The relation between morbidity and cognitive performance in a normal aging population.
BACKGROUND
Factors related to physical health have been implicated in both normal and pathological aging of cognitive abilities. To substantiate this notion, we studied existing morbidity, as diagnosed by the general practitioner according to well-defined criteria, as a potential predictor of cognitive test performance.


METHODS
A sample of 1360 individuals, aged 24-81 years and living in the community, was stratified for age, sex, and general ability. Active and total morbidity in this group were classified according to the International Classification of Primary Care. Neurocognitive tests were used to assess the domains of verbal memory, sensorimotor speed, and cognitive flexibility.


RESULTS
Multiple regression analyses with adjustment for age, sex, and educational level showed both insulin-dependent and noninsulin-dependent diabetes to be negatively associated with all cognitive measures. More specific negative associations were found for chronic bronchitis (performance speed) and presbyacusia (memory). Single or aggregated cardiovascular morbidity (including hypertension) was unrelated to test performance.


CONCLUSIONS
Existing morbidity as a whole contributes only modestly (up to 3.5%) to total variance in cognitive function. However, some specific, relatively common diseases of the elderly, such as diabetes and chronic bronchitis, may aggravate the age-related decline in cognitive ability.
van Boxtel
M P
MP
Department of Psychiatry and Neuropsychology, Maastricht University, The Netherlands. martin.vanboxtel@np.unimaas.nl
Buntinx
F
F
Houx
P J
PJ
Metsemakers
J F
JF
Knottnerus
A
A
Jolles
J
J
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology* / Q000523:psychology*; D001991:Bronchitis / Q000523:psychology; D002318:Cardiovascular Diseases / Q000523:psychology; D003071:Cognition / Q000502:physiology*; D003430:Cross-Sectional Studies; D003922:Diabetes Mellitus, Type 1 / Q000523:psychology; D003924:Diabetes Mellitus, Type 2 / Q000523:psychology; D005260:Female; D006304:Health Status; D006801:Humans; D008297:Male; D008569:Memory Disorders / Q000523:psychology; D008875:Middle Aged; D009017:Morbidity; D009483:Neuropsychological Tests; D012016:Reference Values; D012044:Regression Analysis