Decline of frontal lobe functions in subjects with age-associated memory impairment

Abstract

Objective: To assess frontal lobe functions of subjects with age-associated memory impairment (AAMI) and to examine whether performance on neuropsychological tests is correlated with the volume of the frontal lobes in magnetic resonance imaging.

Design: Cross-sectional two-group comparison.

Setting: The Memory Research Clinic of Kuopio University and the Magnetic Resonance Imaging Center of Kuopio University Hospital.

Participants: Ninety subjects (mean age, 70.5 years), 43 with AAMI diagnosed according to National Institute of Mental Health criteria and 47 age-matched healthy controls.

Measurements: Four neuropsychological tests were used to assess frontal lobe function: Verbal Fluency Test (VFT), Modified Wisconsin Card Sorting Test (WCST), Trail Making Test (TMT), and Stroop Test (ST). A 1.5-T magnetic resonance imager was used for volume measurements.

Results: The AAMI subjects scored significantly worse on the WCST, ST, and TMT compared with controls (ANCOVA, adjusted for age and education, p < 0.05). The frontal lobe volumes did not differ between AAMI subjects and controls.

Conclusions: AAMI subjects appear to be impaired not only in tests assessing memory but also in tests of executive functions. This finding agrees with previous reports suggesting a central role for frontal dysfunction in memory loss of elderly people.