Intelligence & cognition

Crystallized intelligence


LASA037 (C and F)
LASA237 (C and F)

Contact: Hannie Comijs

Background
Crystallized intelligence is the ability to use skills, knowledge  and experience and is considered one’s intellectual achievement, as demonstrated largely through one's vocabulary and general knowledge. In older adults it is considered a stable characteristic, and only declines when people are seriously demented.

In most studies with cognitive outcome measures the level of education is entered in the model  in order to adjust for premorbid or general level of intelligence. However, it is questionable if this is a reliable measure for the level of intelligence among the elderly, because many people were not able to follow suitable education at the time they were young. The associations between level of intelligence and cognitive test performances (beta's varying between 0.30 and 0.50) was up to twice as strong as the association with level of education (results not shown). The strongest associations were found between the level of verbal intelligence and the MMSE. This suggests that it is important to include the level of intelligence as a covariate in studies using the MMSE and any other cognitive test instead of the level of education.

Measurement instrument in LASA
Crystallized intelligence is assessed with the vocabulary test, a subtest of the Groninger Intelligentie Test (GIT; Luteijn & van der Ploeg, 1983). It measures In this subtest 20 words of increasing difficulty are presented of which the respondent has to choose the synonym out of five alternatives. The total score ranged between 0-20, with higher scores reflecting higher level of verbal intelligence. It is just measured once in each cohort because it is considered a stable characteristic in older adults.  

In LASA037 the following *GIT_A1 to A3 are used to practice the test. The variables *GIT_1 to *GIT_20 are the real items. The sum score of these items is given in the file LASAC237 and LASAF237 respectively, higher scores represent better performance.

Availability of GIT vocabulary test per wave1:

 

B

C

D

E

 
2B*

F

G

H



3B*

MB*

I*

GIT-VT

 

-

Ma

-

-

-

Ma

-

-

-

-

-

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 (Under Construction);
   I=Under Construction

Ma=data collected in main interview

Previous use in LASA
GIT was used as covariate in the study of Comijs et al. 2001 and 2004.

References

  1. Comijs HC, Jonker C, Beekman ATF, Deeg DJH. (2001) The association between depressive symptoms and cognitive decline in community-dwelling elderly persons. International Journal of Geriatric Psychiatry, 16: 361-367.
  2. Comijs HC, van Tilburg T, Geerlings SW, Jonker C, Deeg DJH, van Tilburg W, Beekman ATF. Do severity and duration of depressive symptoms predict cognitive decline older persons? Results of the Longitudinal Aging Study Amsterdam. Aging Clinical and Experimental Research, 2004, 16 (3): 226-232.
  3. Luteijn F, van der Ploeg FAE.1983. Groninger Intelligentie Test. Handleiding (Groninger Intelligence Test. Manual). Lisse: Swets, Zeitlinger BV.