Concentrations of ACT (mean=125.5 mg/dl, SD=59.3) and MAC (mean=423.9 mg/dl, SD=172.4) were higher in this group of nursing home residents (N=403) than in a normal adult population, but this was not unexpected in elderly subjects sampled during routine clinic visits. Residents with the following ranges of laboratory values had significantly higher ACT concentrations than those without these abnormalities: creatinine greater than 1.5 (z=2.66, N=403, p=0.008), WBC count greater than 10,000 (z=3.74, N=403, p=0.0002), erythrocyte segmentation rate greater than 75 (z=3.21, N=403, p=0.001), and hematocrit less than 30 (z=3.04, N=403, p=0.002). After cases with any of these abnormalities were excluded, 202 subjects remained. Ninety-three of these subjects had a Mini-Mental State within 6 months of blood tests; these subjects were used for subsequent analyses. APOE genotypes were available for 87 of the 202 subjects.
The 93 subjects with recent Mini-Mental State results were divided into two groups based on their scores: 60 subjects had scores of 20 or less and 33 had scores higher than 20. The dementia diagnoses based on comprehensive chart review for the subjects with Mini-Mental State scores of 20 or less were Alzheimer's disease (N=51), dementia with cerebrovascular disease (N=7), and dementia with parkinsonism (N=2). The two Mini-Mental State groups did not differ in age (mean=86.2 years, SD=8.4, versus mean=86.5 years, SD=7.7, respectively) (z=0.04, N=93, p>0.10) or percent female (82% versus 72%, respectively) (χ2=1.17, df=1, p>0.10). These two groups also did not differ in race, religion, or occupation. Patients with Mini-Mental State scores of 20 or less had higher ACT concentrations than those with Mini-Mental State scores greater than 20 (z=2.70, N=93, p=0.007) (T1). MAC concentrations were not significantly different between the two Mini-Mental State groups (z=0.36, N=93, p>0.10). Significant correlations were observed between ACT concentrations and Mini-Mental State scores (r=–0.39, df=91, p<0.0001). Patients with at least one APOE ε4 allele (N=22) had nonsignificantly lower Mini-Mental State scores than those with no APOE ε4 alleles (N=65) (mean=13.6, SD=9.6, versus mean=16.5, SD=8.3, respectively) (z=1.28, N=87, p>0.10). ACT levels of individuals with or without an APOE ε4 allele were not significantly different (z=1.76, N=87, p=0.08). No significant relationship was found between MAC concentrations and Mini-Mental State scores (r=0.01, df=91, p>0.10) or presence or absence of APOE ε4 (z=0.74, N=87, p>0.10).