Most screening tests for dementia involve a brief list of questions to directly assess cognitive functioning, such as the MMSE. A disadvantage of such tests is that they are affected by the persons level of education, familiarity with the dominant language and culture in their country, and level of intelligence before the onset of dementia. Because of this, cognitive screening tests can falsely indicate dementia in people with lower education, culturally and linguistically diverse backgrounds, and lower intelligence. The IQCODE attempts to overcome this problem by assessing change from earlier in life, rather than the persons current level of functioning. It does this by making use of the informants knowledge of both the persons earlier and current cognitive functioning. The Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) is a questionnaire that can be filled out by a relative or carer (the informant) of an older person to determine whether that person has declined in cognitive functioning. The IQCODE is often used as a screening test for dementia.
IQCODE is especially useful in cases where, for different reasons, a meaningful formal cognitive assessment cannot be performed. It also gives the relative an opportunity to say what they feel. IQCODE has been found to have similar specificity and sensitivity to the MMSE.
To score the IQCODE, add up the score for each question and divide by the number of questions (for the short IQCODE, divide by 16). A cut-off point of 3.31/3.38 achieves a balance of sensitivity and specificity.
Jorm, A. F. (1994). A short form of the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE): Development and cross-validation. Psychological Medicine, 24, 145-153