Psychology RootsInformant Questionnaire on Cognitive Decline in the Elderly
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About Informant Questionnaire on Cognitive Decline in the Elderly
Scale Name
Informant Questionnaire on Cognitive Decline in the Elderly
Author Details
Anthony Jorm
Translation Availability
English
Background/Description
The Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE), developed by Anthony F. Jorm in 1989, is a widely used tool designed to measure changes in cognitive function over time based on informant reports. Unlike traditional cognitive assessments that rely on direct testing of the patient, the IQCODE is based on information provided by a relative, caregiver, or close associate who has observed the individual over the previous ten years.
The IQCODE assesses memory, learning, recognition, comprehension, and reasoning abilities, offering valuable insights into cognitive decline patterns. This long-term perspective helps capture the natural course of dementia, distinguishing it from temporary or situational impairments. The measure is particularly effective for individuals with limited literacy or educational barriers, as it avoids direct patient testing.
Initially designed as an interview schedule, the IQCODE evolved into a self-administered questionnaire consisting of 26 items. Each item asks the informant to rate changes in cognitive ability on a 5-point Likert scale, where 1 = much improved, 3 = no change, and 5 = much worse. Scores are averaged to provide an overall index of cognitive decline, interpreted relative to standardized cut-offs. Shortened versions of 16 items have also been validated, offering quicker administration without loss of reliability or validity.
The IQCODE has become a cornerstone in both clinical assessment and epidemiological research for dementia, often used alongside direct performance measures such as the Mini-Mental State Examination (MMSE) to enhance diagnostic accuracy.
Administration, Scoring and Interpretation
- Obtain the IQCODE from Jorm (1989) or Psychological Medicine, ensuring ethical permissions.
- Explain to informants (relatives/friends of adults 65+ with suspected cognitive issues) that the questionnaire assesses cognitive changes over 10 years, emphasizing confidentiality and voluntary participation.
- Administer the 26-item self-report scale to the informant in clinical or community settings, with items rated on a 1–5 scale based on observed changes.
- Estimated completion time is 10–15 minutes.
- Ensure a private, supportive environment; provide clear instructions and adapt for accessibility (e.g., large print, assistance for literacy) if needed.
Reliability and Validity
- Reliability: The IQCODE demonstrates strong internal consistency, with Cronbach’s alpha values typically above 0.90. Test–retest reliability is also robust, with high correlations across repeated administrations.
- Validity: The scale shows strong criterion validity, correlating well with clinical diagnoses of dementia and with performance-based cognitive tests. Cut-off scores of 3.3–3.6 have been widely used to differentiate between normal aging and pathological decline. Predictive validity studies indicate that individuals with higher scores are at greater risk of future dementia diagnosis and mortality. The tool is widely validated across different populations and cultural contexts.
Available Versions
26-Items
Reference
Jorm, A. F., & Korten, A. E. (1988). Assessment of cognitive decline in the elderly by informant interview. The British Journal of Psychiatry, 152(2), 209-213.
Jorm, A. F., & Jacomb, P. A. (1989). The Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE): socio-demographic correlates, reliability, validity and some norms. Psychological medicine, 19(4), 1015-1022.
Important Link
Scale File:
Frequently Asked Questions
Q1. What does the IQCODE measure?
It measures long-term cognitive changes over a ten-year period as observed by an informant.
Q2. Who completes the IQCODE?
A close relative, caregiver, or friend who knows the patient well completes the questionnaire.
Q3. What is the difference between the 26-item and 16-item versions?
The 26-item version is the original, while the 16-item short form is a quicker version validated for use in both clinical and research settings.
Q4. What score indicates dementia risk?
Cut-off scores typically range from 3.3 to 3.6, with higher scores suggesting greater cognitive decline.
Q5. Why is the IQCODE useful compared to direct tests like MMSE?
It avoids biases from education or literacy and captures long-term functional changes that direct cognitive tests may miss.
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