When cognitive concerns emerge, a systematic medication review — not just a dementia workup — should be the first step.

Falls in older adults are not minor events. Hip fractures in adults 65+ carry a 20–30% one-year mortality rate and often mark a permanent inflection point in functional independence. Psychiatric medications contribute to fall risk through two main mechanisms:

• Sedation and psychomotor slowing: Benzodiazepines, sedating antidepressants (mirtazapine, TCAs), and antipsychotics impair reaction time, balance, and coordination — all of which matter for fall prevention. The impairment may not be subjectively obvious: an older adult may feel only mildly tired but have significantly slowed protective reflexes.
• Orthostatic hypotension: Many psychiatric medications cause the blood pressure to drop when moving from lying to sitting or standing (orthostatic hypotension). In older adults with reduced cardiovascular reflexes, this drop is both more pronounced and slower to correct, causing the lightheadedness or syncope that precedes many falls. The most implicated agents: TCAs, low-potency antipsychotics (quetiapine, clozapine), MAOIs, and alpha-1-blocking antidepressants (trazodone, mirtazapine).

Practical implications: if a fall occurs in a patient on psychiatric medications, the medication regimen should be reviewed as part of the fall investigation — not only the patient's physical condition. Dose timing, dose level, medication combinations, and standing blood pressure measurements are all clinically relevant.

Depression is estimated to affect 15–20% of older adults in community settings and 25–50% in medically ill or institutionalized populations — and is chronically underdiagnosed and undertreated in this age group. Several factors contribute to this gap:

• Depression in older adults often presents atypically — less prominent sadness, more somatic complaints (fatigue, pain, gastrointestinal symptoms), cognitive slowing, and social withdrawal
• Both clinicians and patients may incorrectly attribute symptoms to “normal aging” or medical illness
• Generational stigma about mental health reduces disclosure and help-seeking
• Medical illness complicates the diagnostic picture — fatigue from chemotherapy looks like depression; insomnia from chronic pain looks like depression

Untreated late-life depression is not benign. It is associated with accelerated cognitive decline, increased medical morbidity, longer hospital stays, reduced adherence to medical treatment, and significantly elevated suicide risk. The suicide rate in older white men is the highest of any demographic group in the United States.

SSRIs remain the first-line pharmacotherapy for late-life depression — particularly sertraline and escitalopram, which have cleaner interaction profiles and lower anticholinergic burden than older antidepressants. Doses should be started low and titrated carefully, but adequate dosing is essential — under-treating to minimize side effects is not a safe option.

Since 2005, the FDA has required a black box warning on all atypical antipsychotics used in older adults with dementia-related behavioral disturbances. The warning indicates an approximately 1.6–1.7x increased risk of death (primarily from cardiovascular events and infections) compared to placebo in this population. This is not a theoretical risk — it reflects real, replicated clinical trial data.

Despite this, antipsychotics are sometimes still used in dementia patients — and not always inappropriately. The clinical reality is that dementia-related psychosis (delusions, hallucinations), severe agitation, or aggression that poses safety risks to the patient or caregivers may not respond adequately to non-pharmacological interventions alone. When the behavioral disturbance is dangerous and alternatives have failed, the risk-benefit calculation may still favor a carefully chosen, carefully dosed antipsychotic with close monitoring.

What the evidence says:

• Non-pharmacological interventions (person-centered care, environmental modification, caregiver training) should always be attempted first for behavioral and psychological symptoms of dementia (BPSD)
• When medication is used, the lowest effective dose for the shortest necessary duration is the standard of care
• Quetiapine has the least EPS risk among atypical antipsychotics but the evidence for it in dementia is modest; risperidone has the most RCT evidence for BPSD but higher stroke risk
• Regular reassessment for continued need — and gradual discontinuation when possible — is part of appropriate management

Many older adults are on psychiatric medications that were prescribed years or decades ago and have never been systematically reviewed. Initiating that conversation with your prescriber is appropriate and important:

What to Bring to the Appointment

• A complete medication list — including over-the-counter medications, vitamins, supplements, and herbal products (many interact with psychiatric medications in clinically significant ways)
• A list of all prescribers involved in your care, with their specialties
• Any recent changes in how you are feeling — memory, energy, mood, sleep, falls, balance, dizziness when standing
• Recent lab results, particularly kidney function (creatinine, eGFR), electrolytes, and liver function

Questions to Ask

• “Are any of my medications on the Beers Criteria for older adults? If so, what is the risk-benefit rationale for continuing them?”
• “Given that I am now [age], should any of my doses be adjusted based on how medications are processed differently at this age?”
• “Do any of my medications interact with each other, especially my psychiatric medications and my heart/blood pressure medications?”
• “I've noticed [specific change — more forgetful, unsteady on my feet, dizzy when I stand up]. Could any of my medications be contributing?”
• “Is there a psychiatric pharmacist or geriatric psychiatrist who should be involved in my care?”

One of the highest-risk situations in geriatric medication management is a lack of coordination between psychiatric and primary care providers. The psychiatrist prescribes based on mental health needs; the cardiologist manages heart medications; the primary care provider handles everything else. None of them has the full picture — and drug interactions occur at the intersections.

Practical coordination strategies:

• Designate one prescriber — often the primary care provider or a geriatrician — as the coordinator who maintains the complete medication list and reviews it at every visit
• Request that all prescribers have access to the same medication list via a shared health record or patient-maintained document
• Use a pharmacy consistently — using a single pharmacy allows the pharmacist to run interaction checks across all prescribers
• Ask for a formal medication reconciliation review at each transition of care (hospital discharge, new specialist, annual wellness visit)
• Consider asking for a comprehensive geriatric assessment if managing 5 or more medications with multiple prescribers — this is a specialized visit focused specifically on medication optimization, function, and fall risk