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The AD8 is a brief, informant-based screening tool designed to detect early cognitive decline, but medication mistakes can significantly skew results in both directions. If someone with early-stage dementia forgets to take their medications, family members might miss the cognitive signs during an AD8 interview because the cognitive symptoms appear worse than they actually are—or conversely, medications themselves might blur the true baseline, making mild cognitive impairment harder to detect. For example, a person taking sedating antihistamines or anticholinergic medications might perform worse on cognitive screening than their actual baseline allows, leading clinicians to overestimate dementia severity when the real culprit is medication-induced fog.
The intersection of medication use and cognitive screening is often overlooked in clinical practice, yet it’s one of the most common reasons for misdiagnosis or missed diagnosis in older adults. When families answer AD8 questions about memory, executive function, and daily functioning, they’re unknowingly reporting symptoms that may include drug-induced cognitive impairment rather than true dementia. Understanding how medications affect the AD8 results and the cognitive picture itself is critical for accurate diagnosis and appropriate care planning.
Table of Contents
- How Can Medications Impact AD8 Test Results?
- The Problem of Medication-Induced Cognitive Impairment Being Mistaken for Dementia
- Medication Non-Adherence and AD8 Screening Errors
- The Importance of Medication Review Before and During AD8 Screening
- Specific Medication Classes That Cloud AD8 Results
- The Role of Polypharmacy in Cognitive Screening Accuracy
- Moving Forward—Integrating Medication Assessment into Cognitive Screening
- Conclusion
How Can Medications Impact AD8 Test Results?
Medications affect cognition through multiple mechanisms, and when someone is screened with the ad8, these drug effects become entangled with the true underlying cognitive status. Anticholinergic medications—used for allergies, overactive bladder, and depression—directly impair memory and attention, the very domains the AD8 measures. Similarly, sedating medications like diphenhydramine, certain blood pressure drugs, and benzodiazepines slow processing speed and reduce alertness, making someone appear more cognitively impaired than baseline. A 76-year-old woman taking a first-generation antihistamine for seasonal allergies might report difficulty remembering recent conversations, which her daughter dutifully reports on the AD8, but after stopping the medication, the “memory problem” largely resolves—revealing that the drug, not dementia, was the culprit.
The AD8 specifically asks informants about changes in judgment, ability to handle finances, memory, confusion, driving safety, and use of technology. A person on multiple medications that cloud cognition will score higher on the AD8 (indicating more impairment), but that score doesn’t reflect their true cognitive baseline or their dementia risk. Polypharmacy—taking five or more medications—is particularly problematic because drug interactions and cumulative effects create a fog that mimics cognitive decline. Clinicians relying solely on AD8 scores without a detailed medication review may initiate dementia workups or treatments when the real solution is medication adjustment.
The Problem of Medication-Induced Cognitive Impairment Being Mistaken for Dementia
Medication-induced cognitive impairment is treatable and often reversible, unlike neurodegenerative dementia. This distinction is critical because it changes the entire care trajectory. However, the AD8 doesn’t differentiate between the two; it simply measures the cognitive state at a single point in time. If a person is experiencing drug-induced impairment when the AD8 is administered, the test will flag them as cognitively impaired, potentially leading to unnecessary prescriptions for dementia medications like donepezil or memantine—which add more drugs to an already cognitively taxing medication burden.
The limitation here is that the AD8 is a screening tool, not a diagnostic instrument. Its job is to identify people who might have cognitive impairment so they can receive further evaluation. But without a thorough medication review before or alongside AD8 screening, clinicians and families can miss the forest for the trees. A 78-year-old man experiencing confusion, memory difficulty, and reduced attention while taking lisinopril (for blood pressure), sertraline (for depression), and ranitidine (for reflux) might score in the impaired range on the AD8, get referred for neuropsychological testing, and receive a dementia diagnosis—when what he actually needs is a medication reconciliation. After adjusting doses or switching to less cognitively impairing alternatives, his cognition may improve substantially.
Medication Non-Adherence and AD8 Screening Errors
When someone doesn’t take their medications as prescribed, the cognitive and functional consequences can mimic dementia in the short term, creating another layer of diagnostic confusion. A person with well-controlled hypertension who skips blood pressure doses may experience dizziness, reduced cerebral perfusion, and temporary cognitive slowing—symptoms that appear on the AD8 as impairment. Meanwhile, a person with early Alzheimer’s disease who is also non-adherent with their medications may show even more pronounced cognitive symptoms than their baseline dementia alone would produce, making their impairment appear worse than it is and affecting treatment decisions.
Non-adherence is common in older adults, particularly those with early cognitive decline who struggle to remember medication schedules. The family answering the AD8 questions may attribute confusion and forgetfulness to dementia when some of it stems from medication misses. For instance, a woman with mild cognitive impairment who frequently forgets to take her metformin for diabetes might show glucose fluctuations that impair her cognition on the days she misses doses, creating an inconsistent cognitive picture that confuses both family and clinicians. The AD8 captures a snapshot, and if that snapshot occurs on a day when medications were missed, the results may be misleading.
The Importance of Medication Review Before and During AD8 Screening
Best practice dictates that any cognitive screening should begin with a thorough medication review, including over-the-counter drugs, supplements, and herbals. Comparing the list of current medications to a reference database of drugs known to impair cognition—such as anticholinergics, sedating antihistamines, opioids, and certain statins—helps clinicians and families distinguish between medication effects and true dementia. This review should include dosages, frequency, duration of use, and any recent changes, because even a dose increase of a longstanding medication can suddenly trigger cognitive impairment. The tradeoff is that thorough medication review takes time and expertise that many primary care settings don’t allocate to cognitive screening.
A quick 10-minute AD8 interview followed by referral to a specialist is faster but risks missing the medication contribution entirely. A more thorough approach involves the primary care provider or a pharmacist reviewing medications, potentially adjusting or discontinuing culprits, waiting 2-4 weeks for the cognitive effects to clear, and then repeating the AD8 or cognitive screening to establish true baseline. This takes longer but produces more accurate results and avoids unnecessary dementia diagnoses and treatments. Many families and older adults prefer this approach because it addresses a treatable problem before jumping to neurodegenerative disease diagnosis.
Specific Medication Classes That Cloud AD8 Results
Anticholinergic medications are the most notorious cognitive offenders, and they’re ubiquitous in older adult medicine. Diphenhydramine, promethazine, atropine, scopolamine, and oxybutynin directly block acetylcholine, a neurotransmitter essential for memory and attention. Someone taking a single-dose anticholinergic is already at risk for cognitive impairment; someone on multiple anticholinergics or on one anticholinergic plus other cognitive-impairing drugs is at high risk. Similarly, benzodiazepines like lorazepam and diazepam impair memory consolidation and processing speed, and even short-term use in older adults can produce cognitive effects that last weeks after discontinuation.
A warning here: older adults should generally avoid these medication classes altogether due to dementia risk, but many are prescribed them for anxiety or insomnia, creating a vicious cycle where the medication itself increases dementia-like symptoms. Opioid medications, commonly prescribed for pain, also significantly impair cognition in older adults, yet this effect is often attributed to dementia rather than the medication. Tricyclic antidepressants with anticholinergic properties, such as amitriptyline, are similarly problematic. The limitation is that sometimes these medications are medically necessary, and clinicians must weigh cognitive risk against symptom management. However, alternatives often exist—SSRI antidepressants, for example, have far less cognitive impact than tricyclics—and exploring these alternatives before administering the AD8 can yield clearer results about true baseline cognition.
The Role of Polypharmacy in Cognitive Screening Accuracy
Polypharmacy—the concurrent use of multiple medications—is exponentially more cognitively risky than single-drug use. A person on eight medications, even if none is individually problematic at standard doses, may experience significant cognitive effects from drug interactions and cumulative burden. The older adult body metabolizes drugs more slowly, leading to accumulation; drug interactions can increase blood levels of cognitive-impairing compounds; and the overall pill burden itself reduces adherence, creating medication misses that further cloud the cognitive picture.
For example, a 82-year-old man taking metoprolol for heart rate, lisinopril for blood pressure, sertraline for depression, omeprazole for reflux, atorvastatin for cholesterol, aspirin for stroke prevention, levothyroxine for thyroid, and diphenhydramine for sleep is at significant risk for cognitive impairment from the combination, even though each drug individually might be acceptable. When his family answers the AD8, they report confusion, memory problems, and reduced interest in activities—all of which could reflect true dementia, but are actually exacerbated by the medication load. A medication review focusing on deprescribing (reducing unnecessary medications) could improve his cognition substantially.
Moving Forward—Integrating Medication Assessment into Cognitive Screening
The future of cognitive screening in primary care increasingly involves pharmacist-led medication reviews integrated into dementia diagnostic pathways. Some healthcare systems now require a medication reconciliation and review before AD8 or other cognitive screening can be interpreted, treating the medication component as foundational rather than optional. This approach acknowledges that accurate cognitive assessment in older adults requires understanding both the neurological baseline and the pharmacological overlay.
As dementia awareness increases and more older adults are screened, the stakes of medication-related misdiagnosis rise. Getting the diagnosis right—distinguishing between true dementia, medication-induced impairment, and normal aging—determines whether someone receives dementia medications they may not need or misses the opportunity to address a treatable medication problem. Integration of medication review into cognitive screening protocols represents a practical, evidence-based shift toward more accurate diagnosis and safer prescribing in older adults.
Conclusion
The AD8 is a valuable screening tool, but its results must be interpreted in the context of an individual’s medication regimen. Medications can significantly impair cognition and skew AD8 results in either direction, leading to both overdiagnosis and underdiagnosis of dementia. A comprehensive approach to cognitive screening includes detailed medication review, identification of drugs known to impair cognition, consideration of dosages and interactions, and often a period of observation or adjustment before relying on screening results to guide diagnosis.
If you or a family member is undergoing AD8 screening or receiving a dementia evaluation, ensure that medication review is part of the process. Ask your healthcare provider about the cognitive side effects of current medications, whether any can be reduced or discontinued, and whether the cognitive assessment could be repeated after medication adjustments. This simple step—prioritizing medication review alongside cognitive screening—can prevent misdiagnosis, avoid unnecessary treatments, and support more accurate, individualized care for older adults.
