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Printed on 7/21/2026
For informational purposes only. This is not medical advice.
IQCODE-26 is an informant questionnaire that evaluates perceived cognitive change over time in an older adult. The mean item score reflects degree of decline, with higher scores indicating greater concern.
Formula: IQCODE-26 score = mean of 26 item ratings, range 1.0-5.0.
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Select an informant who has had close, regular contact with the patient for at least 10 years and can compare current cognitive function to how the patient was 10 years ago. Family members, long-term carers, or close friends who see the patient daily or weekly are ideal informants.
The informant rates each of 26 cognitive and functional activities on a 5-point scale comparing current performance to 10 years ago: 1 = much improved, 2 = a bit improved, 3 = not much change, 4 = a bit worse, 5 = much worse. Activities include memory for recent events and conversations, orientation, use of money, managing daily tasks, and social interactions.
Sum all 26 item ratings and divide by 26 to obtain the mean score (range 1.0–5.0). A mean of 3 is neutral. Scores above 3 indicate perceived decline; the commonly used diagnostic cutoff is approximately 3.38 (sensitivity ~83%, specificity ~89%), though thresholds vary by setting and population.
General practitioners and primary care nurses
IQCODE-26 provides a low-education-bias informant perspective that complements brief cognitive tests in primary care, particularly useful in older patients where educational level may confound performance-based scores.
Anaesthesiologists and surgical teams
Identifying pre-existing cognitive decline before major surgery through an informant-based tool helps predict post-operative delirium risk and informs peri-operative monitoring requirements.
Neuropsychologists and memory clinic teams
IQCODE-26 provides collateral cognitive history in memory clinic assessments, offering longitudinal change data that standardised cross-sectional cognitive tests cannot capture.
Geriatricians and hospital medical teams
Collecting IQCODE-26 data at admission from accompanying family members establishes a cognitive baseline, helping distinguish acute confusion (delirium) from chronic impairment (dementia).
Public health researchers and epidemiologists
IQCODE-26 has been used in large-scale epidemiological studies of dementia prevalence due to its language-adaptable, informant-based format that avoids cultural and educational biases of direct cognitive tests.
The reliability of IQCODE-26 depends entirely on the informant's knowledge of the patient over time. Verify that the informant has had close, consistent contact for at least 10 years and can meaningfully compare current to past function.
Unlike the MMSE or MoCA, which penalise patients with low educational attainment, IQCODE-26 asks about change from a personal baseline. This makes it particularly valuable for assessing patients with low literacy, limited education, or non-English language backgrounds.
The standard comparison anchor is 10 years prior. If the patient has only been known to the informant for fewer years, adjust the comparison period and document this, as using a different reference period affects score interpretation.
A mean score of 3.0 technically means 'no change,' but even marginal scores above 3.0 in octogenarians carry clinical significance. Do not dismiss scores of 3.2–3.4 as normal — these represent early decline signals worth pursuing.
IQCODE-26 and MMSE/MoCA/RUDAS assess different dimensions. Concordance between a high IQCODE mean and low cognitive test performance strongly supports dementia diagnosis. Discordance (high IQCODE but normal test) may indicate rater bias or anxiety.
When administering IQCODE-26, prompt the informant with concrete examples for each item rather than abstract global assessments to improve accuracy.
The IQCODE-16 (short form) correlates closely with the 26-item version and takes approximately half the time to administer. Consider the short form for high-volume screening settings where time is limited.
Record who completed the IQCODE, their relationship to the patient, and how often they interact. A daily carer will have more accurate observations than an estranged relative who sees the patient monthly.
IQCODE long forms have longstanding validation for dementia screening support across diverse settings.
Higher IQCODE-26 means indicate greater informant-reported cognitive decline and support further evaluation.
Use when a reliable informant is available and longitudinal cognitive-change perspective is needed.
Results depend on informant accuracy, patient-contact frequency, and contextual bias.
Disclaimer: This tool is for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider with questions about your health.
April 21, 2026 · v1.0.0
Added IQCODE-26 trust metadata and initial changelog for evidence-version tracking.
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