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Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE)
Please visit this website for more information about the instrument: Informant Questionnaire on Cognitive Decline in the Elderly
Supplemental: Mitochondrial Disease (Mito) and Stroke
Short Description of Instrument
Purpose: The short form IQCODE is a subjective rating scale that captures informant ratings of change in cognitive function from premorbid function.
Overview: 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.
Time: The assessment takes approximately 10-15 minutes.
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.
Comments/Special Instructions
Information from the IQCODE and the Mini-Mental State Examination can be combined in the DemeGraph to aid in assessing for dementia.
The authors of the instrument provide these guidelines for users:
  1. The 16-item Short IQCODE is the preferred version in English. Similarly, in other languages, short versions appear to be as valid as the full questionnaire.
  2. The IQCODE is a good choice of primary screening instrument where a patient has a language or culture other than the dominant one, has a very low level of education or has previous cognitive impairment.
  3. For other patients, the IQCODE is best used in harness with a cognitive screening test like the MMSE. If both the IQCODE and the MMSE are given to all patients, they can be combined graphically using the Demograph or, alternatively, patients who score below cut-off on either test should be investigated more thoroughly.
  4. In clinical situations, a screening cut-off of 3.44+ on the Short IQCODE is a reasonable compromise for balancing sensitivity and specificity

Scoring and Psychometric Properties
Scoring: 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 participant is rated on average as "no change", 4 "a bit worse", 5 "much worse".
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. Associations with premorbid educational attainment appear to be negligible.
Key References:

Jorm, A. F., Scott, R., Cullen, J. S. and Mackinnon, A. J. (1991). Performance of the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) as a screening test for dementia. Psychological Medicine, 21, 785-790.
Jorm AF. A short form of the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE): development and cross-validation. Psychol Med. 1994 Feb;24(1):145-53. Erratum in: Psychol Med 1995 Mar;25(2):437.
Jorm AF. The Informant Questionnaire on cognitive decline in the elderly (IQCODE): a review. Int Psychogeriatr. 2004 Sep;16(3):275-93.
Jorm A. The Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE): a review. International Psychogeriatrics. 2004;16:1-19.

Additional References:

de Jonghe, J. F. M. (1997). Differentiating between demented and psychiatric patients with the Dutch version of the IQCODE. International Journal of Geriatric Psychiatry, 12, 462-65.
de Jonghe, J. F., Schmand, B., Ooms, M. E. and Ribbe, M. W. (1997). Abbreviated form of the Informant Questionnaire on Cognitive Decline in the Elderly. Tijdschrift voor Gerontologie en Geriatrie, 28, 224-29.
Fuh, J. L., et al. (1995). The Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) as a screening tool for dementia for a predominantly illiterate Chinese population. Neurology, 45, 92-6.
Isella, V., Villa, M. L., Frattola, L. and Appollonio, I. (2002). Screening cognitive decline in dementia: preliminary data on the Italian version of the IQCODE. Neurological Sciences, 23, S79-S80.
Document last updated March 2024