Intelligence & cognition

Informant Questionnaire of Cognitive Decline in The Elderly (IQCODE)


LASA607

Contact: Hannie Comijs

Background
Loss-to-follow up is among others associated with cognitive decline. Persons who become demented are for instance no longer able to participate in the study. To obtain an impression of possible cognitive decline or dementia from the persons that are no longer able to participate in the study, we ask the proxy some questions about cognitive functioning of their relative.

Measurement instruments in LASA
The Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE; Jorm & Jacomb, 1989) is a short questionnaire designed to assess cognitive decline and dementia in older persons. The original form contains 26 items, a shortened 16 question form of the IQCODE has also been validated (Jorm, 1994).

In LASA an adapted form of the IQCODE was used and included 6 questions concerning decline in the last 10 years, namely: remembering conversations; remembering his/her address and phone number; handling known domestic appliances; making decisions on everyday affairs; handling money for groceries; handling finances. The questions were scored on a 5-point scale: 1=much better, 3=unchanged, 5 = much worse, which resulted in a sumscore ranging from 1 to 30, higher scores indicating more cognitive decline.

The IQCODE was administered once (at C) by phone to respondents who could or would not participate in the complete interview, and from wave C on administered by phone to the proxy of the respondent who could or would not participate in the complete interview.

Questionnaires
LASAC607 / LASAD607 / LASAE607 / LASAF607 / LASAG607 / LASAH607 / LASAI607 (telephone interview with proxy, in Dutch)

in C also with respondent

Variable information
LASAC607 / LASAD607 / LASAE607 / LASAF607 / LASAG607 / LASAH607 / LASAI607
(pdf)


Availability of information per wave1:

 

B

C

D

E


2B*

F

G

H



3B*

MB*

I

IQCODE

-

Tel_prox
Tel_resp

Tel_prox

Tel_prox

-

Tel_prox

Tel_prox

Tel_prox

-

-

Tel_prox

1 More information is available on:
http://www.lasa-vu.nl/data/lasa/sampleLASAdatacollection.html

* 2B=baseline second cohort;
   3B=baseline third cohort;
   MB=migrants: baseline first cohort

Tel_prox=data collected in telephone interview with proxy;
Tel_resp=data collected in telephone interview with respondent (only at C)

Previous use in LASA
The IQCODE is used in a composed variable comprising persons with a probable dementia diagnosis (see probable dementia). This variable is used in a paper that aimed to develop classification models for use in primary care to aid early identification of persons at risk for persistent cognitive decline (Van den Kommer et al 2008).

References

  1. Jorm AF, Jacomb PA. The Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE): socio-demographic correlates, reliability, validity and some norms. Psychol Med. 1989 Nov;19(4):1015-22.
  2. 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.
  3. Van den Kommer TN, Comijs HC, Dik MG, Jonker C, & Deeg DJH. Development of classification models for early identification of persons at risk for persistent cognitive decline. Journal of Neurology, 2008, 255(10): 1486-94.