[Aging effect on frontal lobe function-evaluation by the new modified Wisconsin Card Sorting Test].

New Modified Wisconsin Card Sorting Test (WCST) was administered to ninety-five individuals to assess the effects of age on frontal lobe functions. The correlations between ages and scores were evaluated in the following five subgroups which were classified into whole subjects (TOL, n = 95), normals and patients who were neurologically diagnosed as only having cervical spondylosis (NOR, n = 20), individuals whose age-corrected total intelligence quotients (TIQ) by the Wechsler Adult Intelligence Scale were higher than or equal to 100 (HIQ, n = 30), individuals whose TIQ were less than 100 (LIQ, n = 27), and individuals whose Mini-Mental State Examination scores were full (MMS, n = 28). Scores of the WCST including Categories Achieved, Total Errors, Difficulty of Maintaining Set and Perseveration were significantly correlated to ages in four groups such as TOL, NOR, HIQ, and MMS. The correlation of WCST's scores of the four groups indicated almost the same tendency. Some subcategories of the WCST, indicating perservation which were characteristic signs of the frontal lobe dysfunction correlated with ages in these four groups. The groups indicating NOR, HIQ, and MMS were thought to be regarded as being normal controls. And, the scores of Mini-Mental State Examination were not correlated with ages. So, the WCST scores of the MMS group were no thought to be effected by the age-related decline of intelligence. The results might suggest that the age-related decline of the frontal lobe function precedes that of intelligence.