In previous studies, the association between higher MMSE scores and CD was attributed to a ceiling effect.3,4 Several studies have shown that the ε4 allele is a risk factor for cognitive impairment and decline44–46; however, no studies found an effect of APOE genotype on cognitive functioning.47–49 The present findings are comparable to those of previous investigations, which indicates that our study population was not unusual. The gene discussed is APOE; the disease is Cognitive impairment.