Reviewed by the Help Dementia Editorial Team — our editors review every article for accuracy against guidance from the National Institute on Aging, the Alzheimer’s Association, and peer-reviewed sources.
The AD8 is a brief eight-question screening tool designed to detect cognitive impairment by asking informants (usually family members) whether they’ve noticed changes in a person’s memory, problem-solving, and daily functioning over the past 10 years. However, depression can significantly muddy the results of this test because depression itself causes cognitive symptoms that mimic early dementia—a condition sometimes called pseudodementia or depression-related cognitive impairment. If someone scores poorly on the AD8, it may indicate actual cognitive decline, depression, or often both conditions occurring together, which is why depression screening must accompany cognitive assessment.
The relationship between the AD8 and depression matters because depression is common in older adults and can produce symptoms that look identical to early-stage dementia: memory lapses, difficulty concentrating, slowed thinking, and withdrawn behavior. A person experiencing moderate depression might genuinely feel like their memory has declined, and an informant might report this as a real change. The AD8 can’t distinguish between these causes on its own, so clinicians using this tool need to understand that a positive AD8 result (suggesting cognitive decline) requires follow-up evaluation specifically checking for depression.
Table of Contents
- Can Depression Cause a High AD8 Score?
- The AD8’s Limitations When Depression Is Present
- When Cognitive Decline and Depression Overlap
- How to Use the AD8 Appropriately When Depression Is a Possibility
- Misdiagnosis Risks: When Depression Is Missed
- Other Screening Tools That Work Alongside the AD8
- Comprehensive Evaluation and Moving Forward
- Conclusion
Can Depression Cause a High AD8 Score?
Yes, depression can produce a positive ad8 screening result even when significant cognitive impairment isn’t present. Depression affects attention, concentration, and motivation—a depressed person may struggle to remember conversations or complete familiar tasks not because of dementia but because depression has reduced their mental energy and engagement. A family member noticing these changes may correctly report them on the AD8, yet the underlying cause is depression rather than neurodegeneration. This is particularly common in older adults who have recently experienced loss, significant life changes, or medical illness.
The challenge is that depression-related cognitive problems are reversible, while Alzheimer’s disease and other dementias typically are not. Someone with pseudodementia who receives effective depression treatment—whether through therapy, medication, or addressing underlying health issues—may see their cognitive complaints resolve or substantially improve. By contrast, someone with true cognitive decline from dementia will generally continue deteriorating despite treatment for depression. This distinction has real consequences: misidentifying depression as dementia can lead to unnecessary specialist referrals, diagnostic testing, and anxiety, while missing early dementia allows it to progress without appropriate planning and intervention.
The AD8’s Limitations When Depression Is Present
The AD8 itself has no built-in mechanism to detect or account for depression. It simply asks questions about cognitive change; it doesn’t measure mood, motivation, or emotional factors that might explain those changes. If someone is severely depressed and withdrawing from activities, they might report memory problems that improve once depression is treated. If an informant is depressed themselves, they may overestimate or misinterpret the person’s cognitive changes.
The test was designed to be quick and efficient, which means it sacrifices specificity for simplicity—it’s meant to flag people who need further evaluation, not to diagnose. Another limitation is that the AD8 relies entirely on informant reporting, meaning its accuracy depends on how well the family member knows the person and how objectively they can assess change. Someone newly bereaved or caring for a depressed relative may interpret normal forgetting as decline because they’re stressed or worried. Additionally, depression in the person being screened can make them less engaged in the assessment process itself, potentially affecting how family members characterize their functioning. A clinician using the AD8 in isolation risks misinterpreting depression-related cognitive symptoms as evidence of dementia, particularly if depression screening isn’t also performed.
When Cognitive Decline and Depression Overlap
Many older adults experience both depression and actual cognitive decline simultaneously, which complicates interpretation of any screening result. Someone in their 70s might have mild cognitive impairment from early Alzheimer’s disease and also experience depression triggered by the anxiety of noticing their memory changing. Or someone might develop both depression and progressive brain changes from vascular disease. In these cases, the AD8 may accurately identify cognitive decline, but the positive result doesn’t tell us how much of the problem is dementia and how much is depression—that distinction matters for treatment planning. For example, an 78-year-old woman might score 6 out of 8 on the AD8, indicating likely cognitive impairment.
Her family reports that over the past three years she has become more forgetful, slower to make decisions, and withdrawn from social activities. During evaluation, a depression screening might reveal significant depression symptoms that began about two years ago, coinciding with her husband’s death. She may have mild cognitive impairment that existed before the depression, and the grief-related depression has made it more noticeable and more functionally impairing. Treatment of her depression with antidepressant therapy and grief counseling might improve her cognitive function, but some genuine cognitive decline may persist. The AD8 identified that something is wrong, but additional evaluation was necessary to understand what.
How to Use the AD8 Appropriately When Depression Is a Possibility
The AD8 works best as the first step in evaluation, not as a definitive diagnosis. If someone screens positive on the AD8, the next steps should include depression screening using a validated tool like the Geriatric Depression Scale or PHQ-9, along with detailed cognitive testing, neuropsychological evaluation if indicated, and medical workup to rule out other causes of cognitive complaints (thyroid disease, medication effects, vitamin deficiencies, sleep disorders). A primary care physician or geriatrician should obtain a thorough history of when cognitive changes began, whether they’re stable or progressive, and what other symptoms have developed alongside them. The practical approach is to administer the AD8 alongside depression screening, not instead of it.
If someone scores high on both the AD8 and a depression screen, depression treatment becomes a critical first step. Starting an antidepressant, engaging in therapy, or addressing a major life stressor might substantially improve cognitive symptoms. If cognitive symptoms improve with depression treatment, that supports the pseudodementia diagnosis. If they persist or continue worsening despite treatment of depression, further evaluation for dementia is warranted. Using both tools together provides much better clinical information than the AD8 alone.
Misdiagnosis Risks: When Depression Is Missed
One significant risk is that clinicians focus solely on the positive AD8 result and pursue dementia workup without adequately screening for depression. An older person might undergo expensive and unnecessary brain imaging, genetic testing for Alzheimer’s disease, and multiple specialist visits while their underlying depression remains untreated. During this period, the depression worsens, potentially leading to social isolation, poor self-care, medication non-adherence, and even suicide risk. The person and their family also experience anxiety and uncertainty while awaiting test results, when what they actually need is depression treatment.
The opposite risk also exists: a clinician might recognize depression and treat it effectively, assuming cognitive symptoms will resolve, only to discover that the person has underlying dementia that becomes more apparent once depression improves. For instance, antidepressant treatment might restore someone’s motivation and engagement, revealing that their memory impairment was more severe than the depression alone could explain. This delayed recognition of dementia can mean the person misses the window for early intervention, disease-modifying treatments (if available), and importantly, time to make advance care planning decisions while still cognitively intact. The AD8 serves its purpose best when it prompts comprehensive evaluation rather than a single diagnostic pathway.
Other Screening Tools That Work Alongside the AD8
To create a more complete picture, clinicians often combine the AD8 with the Geriatric Depression Scale (GDS), a 15-item tool specifically designed to screen for depression in older adults, or the shorter PHQ-9. These depression screens can help determine whether depressive symptoms are present and how severe they are. Other cognitive screening tools like the Montreal Cognitive Assessment (MoCA) or Mini-Cog provide more detailed cognitive information than the AD8, helping to clarify the nature and extent of any cognitive problems. Together, these tools give a much clearer sense of whether someone’s problems stem primarily from depression, primarily from cognitive decline, or from both.
The combination approach is particularly valuable because each tool answers a different question. The AD8 asks “Has cognition changed?” The depression screen asks “Is depression present?” Cognitive screening tests ask “What is the current level of cognitive function across different domains?” When all three are administered, clinicians can begin to piece together the real picture. A person might have a positive AD8 with high depression scores and relatively intact cognitive testing, suggesting pseudodementia. Another might have a positive AD8, low depression scores, and specific cognitive deficits on testing, suggesting true dementia. This layered approach prevents both over-diagnosis of dementia in depressed individuals and under-recognition of dementia in those who also have depression.
Comprehensive Evaluation and Moving Forward
If someone screens positive on the AD8, the next essential step is a comprehensive evaluation by a qualified healthcare provider—ideally a primary care physician, geriatrician, or neurologist, depending on availability. This evaluation should include a detailed history of cognitive changes (when they started, how they’ve progressed, whether they fluctuate), a depression screening, a physical exam, basic laboratory work (including thyroid function, vitamin B12 level, and metabolic panel), and detailed cognitive testing if initial screening suggests impairment. Depending on the clinical picture, brain imaging or neuropsychological evaluation might be appropriate.
The AD8’s value lies in its efficiency as a screening tool that identifies people at risk for cognitive decline. Rather than trying to determine causation from the AD8 result alone, view it as an invitation to look deeper. With depression screening, broader cognitive assessment, and a thorough history, clinicians can usually distinguish between depression, early dementia, and the combination of both. This comprehensive approach ensures that people with pseudodementia receive appropriate mental health treatment rather than unnecessary dementia workup, while those with actual cognitive decline don’t have their dementia missed or delayed in diagnosis.
Conclusion
The AD8 test is a useful screening tool for cognitive change, but it cannot distinguish between cognitive decline due to dementia and cognitive symptoms caused by depression. Depression can produce a positive AD8 result by impairing memory, concentration, and motivation, and understanding this relationship is essential for anyone using this screening tool. A positive AD8 should always prompt depression screening and broader evaluation, not immediate assumptions about dementia.
If you or someone you care for screens positive on the AD8, ask your healthcare provider whether depression screening has been performed as part of the evaluation. Ensure that any cognitive workup includes assessment for depression, medication effects, medical conditions, and other reversible causes of cognitive symptoms. Early identification and treatment of depression can dramatically improve quality of life and cognitive function, while comprehensive evaluation ensures that any underlying dementia is not missed. The goal is accurate understanding of what’s causing cognitive changes so that appropriate, effective treatment can begin.
