The Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE): a review

Background and aims: The IQCODE is widely used as a screening test for dementia, particularly where the subject is unable to undergo direct cognitive testing or for screening in populations with low levels of education and literacy. This review draws together research on the psychometric properties and validity of the IQCODE. Method: A systematic search of the literature was carried out using three databases. Results: The review shows that 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. A particular strength is that the IQCODE is relatively unaffected by education and pre-morbid ability or by proficiency in the culture's dominant language. The disadvantage of the IQCODE is that 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. Conclusions: Because the IQCODE provides information complementary to brief cognitive tests, harnessing them together can improve screening accuracy.

[1]  V. Mok,et al.  Can IQCODE detect poststroke dementia? , 2003, International journal of geriatric psychiatry.

[2]  D. Ames,et al.  A Memory Clinic at a Geriatric Hospital: A Report on 577 Patients Assessed with the CAMDEX Over 9 Years , 2003, The Australian and New Zealand journal of psychiatry.

[3]  N. Herrmann,et al.  Contribution of Informant and Patient Ratings to the Accuracy of the Mini‐Mental State Examination in Predicting Probable Alzheimer's Disease , 2003, Journal of the American Geriatrics Society.

[4]  M. Pisani,et al.  Screening for Preexisting Cognitive Impairment in Older Intensive Care Unit Patients: Use of Proxy Assessment , 2003, Journal of the American Geriatrics Society.

[5]  D. Leys,et al.  Poststroke dementia: influence of hippocampal atrophy. , 2003, Archives of neurology.

[6]  H. Christensen,et al.  Improving screening accuracy for dementia in a community sample by augmenting cognitive testing with informant report. , 2003, Journal of clinical epidemiology.

[7]  S. Sahadevan,et al.  Prevalence of cognitive impairment amongst Singapore's elderly Chinese: a community‐based study using the ECAQ and the IQCODE , 2003, International journal of geriatric psychiatry.

[8]  M. Schuurmans,et al.  The Delirium Observation Screening Scale: A Screening Instrument for Delirium , 2003, Research and Theory for Nursing Practice.

[9]  I. Appollonio,et al.  Screening cognitive decline in dementia: preliminary data on the Italian version of the IQCODE , 2002, Neurological Sciences.

[10]  D. Leys,et al.  Poststroke dementia: Incidence and relationship to prestroke cognitive decline , 2001 .

[11]  T. Davis,et al.  Dementia and its associations in type 2 diabetes mellitus: the Fremantle Diabetes Study. , 2001, Diabetes research and clinical practice.

[12]  N. Poungvarin,et al.  The IQCODE: an alternative screening test for dementia for low educated Thai elderly. , 2001, Journal of the Medical Association of Thailand = Chotmaihet thangphaet.

[13]  A. Korten,et al.  Informant ratings of cognitive decline in old age: validation against change on cognitive tests over 7 to 8 years , 2000, Psychological Medicine.

[14]  T. del Ser,et al.  Poststroke dementia : clinical features and risk factors. , 2000, Stroke.

[15]  J. Gallo,et al.  Performance characteristics of a two-stage dementia screen in a population sample. , 2000, Journal of clinical epidemiology.

[16]  I. Deary,et al.  Correlates of Informant-Rated Cognitive Decline after Stroke , 2000, Cerebrovascular Diseases.

[17]  R. Jacoby,et al.  Can an informant questionnaire be used to predict the development of dementia in medical inpatients? , 1999, International journal of geriatric psychiatry.

[18]  D. Leys,et al.  Confusional state in stroke: relation to preexisting dementia, patient characteristics, and outcome. , 1999, Stroke.

[19]  A. Mackinnon,et al.  Combining cognitive testing and informant report to increase accuracy in screening for dementia. , 1998, The American journal of psychiatry.

[20]  K. Rockwood,et al.  Retrospective Diagnosis of Dementia Using an Informant Interview Based on the Brief Cognitive Rating Scale , 1998, International Psychogeriatrics.

[21]  D. Leys,et al.  Preexisting dementia in stroke patients. Baseline frequency, associated factors, and outcome. , 1997, Stroke.

[22]  H. Christensen,et al.  A quantitative review of cognitive deficits in depression and Alzheimer-type dementia , 1997, Journal of the International Neuropsychological Society.

[23]  M. Ooms,et al.  [Abbreviated form of the Informant Questionnaire on cognitive decline in the elderly]. , 1997, Tijdschrift voor gerontologie en geriatrie.

[24]  Anthony F Jorm.  Methods of Screening for Dementia: A Meta‐Analysis of Studies Comparing an Informant Questionnaire with a Brief Cognitive Test , 1997, Alzheimer disease and associated disorders.

[25]  F. Bermejo,et al.  Screening of dementia in community‐dwelling elderly through informant report , 1997, International journal of geriatric psychiatry.

[26]  J. D. de Jonghe.  DIFFERENTIATING BETWEEN DEMENTED AND PSYCHIATRIC PATIENTS WITH THE DUTCH VERSION OF THE IQCODE , 1997, International journal of geriatric psychiatry.

[27]  M. Barquero,et al.  Application of a Spanish Version of the “Informant Questionnaire on Cognitive Decline in the Elderly” in the Clinical Assessment of Dementia , 1997, Alzheimer disease and associated disorders.

[28]  J. Carlin,et al.  THE PREDICTIVE VALUE OF DEMENTIA SCREENING INSTRUMENTS IN CLINICAL POPULATIONS , 1997, International Journal of Geriatric Psychiatry.

[29]  D. Ames,et al.  Burden and Stress on Relatives (Informal Carers) of Dementia Sufferers in Psychogeriatric Nursing Homes , 1996 .

[30]  A. Mackinnon,et al.  A comparison of alternative methods of screening for dementia in clinical settings. , 1996, Archives of neurology.

[31]  A. Mackinnon,et al.  Informant ratings of cognitive decline of elderly people: relationship to longitudinal change on cognitive tests. , 1996, Age and ageing.

[32]  L. Thomas.  Neuropsychological correlates of amyloid precursor protein in Alzheimer's disease. , 1996, International journal of nursing practice.

[33]  Anthony F Jorm,et al.  Further data on the validity of the informant questionnaire on cognitive decline in the elderly (IQCODE) , 1996 .

[34]  C. Wolfson,et al.  Validation of a French Version of an Informant-Based Questionnaire as a Screening Test for Alzheimer's Disease , 1995, British Journal of Psychiatry.

[35]  A. Mackinnon,et al.  The Psychogeriatric Assessment Scales: a multidimensional alternative to categorical diagnoses of dementia and depression in the elderly , 1995, Psychological Medicine.

[36]  H C Liu,et al.  The Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) as a screening tool for dementia for a predominantly illiterate chinese population , 1995, Neurology.

[37]  C. Masters,et al.  Comparison of clinical state, retrospective informant interview and the neuropathologic diagnosis of alzheimer's disease , 1994 .

[38]  Anthony F Jorm.  A short form of the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE): development and cross-validation , 1994, Psychological Medicine.

[39]  D. Goldberg,et al.  Psychiatric Morbidity in Older People with Moderate and Severe Learning Disability , 1993, British Journal of Psychiatry.

[40]  H. Christensen,et al.  Short report: Effect of premorbid intelligence on the Mini‐Mental State and IQCODE , 1992 .

[41]  A. Mackinnon,et al.  Performance of the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) as a screening test for dementia , 1991, Psychological Medicine.

[42]  Anthony F Jorm,et al.  General practitioners' detection of depression and dementia in elderly patients , 1990, The Medical journal of Australia.

[43]  Anthony F Jorm,et al.  The Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE): socio-demographic correlates, reliability, validity and some norms , 1989, Psychological Medicine.

[44]  A. Korten,et al.  Assessment of Cognitive Decline in the Elderly by Informant Interview , 1988, British Journal of Psychiatry.

[45]  M. Schuurmans,et al.  The Delirium Observation Screening Scale: a screening instrument for delirium. , 2003, Research and theory for nursing practice.

[46]  F. Bellavance,et al.  Systematic detection and multidisciplinary care of delirium in older medical inpatients : a randomized trial , 2002 .

[47]  J. Rojahn,et al.  Psychometric evaluation of a measure of cognitive decline in elderly people with mental retardation. , 1998, Research in developmental disabilities.

[48]  R. Jacoby,et al.  Cognitive impairment in medical inpatients. I: Screening for dementia--is history better than mental state? , 1997, Age and ageing.

[49]  Anthony F Jorm.  Assessment of cognitive impairment and dementia using informant reports , 1996 .

[50]  F. Bermejo,et al.  The Screening of Mild Dementia with a Shortened Spanish Version of the “Informant Questionnaire on Cognitive Decline in the Elderly” , 1995, Alzheimer disease and associated disorders.

[51]  Anthony F Jorm.  12 Use of Informants' Reports to Study Memory Changes in Dementia , 1992 .

[52]  Anthony F Jorm,et al.  Assessment of cognitive decline in dementia by informant questionnaire , 1989 .