AD8: Eight-item Informant Interview to Differentiate Aging and Dementia

What this assessment is

The AD8 is an eight-item informant screen for change in memory, thinking, judgment, and everyday function.

Its full name is the Eight-item Informant Interview to Differentiate Aging and Dementia.

The informant reports whether each ability has changed from the person's previous level. The focus is decline, not performance on a task given that day.

Observed change is the focus.

The AD8 can identify a reason for further cognitive assessment. It does not diagnose dementia.

Who it was designed for

The standard AD8 is completed by someone who knows the person well. This may be a spouse, adult child, friend, or regular caregiver.

The informant needs enough contact to judge whether the person's abilities have changed. A distant relative or new caregiver may not have the history needed for a reliable answer.

Who answers matters.

Contact shapes accuracy.

The measure is often used with older adults in memory, primary-care, community, and research settings. Later studies have examined self-report use, but that is not the same as the original informant format.

Name who completed the form and how they know the person.

How it is administered

The informant answers eight questions about changes in the person's cognitive and functional abilities.

The Washington University AD8 guide describes a typical completion time of about three minutes.

The interviewer can clarify what period and person the question concerns. They should not persuade the informant to choose a particular answer.

Use all eight responses for the standard total. If an answer is missing or uncertain, follow the official scoring instructions rather than treating it as no change.

What it measures

The AD8 asks about decline across memory, orientation, judgment, and daily function.

This makes it different from a direct cognitive test. The person being assessed does not solve memory, drawing, or attention tasks. Instead, another person reports change observed in daily life.

The Short IQCODE is also an informant measure of cognitive change, but it uses 16 comparisons and an average score. The MoCA 8.1 directly samples cognitive performance.

These approaches can complement each other. They do not produce interchangeable scores.

How scoring works

Each endorsed change contributes one point. Add the eight responses for a total from 0 to 8.

Higher totals mean that the informant reported more areas of change.

Change drives scoring.

The standard interpretation uses one main boundary:

• 0 to 1: within the published normal range
• 2 to 8: positive screen for possible cognitive impairment

The total is a count of reported changes. It is not a severity scale with eight equal clinical steps.

Do not calculate a standard score from an incomplete form unless the current official protocol gives a rule for that situation.

How to interpret an AD8 score

A score of 2 or more means the informant noticed enough change to cross the AD8 screening threshold.

The number opens discussion.

It does not mean that dementia is present. It also does not identify the type, cause, or stage of any cognitive disorder.

Review a positive screen with the person's own concerns, direct cognitive testing, daily function, medicines, mood, sleep, sensory problems, medical history, and course of change.

A score of 0 or 1 lowers concern on this screen but does not rule out decline. The informant may have limited contact, may normalize gradual changes, or may not observe problems that appear in other settings.

Treat the score as one source of history.

Follow-up needs context.

What the score cannot tell you

The AD8 cannot separate Alzheimer's disease from another cause of cognitive or functional change.

Depression, delirium, stroke, medicine effects, substance use, sleep disorders, pain, sensory loss, and physical disability can affect the changes an informant notices.

Informants can disagree because no one sees every part of a person's life, and expectations, stress, memory, and relationship can shape the report.

Reports can differ.

The AD8 does not assess decision-making capacity and cannot replace a clinical evaluation.

Evidence and limitations

The original AD8 validation study developed the short interview to distinguish normal aging from cognitive change associated with dementia.

Its main strength is speed and the use of observed change from a previous level. That can reveal decline even when a person performs reasonably well during one brief appointment.

Its main limitation is the same design feature. The result depends on the informant's knowledge, memory, and judgment.

Record the respondent, setting, language, and reason for screening with the score.