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Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE)
Supplemental: Mitochondrial Disease (Mito) and Stroke
Short Description of Instrument
The short form IQCODE is a subjective rating scale that captures informant ratings of change in cognitive function from premorbid function.1
The questionnaire is designed to assess cognitive decline and dementia in the elderly. It is filled out by a relative or friend who has known the elderly person for ten years or more.1
The assessment takes approximately 10-15 minutes.
The score for each question is added together and then divided by the number of questions. For the Long IQCODE, divide by 26; for the Short IQCODE, divide by 16. Scores range from 1 to 5. A score of 3 means that the subject is rated on average as “no change”, 4 “a bit worse”, 5 “much worse”.1
Psychometric Properties
The questionnaire has high reliability and measures a single general factor of cognitive decline. It validly reflects past cognitive decline, performs at least as well at screening as conventional cognitive screening tests, predicts incident dementia, and correlates with a wide range of cognitive tests.2
Other Important Notes
The IQCODE is relatively unaffected by education and pre-morbid ability or by proficiency in the culture's dominant language. It is affected by informant characteristics such as depression and anxiety in the informant and the quality of the relationship between the informant and the subject.1
1).  Jorm, A. (1994). A short form of the informant questionnaire on cognitive decline in the elderly (IQCODE): Development and cross-validation. Psychol Med, 24, 145-153.
2). Jorm A (2004). The Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE): a review. International Psychogeriatrics, 16, 1-19.
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