Alessandra Bizzarro

Effect of a CYP2D6 polymorphism on the efficacy of donepezil in patients with Alzheimer disease.

Objective: To evaluate the influence of the single nucleotide polymorphism rs1080985 in the cytochrome P450 2D6 (CYP2D6) gene on the efficacy of donepezil in patients with mild to moderate Alzheimer disease (AD). Methods: This was a multicenter, prospective cohort study of 127 white patients with AD according to the National Institute of Neurological and Communicative Disorders and Stroke–Alzheimer’s Disease and Related Disorders Association Work Group criteria. Patients were treated with donepezil 5–10 mg/daily for 6 months. Cognitive and functional statuses were evaluated at baseline and at 6-month follow-up. Response to therapy was defined according to the National Institute for Health and Clinical Excellence criteria. Compliance and drug-related adverse events were also evaluated. The analyses identifying the CYP2D6 and APOE polymorphisms were performed in blinded fashion. Results: At 6-month follow-up, 69 of 115 patients (60%) were responders and 46 patients (40%) were nonresponders to donepezil treatment. A significantly higher frequency of patients with the G allele of rs1080985 was found in nonresponders than in responders (58.7% vs 34.8%, p = 0.013). Logistic regression analysis adjusted for age, sex, Mini-Mental State Examination score at baseline, and APOE demonstrated that patients with the G allele had a significantly higher risk of poor response to donepezil treatment (odds ratio 3.431, 95% confidence interval 1.490–7.901). Conclusions: The single nucleotide polymorphism rs1080985 in the CYP2D6 gene may influence the clinical efficacy of donepezil in patients with mild to moderate Alzheimer disease (AD). The analysis of CYP2D6 genotypes may be useful in identifying subgroups of patients with AD who have different clinical responses to donepezil.

Apolipoprotein E ε4 Allele Differentiates the Clinical Response to Donepezil in Alzheimer’s Disease

The existence of an association between apolipoprotein E (APOE) and Alzheimer’s disease (AD) has been reported in several studies. The possession of an ApoE ε4 allele is now considered a genetic risk factor for sporadic AD. There has been a growing agreement about the role exerted by the ApoE ε4 allele on the neuropsychological profile and the rate of cognitive decline in AD patients. However, a more controversial issue remains about a possible influence of the APOE genotype on acetylcholinesterase inhibitor therapy response in AD patients. In order to address this issue, 81 patients diagnosed as having probable AD were evaluated by a complete neuropsychological test battery at the time of diagnosis (baseline) and after 12–16 months (retest). Patients were divided into two subgroups: (1) treated with donepezil at a dose of 5 mg once a day (n = 41) and (2) untreated (n = 40). Donepezil therapy was started after baseline evaluation. The APOE genotype was determined according to standardized procedures. We evaluated the possible effect of the APOE genotype on the neuropsychological tasks in relation to donepezil therapy. The statistical analysis of the results showed a global worsening of cognitive performances for all AD patients at the retest. Differences in the clinical outcome were analysed in the four subgroups of AD patients for each neuropsychological task. ApoE ε4 carriers/treated patients had improved or unchanged scores at retest evaluation for the following tasks: visual and verbal memory, visual attention and inductive reasoning and Mini Mental State Examination. These results indicate an effect of donepezil on specific cognitive domains (attention and memory) in the ApoE ε4 carriers with AD. This might suggest an early identification of AD patients carrying at least one ε4 allele as responders to donepezil therapy.

Methylenetetrahydrofolate reductase and angiotensin converting enzyme gene polymorphisms in two genetically and diagnostically distinct cohort of Alzheimer patients

The role of methylenetetrahydrofolate reductase (MTHFR) and angiotensin converting enzyme (ACE) gene polymorphisms as risk factors for the occurrence of Alzheimers disease (AD) is still controversial. In this study, we investigated the common MTHFR C677-->T and ACE insertion/deletion (I/D) gene polymorphisms as risk factors for AD in two genetically and diagnostically distinct cohort of Alzheimers patients. We analyzed a neuropathologically confirmed American cohort of 124 AD patients and 97 elderly controls, and a clinically diagnosed Italian cohort of 126 probable AD cases, 106 elderly controls, and a community-based sample of 1232 subjects aged under 65 years. No difference was found in polymorphism distribution between cases and controls in both study cohorts. We also tested a possible association between the polymorphisms investigated. No interaction was found between the MTHFR and ACE alleles. Moreover, no association was found for the ACE and MTHFR polymorphisms with age at onset, disease duration and MMSE score at observation. Thus, in our study, MTHFR C677-->T and ACE I/D polymorphisms do not appear to confer an added risk for AD.

Apolipoprotein E ε4 Allele Differently Affects the Patterns of Neuropsychological Presentation in Early- and Late-Onset Alzheimer’s Disease Patients

The presence of the apolipoprotein E (APOE) Ε4 allele is a definite risk factor for the onset of Alzheimer’s disease (AD). Its presence seems to affect especially the memory in the early stage of the disease, but the effect on the progression of the disease and survival is still controversial. Some longitudinal studies could be influenced by variables other than APOE, such as the response to medical treatment, rehabilitation therapy and inclusion of patients at different stages of progression at baseline. Moreover, the inclusion in the same study sample of patients of different ages at onset of the disease (below 65 or above 80 years) appears arbitrary. In our study, we evaluated a population of newly diagnosed untreated AD patients at their first neuropsychological examination and with the onset of their first symptoms not longer than 3 years ago. In order to analyse the different effects of the APOE Ε4 allele on the different ages at the onset of the disease, we split the study sample into two groups: (1) subjects under 65 years [early-onset AD (EOAD); n = 30] and subjects over 70 years [late-onset AD (LOAD); n = 41], excluding subjects with an age of onset between 66 and 69 years. Our results show that the APOE Ε4 allele carriers are characterised by a different neuropsychological pattern at the disease onset; however, only in the EOAD group is this effect significant: in EOAD, the Ε4 allele carriers obtained worse performances in learning, long-term verbal memory and general intelligence tasks. On the contrary, in LOAD patients, the pattern of cognitive impairment at the onset is not dependent on the possession of an Ε4 allele in the genotype. Such data could suggest a careful control of the study sample concerning age at the onset of the disease since APOE could play a different role in EOAD and LOAD mainly due to the different pathogenic mechanism at the onset and evolution of AD.

Role of cytochrome P4502D6 functional polymorphisms in the efficacy of donepezil in patients with Alzheimer's disease.

Objective Cytochrome P450 (CYP) 2D6 enzyme is the major responsible for the metabolism of donepezil, an inhibitor of acetyl cholinesterase currently used for the symptomatic treatment of mild-to-moderate Alzheimers disease (AD). Functional polymorphisms in the CYP2D6 gene may affect enzyme activity and thus, the metabolism of donepezil. The aim of this study was to evaluate the effect of 16 functional polymorphisms in the CYP2D6 gene on the clinical response to donepezil treatment in patients with mild-to-moderate AD. Methods In this multicenter prospective cohort study we evaluated 57 unrelated Caucasians clinically diagnosed as AD according to the National Institute of Neurological and Communicative Disorders and Stroke-Alzheimers Disease and Related Disorders Association Work Group criteria. Patients were treated with donepezil (5–10 mg/daily) for 6 months. The response to donepezil treatment was evaluated at 6-month follow-up according to the National Institute for Health and Clinical Excellence requirements. The identification of 16 clinically relevant CYP2D6 gene variants was performed by a high-throughput genetic analysis. Results Thirty-eight of 57 patients (67%) were responders and 19 patients (33%) were nonresponders to donepezil treatment. A significantly higher frequency of gene variants conferring decreased or absent enzyme activity was observed in responder than in nonresponder patients (73.68% vs. 36.84%; P=0.005). The presence of gene variants conferring decreased or absent activity of the CYP2D6 enzyme was significantly associated with a clinical response to donepezil treatment (odds ratio=6.286; 95% confidence interval=1.828–21.667). Conclusions Functional polymorphisms in the CYP2D6 gene can influence the clinical efficacy of donepezil. The analysis of CYP2D6 genotypes may be useful in identifying subgroups of AD patients with different clinical response to donepezil treatment.

Possible relationship between Al/ferritin complex and Alzheimer's disease

OBJECTIVES Ferritin is the main iron-storage protein capable of containing thousands of iron atoms. However, ferritin can bind in vitro other atoms such as aluminum and it has been shown that also in vivo atoms other than iron, as aluminum and zinc, are present in large amounts in ferritin. Since aluminum appears to be involved in the development of Alzheimers disease, in the present study the specific content of aluminum in ferritin of Alzheimers patients was analyzed and compared with other control groups. DESIGN AND METHODS The content of Fe, Al and Zn of blood ferritin was measured by mass spectrometry in patients with Alzheimers disease and compared with other clinical and control groups. RESULTS The results obtained confirm the hypothesis of a functional role of ferritin as a regulatory protein of toxic metals and clearly indicate that ferritin from Alzheimers patients has a content of aluminum higher than that of controls. CONCLUSIONS The specific aluminum content of ferritin seems to be related to different disease stages of Alzheimers disease. This result confirms the hypothesis of aluminum as a possible factor inducing the Alzheimers disease and opens the ways to possible new diagnostic tests.

Clusters of Cognitive and Behavioral Disorders Clearly Distinguish Primary Progressive Aphasia from Frontal Lobe Dementia, and Alzheimer’s Disease

Background/Aims: Frontal lobe dementia (FLD) and primary nonfluent progressive aphasia (PnPA) are two forms of frontotemporal lobe degeneration. The relationship between these conditions remains unclear. Our study aimed to better define the behavioral and cognitive clusters characterizing PnPA patients. Methods: We cognitively and behaviorally evaluated three groups of newly diagnosed patients affected by Alzheimer’s disease (AD, n = 20), FLD (n = 22) and PnPA (n = 10), in order to assess the cognitive-behavioral pattern of PnPA, compared to both FLD and AD. Results: We found, as expected, worse performances in episodic memory in AD, of both the verbal fluency and naming tasks in PnPA, while FLD mainly showed behavioral disorders associated with an unremarkable deficit in the executive tasks. PnPA was not characterized by any significant behavioral disorders. Factor analysis-extracted three main factors (‘mnesic’, ‘behavioral’ and ‘linguistic’) clearly correlated to each group. A discriminant analysis based on the extracted factors correctly classified 84.6% of all patients. Conclusion: The evidence of a characteristics cognitive profile, without any significant behavioral changes, highlights that PnPA is different from other forms of frontotemporal lobe degeneration regarding both the cognitive and behavioral patterns; thus, it should be considered independently in further studies.

The role of brain infarcts and hippocampal atrophy in subcortical ischaemic vascular dementia

Abstract.We investigated if, in patients with vascular lesions, the variable that best discriminated demented from non–demented patients was the severity of the vascular pathology or the degree of hippocampal atrophy. A total of 39 patients multiple subcortical infarcts, who could be considered as possible vascular dementia with small vessel pathology, with underwent a neuropsychological study and brain magnetic resonance imaging (MRI) DSM IV criteria supported by neuropsychological data were used to distinguish demented from non–demented patients. The MRI study took into account the degree of hippocampal atrophy (hippocampal height and interuncal distance) and the severity of vascular pathology (number of brain infarcts). The distribution of lesions and a factor analysis showed that hippocampal atrophy is a better predictor of dementia than the number of brain infarcts. Multiple subcortical infarcts alone are probably not able to cause clinical dementia but the presence of vascular lesions increases the expression of concomitant Alzheimer’s disease.

The APOE Gene Locus in Frontotemporal Dementia and Primary Progressive Aphasia

OBJECTIVE To investigate the role of the apolipoprotein E (APOE) locus in frontotemporal dementia (FTD) and primary progressive aphasia (PPA). DESIGN Case-control study. SETTING Neurology clinic, Rome, Italy. PATIENTS Eighty-six patients with a clinical diagnosis of sporadic FTD, including 32 patients with a clinical diagnosis of PPA, and 99 nondemented cognitively intact control subjects. MAIN OUTCOME MEASURES Genotype analysis of the 3 single-nucleotide polymorphisms rs449647, rs769446, and rs405509 in the promoter region of the APOE gene and of the 2 single-nucleotide polymorphisms rs429358 and rs7412 forming the common apoE polymorphism. RESULTS Significant associations with FTD were observed for genotypes rs449647 A/T (odds ratio [OR], 2.1; 95% confidence interval [CI], 1.0-4.5), rs769446 T/C (OR, 4.4; 95% CI, 1.9-10.2), and APOE ε3/ε4 (OR, 4.1; 95% CI, 1.6-10.9). Significant associations with PPA were also observed for genotypes APOE ε3/ε4 (OR, 22.5; 95% CI, 1.2-229.4) and ε4/ε4 (OR, 7.5; 95% CI, 2.6-21.6). Significant associations with FTD were observed for haplotypes A-C-G-C-C (OR, 5.6; 95% CI, 1.4-21.5) and T-T-T-C-C (OR, 5.2; 95% CI, 1.1-24.0). Significant associations with PPA were also observed for haplotypes A-T-T-T-C (OR, 0.4; 95% CI, 0.2-0.9) and A-T-T-C-C (OR, 5.2; 95% CI, 1.4-19.3). CONCLUSION Although the physiological role of apoE in FTD and PPA needs further investigations, our results suggest an involvement of the APOE gene locus in the genetics of FTD and PPA.

The missing ApoE allele.

The human apoE gene (APOE, GenBank accession AF261279) shows a common polymorphism, with the three ɛ2, ɛ3 and ɛ4 alleles resulting from the haplotypes of two C→T SNPs. However, whereas the three common T‐T, T‐C and C‐C haplotypes corresponding to the ɛ2, ɛ3 and ɛ4 alleles are well known, the last C‐T haplotype (GenBank accession AY077451), encoding a fourth apoE allele, has rarely been reported. We detected this fourth allele in a Caucasian patient with motor neuron disease (MND). According to the literature we refer to this allele as ɛ3r. Although several explanations may be proposed for its formation, the existence of this fourth allele is consistent with the evolutionary hypothesis generally accepted for the apoE alleles. The rarity and physiological role of ɛ3r remains to be explained, and requires further investigation.