Family members can make dementia assessment more accurate by describing changes they see in daily life. An informant questionnaire is a structured set of questions a clinician uses to gather those observations from someone who knows the person well. Your account can reveal difficulties that may not appear during a short office visit, such as repeated medication mistakes, unsafe financial decisions, getting lost on familiar routes, or a change in judgment. It adds context to—not a replacement for—the person's own account and clinical evaluation.
Medical information disclaimer: This article is for general educational purposes only and does not provide medical advice, diagnosis, or treatment. Always consult a physician or other qualified health professional about symptoms, medications, tests, or treatment decisions.
Table of Contents
- What a family member can report
- Why timing and patterns matter
- Common questionnaires and what they ask
- What a score can—and cannot—tell you
- How to prepare for a useful conversation
What a family member can report
Useful observations are specific, dated, and tied to real situations. The Centers for Medicare & Medicaid Services identifies changes in memory, judgment, decision-making, medication adherence, and everyday errors as evidence that may suggest cognitive impairment.
In Medicare's detailed cognitive-assessment service, an independent historian can be a spouse, parent, guardian, or another person who can provide information the patient may not give fully or reliably. This history can help fill gaps without treating the family member as the decision-maker. Bring examples such as:.
- "She paid the same utility bill twice this month."
- "He began missing doses after years of managing his pills independently."
- "She asks the same question several times during one conversation."
- "He has become confused about the route to a familiar grocery store."
Why timing and patterns matter
A questionnaire works best when it captures change from the person's usual abilities. The key question is not whether someone occasionally forgets a name, but whether memory, reasoning, orientation, or daily functioning has noticeably changed. Family informants can help establish when symptoms began, how often they occur, whether they are worsening, and how thinking or behavior has changed, according to the Alzheimer's Association's diagnostic-testing guidance.
A short timeline can make that information easier for a clinician to use. Before an appointment, note the first change you noticed, several recent examples, and whether problems happen in one setting or across several. Separate what you observed directly from what others told you.
Common questionnaires and what they ask
The AD8 is an eight-question informant interview that asks about changes in memory, orientation, judgment, and function. In its original validation, endorsing two items had 74% sensitivity and 86% specificity for very mild dementia, meaning it identified many affected people while still producing some incorrect positive results. The original *Neurology* study describes those findings. Other options include the General Practitioner Assessment of Cognition (GPCOG) and the Short IQCODE.
The Alzheimer's Association's cognitive-assessment resources list these as tools family members and close friends can complete. IQCODE focuses on cognitive and functional change over time. A Cochrane review found that the 16-item version had similar accuracy to the 26-item version, which can reduce the burden on the person completing it. The Cochrane review supports using the shorter version when that is the tool a clinician selects.
What a score can—and cannot—tell you
A concerning questionnaire score is a reason to continue assessment, not a diagnosis of dementia. Brief tools help identify people who may need a fuller evaluation or referral; they do not determine the cause of memory or thinking changes. This distinction matters because a score can be affected by the informant's knowledge of the person, the examples remembered, and the way questions are understood. The Cochrane review concluded that IQCODE used alone in community settings would create both false-positive labels and missed dementia cases.
Its findings support using informant answers as one part of a broader clinical assessment. Routine screening is also different from responding to a noticed problem. The U.S. Preventive Services Task Force found insufficient evidence to recommend for or against routine cognitive-impairment screening in asymptomatic, community-dwelling adults age 65 or older; that statement does not apply when a patient, family member, or clinician has observed symptoms. The USPSTF recommendation makes that distinction.
How to prepare for a useful conversation
Ask the person, when possible, how they would like you involved in the visit. Then offer factual observations calmly and avoid labels such as "dementia" when you are describing events. A practical approach is to: The most useful contribution is a clear picture of what has changed, when it changed, and how it affects ordinary life.
- Bring a one-page timeline of changes and examples.
- Note which tasks the person still manages independently.
- Include changes in mood, behavior, judgment, or routine as well as memory.
- Tell the clinician whether the changes are stable, intermittent, or getting worse.
- Complete any questionnaire based on usual functioning, not one unusually difficult day.
