These results support a significant association between hippocampal atrophy and executive dysfunction as a non-memory cognitive impairment in patients with early AD and A-MCI.

Background: Previous research has described the executive dysfunction that occurs in patients with amnestic-mild cognitive impairments (A-MCI) and early-stage Alzheimer's disease (EAD), which are comparatively similar stages of dementia. The aim of the present cross-sectional study is to evaluate executive dysfunction using the Frontal Assessment Battery (FAB) screening test in two groups and to investigate the interaction with other cognitive impairments. Methods: Among 170 consecutive patients with Alzheimer's disease or A-MCI, we recruited 48 subjects who were under 75 years of age and had been diagnosed as having either A-MCI or EAD. We then compared the total and the subtest scores of the mini-mental state examination (MMSE) and the FAB between the two groups. Moreover, we investigated the statistical interactive associations of the FAB subtest scores with the influential MMSE subtest scores or the diagnosis (A-MCI or EAD). Results: No significant differences in the age, sex ratio, duration of illness, and education years were observed between the two groups. However, significant differences in the FAB total and subtest scores (conflicting instructions and go/no-go) were found between the two groups. Furthermore, significant differences in the MMSE total and subtest scores (orientation, memory delayed recall, and attention and calculation) were also noted between the two groups. In a generalized linear model analysis, only two FAB subtest scores (conflicting instructions and go/no-go) were significantly influenced by the diagnosis (A-MCI or EAD) in a manner that was independent of the interaction with the orientation or memory delayed recall. Conclusion:The present findings suggest that the FAB total score and subtest scores reflecting interference performances (conflicting instructions and go/no-go) significantly declined in patients with EAD, independent of the disorientation and memory disorder. Such characteristics of neuropsychological screening test scores may be useful to clinicians for differentiating EAD and A-MCI at bedside.

Background: To address the functional roles of genetic polymorphisms of brain-derived neurotrophic factor (BDNF) in Alzheimer's disease (AD) from a neuropsychological aspect, we used a cross-sectional study design to investigate the association between novel single nucleotide polymorphisms (SNPs) of the BDNF gene (Val66Met (G196A) and C270T) and the Frontal Assessment Battery (FAB) score, which reflects executive function as a non-memory cognitive impairment. Methods: One hundred and sixty-nine outpatients with AD or amnestic mild cognitive impairment (A-MCI) were recruited to the study and divided into three genotypic groups for each representative BDNF functional polymorphism as follows: (i) Val66Met (G196A): G/G (n = 45), G/A (n = 104), and A/A (n = 20); and (ii) C270T: C/C (n = 160), C/T (n = 9), and T/T (n = 0). Then, age, sex ratio, duration of illness (months), education years, Mini-Mental State Examination (MMSE) score, behavioral pathology in Alzheimer disease (Behave-AD) score, Clinical Dementia Rating (CDR) ratio, and total and subtest FAB scores were compared between the genotypic groups for each SNP. Results: Significant differences were found in the total (P < 0.01) and subtest (conflicting instructions and prehension behavior; P < 0.01) FAB scores between the C270T polymorphism groups (C/C and C/T), but not among the G196A polymorphism groups. However, no significant differences in age, sex ratio, duration of illness (months), education years, Behave-AD score, CDR ratio, or MMSE score (reflecting attention and memory function) were found between the individual polymorphism genotypes (G196A and C270T). Conclusion: Of the known BDNF polymorphisms, the C270T SNP may influence executive dysfunction as a non-memory cognitive impairment in Japanese patients with AD.