Metrifonate treatment of AD: influence of APOE genotype

Alzheimer's disease phenotype based upon the carrier status of the apolipoprotein E ɛ4 allele

The apolipoprotein E ɛ4 allele (APOE4) is universally acknowledged as the most potent genetic risk factor for Alzheimer's disease (AD). APOE4 promotes the initiation and progression of AD. Although the underlying mechanisms are unclearly understood, differences in lipid-bound affinity among the three APOE isoforms may constitute the basis. The protein APOE4 isoform has a high affinity with triglycerides and cholesterol. A distinction in lipid metabolism extensively impacts neurons, microglia, and astrocytes. APOE4 carriers exhibit phenotypic differences from non-carriers in clinical examinations and respond differently to multiple treatments. Therefore, we hypothesized that phenotypic classification of AD patients according to the status of APOE4 carrier will help specify research and promote its use in diagnosing and treating AD. Recent reviews have mainly evaluated the differences between APOE4 allele carriers and non-carriers from gene to protein structures, clinical features, neuroimaging, pathology, the neural network, and the response to various treatments, and have provided the feasibility of phenotypic group classification based on APOE4 carrier status. This review will facilitate the application of APOE phenomics concept in clinical practice and promote further medical research on AD.

Acute response to cholinergic challenge predicts long-term response to galantamine treatment in patients with Alzheimer's Disease

BACKGROUND

Cholinesterase inhibitors (CEIs) have been shown to improve cognitive functioning in Alzheimer's Disease (AD) patients, but are associated with multiple side effects and only 20-40% of the patients clinically improve. In this study, we aimed to investigate the acute pharmacodynamic (PD) effects of a single dose administration of galantamine on CNS functioning in mild to moderate AD patients and its potential to predict long-term treatment response.

METHODS

This study consisted of a challenge and treatment phase. In the challenge phase, a single dose of 16 mg galantamine was administered to 50 mild to moderate AD patients in a double-blind, placebo-controlled cross-over fashion. Acute PD effects were monitored up to 5 hours after administration with use of the NeuroCart CNS test battery and safety and pharmacokinetics were assessed. In the treatment phase, patients were treated with open-label galantamine according to regular clinical care. After 6 months of galantamine treatment, patients were categorized as either responder or as non-responder based on their MMSE, NPI and DAD scores. An analysis of covariance was performed to study the difference in acute PD effects during the challenge phase between responders and non-responders.

RESULTS

A single dose of galantamine significantly reduced saccadic reaction time (-0.0099; 95%CI=-0.0195,-0.0003; p=.0430), absolute frontal EEG parameters in alpha (-14.9; 95%CI=-21.0,-8.3; p=.0002), beta (-12.6; 95%CI=-19.4,-5.3; p=.0019) and theta (-17.9; 95%CI=-25.0,-10.0; p=.0001) frequencies. Relative frontal (-1.669; 95%CI=-2.999,-0.339; p=.0156) and occipital (-1.856; 95%CI=-3.339,-0.372; p=.0166) EEG power in theta frequency and relative occipital EEG power in the gamma frequency (1.316; 95%CI=0.158,2.475; p=.0273) also increased significantly compared to placebo. Acute decreases of absolute frontal alpha (-20.4; 95%CI=-31.6,-7.47; p=.0046), beta (-15.7; 95% CI=-28.3,-0.93; p=.0390) and theta (-25.9; 95%CI=-38.4,-10.9; p=.0024) EEG parameters and of relative frontal theta power (-3.27%; 95%CI=-5.96,-0.58; p=.0187) on EEG significantly distinguished responders (n=11) from non-responders (n=32) after 6 months.

CONCLUSIONS

This study demonstrates that acute PD effects after single dose of galantamine are correlated with long-term treatment effects and that patients who demonstrate a reduction in EEG power in the alpha and theta frequency after a single administration of galantamine 16 mg will most likely respond to treatment.

Segmented Linear Mixed Model Analysis Reveals Association of the APOEɛ4 Allele with Faster Rate of Alzheimer's Disease Dementia Progression

Background:

APOEɛ4 allele carriers present with an increased risk for late-onset Alzheimer’s disease (AD), show cognitive symptoms at an earlier age, and are more likely to transition from mild cognitive impairment (MCI) to dementia but despite this, it remains unclear whether or not the ɛ4 allele controls the rate of disease progression.

Objective:

To determine the effects of the ɛ4 allele on rates of cognitive decline and brain atrophy during MCI and dementia stages of AD.

Methods:

A segmented linear mixed model was chosen for longitudinal modeling of cognitive and brain volumetric data of 73 ɛ3/ɛ3, 99 ɛ3/ɛ4, and 39 ɛ4/ɛ4 Alzheimer’s Disease Neuroimaging Initiative participants who transitioned during the study from MCI to AD dementia.

Results:

ɛ4 carriers showed faster decline on MMSE, ADAS-11, CDR-SB, and MoCA scales, with the last two measures showing significant ɛ4 allele-dose effects after dementia transition but not during MCI. The ɛ4 effect was more prevalent in younger participants and in females. ɛ4 carriers also demonstrated faster rates of atrophy of the whole brain, the hippocampus, the entorhinal cortex, the middle temporal gyrus, and expansion of the ventricles after transitioning to dementia but not during MCI.

Conclusion:

Possession of the ɛ4 allele is associated with a faster progression of dementia due to AD. Our observations support the notion that APOE genotype not only controls AD risk but also differentially regulates mechanisms of neurodegeneration underlying disease advancement. Furthermore, our findings carry significance for AD clinical trial design.

APOE4 is associated with cognitive and pathological heterogeneity in patients with Alzheimer's disease: a systematic review

Possession of the ε4 allele of apolipoprotein E (APOE) is the primary genetic risk factor for the sporadic form of Alzheimer’s disease (AD). While researchers have extensively characterized the impact that APOE ε4 (APOE4) has on the susceptibility of AD, far fewer studies have investigated the phenotypic differences of patients with AD who are APOE4 carriers vs. those who are non-carriers. In order to understand these differences, we performed a qualitative systematic literature review of the reported cognitive and pathological differences between APOE4-positive (APOE4+) vs. APOE4-negative (APOE4−) AD patients. The studies performed on this topic to date suggest that APOE4 is not only an important mediator of AD susceptibility, but that it likely confers specific phenotypic heterogeneity in AD presentation, as well. Specifically, APOE4+ AD patients appear to possess more tau accumulation and brain atrophy in the medial temporal lobe, resulting in greater memory impairment, compared to APOE4− AD patients. On the other hand, APOE4− AD patients appear to possess more tau accumulation and brain atrophy in the frontal and parietal lobes, resulting in greater impairment in executive function, visuospatial abilities, and language, compared to APOE4+ AD patients. Although more work is necessary to validate and interrogate these findings, these initial observations of pathological and cognitive heterogeneity between APOE4+ vs. APOE4− AD patients suggest that there is a fundamental divergence in AD manifestation related to APOE genotype, which may have important implications in regard to the therapeutic treatment of these two patient populations.

Suboptimal Baseline Serum Vitamin B12 Is Associated With Cognitive Decline in People With Alzheimer's Disease Undergoing Cholinesterase Inhibitor Treatment

Objectives

Cholinesterase inhibitors (ChEIs) are the mainstream treatment for delaying cognitive decline in Alzheimer’s disease (AD). Low vitamin B12 is associated with cognitive dysfunction, and its supplementation has been applied as the treatment for certain types of reversible dementia. The present study hypothesized that baseline serum vitamin B12 is associated with the deterioration of cognitive function in people with AD undergoing ChEI treatment.

Materials and methods

Between 2009 and 2016, medical records from 165 Taiwanese with mild to moderate AD who underwent ChEI treatment for at least 2 years were reviewed. Their baseline serum vitamin B12 levels were measured before treatment initiation. Their cognitive function was assessed using the Mini–Mental State Examination (MMSE) and Cognitive Abilities Screening Instrument (CASI). Student’s t test and multivariable logistic regression were used to analyze the association between cognitive decline and vitamin B12 level. Statistical analyses were performed using SPSS 19.0.

Results

Overall, 122 participants were women. Their median age was 76 years (ranging from 54 to 91). For people with optimal baseline vitamin B12 (above the median level of 436 ng/L), the rates of MMSE and CASI decline were 0.78 ± 1.28 and 2.84 ± 4.21 per year, respectively, which were significantly slower than those with suboptimal vitamin B12 (1.42 ± 1.67 and 4.94 ± 5.88 per year; p = 0.007 and 0.009, respectively). After adjustment for age, sex, education level, hypertension, diabetes, history of stroke, and baseline cognitive function, the baseline serum vitamin B12 level was negatively associated with MMSE and CASI decline.

Conclusion

Suboptimal baseline serum vitamin B12 level is associated with cognitive decline in people with AD undergoing ChEI treatment.

APOE-ɛ4 Carrier Status and Donepezil Response in Patients with Alzheimer's Disease

BACKGROUND

Previous studies have investigated associations between apolipoprotein E (APOE)-ɛ4 allele status and acetylcholinesterase inhibitor treatment response in patients with Alzheimer's disease. The ability to draw definitive conclusions regarding the effect of APOE-ɛ4 genotype on treatment response has been hindered by inconsistent results among studies and methodological limitations that restrict interpretation of study findings.

OBJECTIVE

To determine whether APOE-ɛ4 carrier status influences the magnitude of change in 13-item Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-cog) score associated with acetylcholinesterase inhibitor treatment (i.e., donepezil).

METHODS

Analyses were performed using pooled data from the donepezil and placebo treatment arms of three consecutive, similarly designed, 12-week, multi-national, randomized clinical studies that enrolled patients with mild-to-moderate Alzheimer's disease. Correlations between APOE-ɛ4 carrier status and ADAS-cog scores were evaluated using analysis of covariance.

RESULTS

No appreciable interaction between donepezil response and APOE-ɛ4 carrier status or copy number was detected. Both carriers and non-carriers of APOE-ɛ4 who received donepezil experienced significant improvements from baseline in ADAS-cog score versus placebo (p <  0.05). Change from baseline to final observation in the donepezil treatment group was - 2.95 for APOE-ɛ4 carriers and - 4.09 for non-carriers (p = 0.23). In contrast, non-carriers of APOE-ɛ4 in the placebo treatment group exhibited a greater improvement from baseline versus carriers (-2.38 versus - 0.60, p = 0.05).

CONCLUSION

Within this population, APOE genotype had no statistically significant effect on cognitive response to donepezil treatment; however, APOE-ɛ4 allele status was associated with a difference in the magnitude of the change in ADAS-cog of placebo-treated patients.

The prediction of response to galantamine treatment in patients with mild to moderate Alzheimer's disease

The prediction of efficacy in long-term treatment of acetylcholinesterase inhibitors (AChEIs) is a major clinical issue, although no consistently strong predictive factors have emerged thus far. The present analyses aimed to identify factors for predicting long-term outcome of galantamine treatment. Analyses were conducted with data from a 24 weeks randomized, double-blind, placebo controlled trial to evaluate the efficacy and the safety of galantamine in the treatment of 303 patients with mild to moderate AD. Patients were divided into responders (4 or more point improvement of ADAS-cog scores at 24 weeks of treatment) and non-responders. We explored whether patients’ background (e.g. sex, age, and duration of disease) and scores of cognitive scales at early stage, are relevant to the long-term response to AChEIs. Predictive values were estimated by the logistic regression model. The responder rate was 31.7 %. We found that changes in scores of ADAS-J cog subscales between week 4 and baseline, especially word recognition, can be a good variable to predict subsequent response to galantamine, with approximately 75% of predictive performance. Characteristics of patients, including demographic characteristics, severity of disease and neuropsychological features before treatment were poorly predictive. The present study indicate that initial response to galantamine administration in patients with mild to moderate AD seems to be a reliable predictor of response of consequent galantamine treatment. Patients who show improvement of episodic memory function during the first 4 weeks of galantamine administration may be likely to particularly benefit from galantamine treatment.

APOE interacts with age to modify rate of decline in cognitive and brain changes in Alzheimer's disease

OBJECTIVE

To determine (1) whether age-standardized cognitive declines and brain morphometric change differ between Young-Old patients with Alzheimer's disease (YOAD) and Very-Old patients with Alzheimer's disease (VOAD), and (2) whether the apolipoprotein E (APOE) genotype modifies these neuropsychological and morphometric changes.

METHODS

Baseline and 12-month follow-up neuropsychological and morphometric measures were examined for healthy control subjects and patients with AD. The two AD groups were divided further into subgroups on the basis of the presence of at least one APOE ε4 allele.

RESULTS

The YOAD group showed more severe deficits and steeper declines in cognition than the VOAD group. Moreover, the presence of an APOE ε4 allele had a more deleterious effect on the YOAD group than the VOAD group on cognition and brain structure both cross-sectionally and longitudinally.

CONCLUSIONS

Results underscore the importance of integrating an individual's age and genetic susceptibility--and their interaction--when examining neuropsychological and neuroimaging changes in the early stages of Alzheimer's disease.

Attitudes of health care professionals toward pharmacogenetic testing

BACKGROUND

Pharmacogenetics has emerged as a new tool for the optimization of drug therapy. Although the pharmacogenetics concept was first recognized at least 50 years ago, clinical testing to determine pharmacogenetic traits is still relatively rare, and many hurdles are markedly slowing its development. There is a lot of literature and speculation about potential ethical challenges in genetic and pharmacogenetic testing, yet few researchers have actually examined the attitudes of health care professionals regarding the clinical application of these tests.

OBJECTIVE

In this article, we aim to review the current literature on health care professionals' perceptions of the role of pharmacogenetic data and describe the attitudes of medical students when faced with a clinical pharmacogenetic testing scenario.

METHODS

A group of 59 third-year medical students from the American University of Beirut Medical Center were asked to answer a questionnaire about pharmacogenetic testing after being exposed to a clinical scenario of a patient who was diagnosed with mild Alzheimer Disease (AD) and hence was a candidate for therapy with one of the acetylcholinesterase (AChE) inhibitors.

RESULTS

The students indicated that they would respect patients' confidentiality and inform them about the test results and therapeutic plan, but they would not be as open about bad prognoses. They did not agree on the therapeutic plan that would follow a pharmacogenetic test result and were uncertain about potential patient discrimination in insurability.

CONCLUSION

Our and others' findings demonstrate the existence and seriousness of several challenges pertaining to pharmacogenetic applications in the clinical setting. Further training and education are needed for health care professionals, since they are the ones who will most probably request these tests in the near future.

Effect of apolipoprotein E and butyrylcholinesterase genotypes on cognitive response to cholinesterase inhibitor treatment at different stages of Alzheimer's disease

Factors that influence response to drug treatment are of increasing importance. We report an analysis of genetic factors affecting response to cholinesterase inhibitor therapy in 165 subjects with Alzheimer's disease (AD). The presence of apolipoprotein E ε4 (APOE ε4) allele was associated with early and late cognitive response to cholinesterase inhibitor treatment in mild AD (Mini-Mental State Examination (MMSE) ≥21) (P<0.01). In moderate-to-severe AD (MMSE ≤15), presence of the BCHE-K variant was associated with late response to cholinesterase inhibitor treatment (P=0.02). Testing for APOE and BCHE genotypes may be useful in therapeutic decision making.

The APOE gene and cognitive function in non-demented and Alzheimer's disease patients

This review discusses the role that the APOE gene plays in cognitive dysfunction both in demented and non-demented elderly people. The increasing problem of cognitive impairment in developed countries makes finding new and effective treatments a research priority. Understanding the biological basis of this impairment is therefore paramount. APOE has received much attention in the field of cognitive genetics due to it being a major susceptibility gene for Alzheimer's disease, which itself is characterized by a rapid and irreversible loss in memory function. Over the past 14 years this has generated a considerable number of publications that have produced conflicting findings, making it difficult for the reader to interpret whether the APOE gene regulates cognition or not. This review attempts to summarize the mass of information on this gene in relation to cognition, by weighting the pros and cons of the methodologies used, and offers suggestions for future study designs.

APOE epsilon 4 allele predicts faster cognitive decline in mild Alzheimer disease

OBJECTIVE

To determine whether APOE epsilon 4 predicts rate of cognitive change in incident and prevalent Alzheimer disease (AD).

METHODS

Individuals were recruited from two longitudinal cohort studies-the Washington Heights and Inwood Columbia Aging Project (WHICAP; population-based) and the Predictors Study (clinic-based)--and were followed for an average of 4 years. Three samples of participants diagnosed with AD, with diverse demographic characteristics and baseline cognitive functioning, were studied: 1) 199 (48%) of the incident WHICAP cases; 2) 215 (54%) of the prevalent WHICAP cases; and 3) 156 (71%) of the individuals diagnosed with AD in the Predictors Study. Generalized estimating equations were used to test whether rate of cognitive change, measured using a composite cognitive score in WHICAP and the Mini-Mental State Examination in Predictors, varied as a function of epsilon 4 status in each sample.

RESULTS

The presence of at least one epsilon 4 allele was associated with faster cognitive decline in the incident population-based AD group (p = 0.01). Parallel results were produced for the two prevalent dementia samples only when adjusting for disease severity or excluding the most impaired participants from the analyses.

CONCLUSION

APOE epsilon 4 may influence rate of cognitive decline most significantly in the earliest stages of Alzheimer disease.

Apolipoprotein E epsilon4 allele increases risk for psychotic symptoms in Alzheimer's disease

The apolipoprotein E (ApoE) epsilon4 allele is a well-documented genetic risk factor for sporadic Alzheimer's disease (AD). Its association with psychopathology among AD patients has been the subject of discrepant reports. We aimed to determine whether ApoE epsilon4+ and epsilon4- AD patients exhibit a different risk profile for psychotic symptoms and other behavioral disturbances. The Neuropsychiatric Inventory (NPI) was administered to determine the frequency and severity of psychotic and other behavioral symptoms in a sample of n=266 AD patients who had been genotyped for ApoE. Multiple logistic regression models were used to calculate the association between the ApoE epsilon4 allele and the presence of psychotic symptoms (delusions or hallucinations). Exploratory analyses were also conducted to determine the impact of disease severity on epsilon4 effects and to examine the association between epsilon4 and other behavioral symptoms. ApoE epsilon4 was significantly associated with psychotic symptoms (odds ratio (OR)=1.87, 95% CI=1.07-3.29, P=0.029), adjusting for age, sex, education, and MMSE score. More stringent definitions of clinically significant psychosis yielded similar results. Exploratory analyses suggested that this effect accrued specifically from patients with severe-stage AD and primarily from an association between epsilon4 and delusions. The epsilon4 allele did not appear to influence the development of most other behavioral symptoms in our sample. In conclusion, AD patients who carry the ApoE epsilon4 allele are at greater risk than noncarriers for developing psychotic symptoms, particularly as the severity of their dementia progresses.

Relationship Between the Efficacy of Rivastigmine and Apolipoprotein E (ε4) in Patients With Mild to Moderately Severe Alzheimer Disease

Alzheimer disease is the most common form of dementia in Western countries and the leading cause of disability in the over-65 population. Apolipoprotein E (APOE) is a multifunctional protein implied in lipid metabolism and neurobiology. Polymorphisms of the APOE gene have been associated with a variety of medical disorders, from arteriosclerosis to AD. A high frequency of the APOE epsilon4 allele has been found in patients with AD and they seem to have a higher risk of developing the disease. Various authors have suggested a possible relationship between the efficacy of cholinesterase inhibitors and the presence of the APOE epsilon4 allele. The purpose of the present study was to compare prospectively the efficacy of rivastigmine in patients with mild to moderately severe AD presenting different polymorphisms of the APOE gene on chromosome 19 and to determine if there was a difference in the response to rivastigmine treatment in AD patients with the APOE epsilon4 allele (heterozygous or homozygous) versus patients who had other forms of APOE, such as epsilon2 and epsilon3. This was an open-label, nonrandomized, multicenter study in patients over 50 years of age diagnosed with mild to moderately severe AD. The results of the analysis of this study indicate that the presence of at least one APOE epsilon4 allele does not determine a difference in the response to treatment with rivastigmine. The data indicate that knowledge of the patient's genotype is not necessary for treatment with rivastigmine. It would be interesting in the future to analyze the interaction between these 2 factors using other available anticholinesterase drugs.

Apolipoprotein E epsilon4 allele is unrelated to cognitive or functional decline in Alzheimer's disease: retrospective and prospective analysis

OBJECTIVE

The apolipoprotein E (ApoE) epsilon4 allele is a well-documented genetic risk factor for Alzheimer's disease (AD). Its role, if any, in the progression of cognitive and functional impairment in AD has been the subject of discrepant reports in the literature. This study aimed to determine whether ApoE epsilon4 dose is related to the progression of cognitive and functional decline in AD patients by combined retrospective and prospective analyses.

METHODS

A sample of 366 AD patients was genotyped for ApoE. Subjects received tests of cognition (Mini-Mental State Examination, MMSE; Alzheimer's Disease Assessment Scale-Cognitive subscale, ADAS-Cog) and daily function (Instrumental Activities of Daily Living, IADL; Alzheimer's Disease Cooperative Study-Activities of Daily Living, ADCS-ADL) at baseline and at multiple subsequent time points during their participation in a variety of research protocols. In retrospective analyses, scores on baseline cognitive and functional measures were compared cross-sectionally among genotype groups, controlling for duration of symptoms. In prospective analyses, longitudinal rates of change for each measure were computed by linear regression and compared across genotype groups.

RESULTS

No association was observed between ApoE epsilon4 dose and any of the retrospective or prospective measures of cognitive or functional decline in this AD patient sample.

CONCLUSIONS

Although ApoE epsilon4 increases the risk for AD and decreases the age of disease onset in population studies, it did not significantly influence the rate of disease progression in cognitive or functional domains in our sample.

Effect of the apolipoprotein E epsilon4 allele on the efficacy and tolerability of galantamine in the treatment of Alzheimer's disease

OBJECTIVE

To investigate the effect of the apolipoprotein E (ApoE) epsilon4 allele on the efficacy and tolerability of galantamine treatment.

METHODS

A total of 202 patients with mild to moderate Alzheimer's disease participated in a 16-week, prospective, multi-center, randomized, double-blind galantamine trial in a Korean population. Patients were assessed at baseline and after 4, 8 and 16 weeks of randomized treatment using the 11-item cognitive subscale of the Alzheimer's Disease Assessment Scale (ADAS-cog/11), the Clinician's Interview-Based Impression of Change plus Caregiver Input (CIBIC-plus), the Disability Assessment for Dementia Scale (DAD), the Behavioural Pathology in Alzheimer's Disease Rating Scale (BEHAVE-AD) and adverse events. ApoE genotypes were determined for all subjects.

RESULTS

Of the 202 subjects, 115 carried at least one ApoE epsilon4 allele and 87 did not. In both ApoE epsilon4 carriers and ApoE epsilon4 noncarriers, significant improvements were detected relative to baseline on ADAS-cog/11, CIBIC-plus, DAD and BEHAVE-AD. ApoE epsilon4 noncarriers showed better improvement in mean total BEHAVE-AD score and mean psychosis (delusions and hallucinations) subscale score than ApoE epsilon4 carriers. The incidence of weight loss was significantly higher in ApoE epsilon4 carriers (n = 11; 9.6%) than in ApoE epsilon4 noncarriers (n = 1; 1.2%) during this 16-week study, even though 92% of patients who complained of weight loss completed this 16-week trial successfully.

CONCLUSION

ApoE epsilon4 genotype does not affect galantamine-related improvements in cognition, global rating, function and behavior. Longer prospective studies with larger patient populations are required to confirm these new findings.

Apolipoprotein E epsilon4 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 epsilon4 allele is now considered a genetic risk factor for sporadic AD. There has been a growing agreement about the role exerted by the ApoE epsilon4 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 epsilon4 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 epsilon4 carriers with AD. This might suggest an early identification of AD patients carrying at least one epsilon4 allele as responders to donepezil therapy.

Medial temporal lobe atrophy and APOE genotype do not predict cognitive improvement upon treatment with rivastigmine in Alzheimer's disease patients

BACKGROUND

Only a subgroup of subjects with probable AD shows cognitive improvement after treatment with cholinesterase inhibitors.

OBJECTIVES

To investigate whether atrophy of the medial temporal lobe and the apolipoprotein E (APOE) genotype could predict cognitive improvement in subjects with probable AD treated with rivastigmine.

METHODS

121 subjects with mild to moderate probable AD were treated for 26 weeks with escalating doses of rivastigmine. Outcome measures were change on the MMSE and the ADAS-Cog between baseline and follow-up and treatment response defined as at least 2 points improvement on the MMSE or at least 4 points improvement on the ADAS-Cog. The study was an open-label multi-centre study in The Netherlands.

RESULTS

Subjects with medial temporal lobe atrophy (MTLA) tended to show more decline on the MMSE after correction for age, sex, education, baseline cognitive score, and dosage at week 26 compared with subjects without MTLA (p = 0.08). A significant interaction between MTLA and dosage at week 26 existed for change on the MMSE and ADAS-Cog: subjects with MTLA showed more cognitive decline than subjects without MTLA only in the group of patients who received a low dosage at week 26. MTLA was not associated with treatment response. The APOE genotype was not associated with change on the MMSE or ADAS-Cog or with treatment response.

CONCLUSIONS

MTLA and the APOE genotype are not clinically useful predictors of cognitive response in subjects with probable AD who are treated with rivastigmine.

Neuropsychiatric pharmacogenetics: moving toward a comprehensive understanding of predicting risks and response

Pharmacogenetic research in the area of neuropsychiatric illnesses is rapidly evolving. Due to the complexity of the human brain, it is not surprising that our knowledge about the interaction between genetics and the treatment of these illnesses is very small. The Human Genome Project (HGP) has identified > 30,000 genes; several thousand of which have been found to occur in the brain or serve a role that enhances the brain’s function. Much of the research in the post-HGP era is being driven by a desire to use genetics to predict which patients deviate from the norm in terms of drug response or side effects. By identifying these people, we will be able to direct clinical practice such that therapies for these disorders can be individualized. With this in mind, the following review is intended to cover a broad understanding of CNS pharmacogenetics with the goal of summarizing available literature on promising candidate gene targets, which may eventually help us predict clinical outcomes in patients taking medications commonly used to treat neuropsychiatric disorders.

Increased anticholinergic challenge-induced memory impairment associated with the APOE-epsilon4 allele in the elderly: a controlled pilot study

The degree to which elderly adults experience cognitive impairments from centrally acting anticholinergic drugs is variable, but the cause of this variability is unknown. The present study examined the epsilon4 allele as a possible modulator of the effects of trihexyphenidyl hydrochloride (Artane( trade mark )), an anticholinergic drug, on memory functioning. Of the 24 cognitively intact, elderly participants (age range 62-76), 12 who possessed the epsilon4 allele, participated in a double-blind, randomized, placebo-controlled, crossover, three-way study. All participants were tested after receiving a single oral dose of trihexyphenidyl (1 or 2 mg) or placebo, with a 7-day washout period between sessions. Memory and psychomotor tests were administered at baseline, and at 1, 2.5, and 5 h post-treatment. Results showed that participants with the epsilon4 allele demonstrated significant impairments in delayed recall after both 1 and 2 mg doses of trihexyphenidyl while the non-epsilon4 group did not. Additionally, while acute administration of the 2 mg dose significantly impaired total recall in both epsilon4 and non-epsilon4 carriers, the epsilon4 carriers showed a more persistent impairment. These findings held when participants with the epsilon2 allele were excluded from the analyses. The epsilon4 groups did not differ with respect to psychomotor performance or plasma drug levels. These results provide evidence suggesting that the epsilon4 allele plays a significant role in increasing cognitive sensitivity to trihexyphenidyl and that a temporal component of memory consolidation may be especially vulnerable. A larger study is warranted to confirm these preliminary findings.

Clinically tested drugs for Alzheimer's disease

Alzheimer's disease poses a major health problem in developed countries and vigorous research is underway aimed at finding effective treatments. Acetylcholinesterase inhibitors are approved but give only temporary cognitive benefit to a percentage of patients. Their relative ineffectiveness is not surprising since the neuronal loss comprises much more than the forebrain cholinergic system. What is needed is a drug that will halt the neuronal death and thus progression of the disease. Avenues being explored are aimed at pathological features of the disease, i.e., drugs aimed at removing the amyloid burden which forms the plaques or reducing the neurotoxic neuroinflammation and oxidative stress which characterise the diseased brain regions. There are some promising leads, but more definitive clinical trials are required. Any agent designed to slow progression should clearly be used at an early stage of the disorder; therefore methods of early diagnosis are also essential.

Use of artificial networks in clinical trials: a pilot study to predict responsiveness to donepezil in Alzheimer's disease

OBJECTIVES

To evaluate the accuracy of artificial neural networks compared with discriminant analysis in classifying positive and negative response to the cholinesterase inhibitor donepezil in a group of Alzheimer's disease (AD) patients.

DESIGN

Convenience sample.

SETTING

Patients with mild to moderate AD consecutively admitted to a geriatric day hospital and treated with donepezil 5 mg/day.

PARTICIPANTS

Sixty-one older patients of both sexes with AD.

MEASUREMENTS

Accuracy in detecting subjects sensitive (responders) or not (nonresponders) to 3-month therapy with ANNs. The criterion standard for evaluation of efficacy was the scores of Alzheimer's Disease Assessment Scale-Cognitive portion and Clinician's Interview Based Impression of Change-plus scales.

RESULTS

ANNs were more effective in discriminating between responders and nonresponders than other advanced statistical methods, particularly linear discriminant analysis. The total accuracy in predicting the outcome was 92.59%.

CONCLUSIONS

ANNs appear to be a useful tool in detecting patient responsiveness to pharmacological treatment in AD.

Presence or absence of at least one epsilon 4 allele and gender are not predictive for the response to donepezil treatment in Alzheimer's disease

The objective was to evaluate the effects of the apolipoprotein E (ApoE) genotype and gender on the response to donepezil treatment in Alzheimer's disease. ApoE genotyping was performed on 117 patients with mild to moderate Alzheimer's disease who were included in a 36-week open label trial of donepezil therapy. Of these 117 patients, who constituted the intent-to-treat population (ITT), 80 completed the trial, and constituted the evaluable population. Patients were treated blindly in relation to ApoE genotype. Outcome measures were Alzheimer's disease Assessment Scale-Cognitive Component (ADAS-Cog), the Mini Mental State Examination, Instrumental Activities of Daily Living, and the Caregiver-rated Clinical Global Impression of Change. ITT analysis did not reveal significant differences between the responses of epsilon 4- and epsilon 4+ carriers according to the ADAS-Cog (P = 0.28). No differences were found either between the responses of men and women (P = 0.81), and there was no significant interaction between genotype and gender (P = 0.09). Other outcome measures all exhibited similar patterns of change to those seen using the ADAS-Cog. Consequently, these results do not support the hypothesis that the ApoE phenotype and gender are predictors of the response to donepezil in Alzheimer's disease patients.

Frontiers in Neuropharmacotherapy Part I: Alzheimer’s Disease and Epilepsy

Cholinesterase inhibitors, and particularly donepezil, are the standard of care in the management of Alzheimer’s disease. Newer agents, such as rivastigmine, galantamine, and metrifonate, provide therapeutic alternatives but have advantages and disadvantages compared with donepezil. Clinical studies and continued research of the pathophysiology of Alzheimer’s disease help define the role of both the newer agents and the original cholinesterase inhibitor, tacrine. Therapies with other mechanisms of action, such as estrogen and nonsteroidal anti-inflammatory drugs (NSAIDs), are also being actively investigated for their effects on cognition. Since 1993, 8 new antiepileptic drugs have been approved by the FDA, including felbamate, gabapentin, lamotrigine, topiramate, tiagabine, and 3 recently introduced agents, oxcarbazepine, levetiracetam, and zonisamide. These second-generation agents are generally more tolerable and have fewer drug interactions than traditional antiepileptics, and some provide alternative mechanisms that may be beneficial in the management of refractory epileptic disorders. However, until clinical experience with the newer antiepileptics accumulates and well-designed comparative trials are conducted, a review of individual studies of the safety and efficacy of the newer agents helps provide the basis for treatment decisions. New information regarding traditional therapies, including new formulations and updated treatment guidelines, also assist clinicians in optimizing antiepileptic therapy.

Genetic susceptibility factors for Alzheimer's disease

Alzheimer's disease is the most frequent cause of dementia. Family and twin studies have suggested that genetic factors play a role in Alzheimer's disease development. Some Alzheimer's disease cases show an autosomal dominant inheritance pattern and thus allow the discovery of major disease genes. However, most Alzheimer's disease cases are sporadic. These cases are mainly due to the effects of several different genes and of interactions between genetic susceptibility factors and environmental factors. Such interactions are illustrated by the apolipoprotein E epsilon4 allele, associated with a higher risk of Alzheimer's disease. Other genetic susceptibility factors have been reported but variously confirmed in Alzheimer's disease: apolipoprotein E receptors, alpha2-macroglobulin or angiotensin I converting enzyme genes. Thus, except for a small percentage of Alzheimer's disease cases with a dominant inheritance pattern, the genetic component of the vast majority of cases is underlain by complex interactions of genetic susceptibility factors and environmental conditions.

Efficacy and safety of galantamine in patients with mild to moderate Alzheimer's disease: multicentre randomised controlled trial. Galantamine International-1 Study Group

OBJECTIVE

To evaluate the efficacy and safety of galantamine in the treatment of Alzheimer's disease.

DESIGN

Randomised, double blind, parallel group, placebo controlled trial.

SETTING

86 outpatient clinics in Europe and Canada.

PARTICIPANTS

653 patients with mild to moderate Alzheimer's disease.

INTERVENTION

Patients randomly assigned to galantamine had their daily dose escalated over three to four weeks to maintenance doses of 24 or 32 mg.

MAIN OUTCOME MEASURES

Scores on the 11 item cognitive subscale of the Alzheimer's disease assessment scale, the clinician's interview based impression of change plus caregiver input, and the disability assessment for dementia scale. The effect of apolipoprotein E4 genotype on reponse to treatment was also assessed.

RESULTS

At six months, patients who received galantamine had a significantly better outcome on the 11 item cognitive subscale of the Alzheimer's disease assessment scale than patients in the placebo group (mean treatment effect 2.9 points for lower dose and 3.1 for higher dose, intention to treat analysis, P<0.001 for both doses). Galantamine was more effective than placebo on the clinician's interview based impression of change plus caregiver input (P<0.05 for both doses v placebo). At six months, patients in the higher dose galantamine group had significantly better scores on the disability assessment for dementia scale than patients in the placebo group (mean treatment effect 3.4 points, P<0.05). Apolipoprotein E genotype had no effect on the efficacy of galantamine. 80% (525) of patients completed the study.

CONCLUSION

Galantamine is effective and well tolerated in Alzheimer's disease. As galantamine slowed the decline of functional ability as well as cognition, its effects are likely to be clinically relevant.

Apolipoprotein E polymorphisms and concentration in chronic diseases and drug responses

Apolipoprotein (apo) E is an important circulating and tissue protein involved in cholesterol homeostasis and many other functions. The common polymorphism in the coding region of the gene, four polymorphisms in the promoter region, other additional single nucleotide polymorphisms, as well as several apo E variants have been identified. The common coding polymorphism strongly influences the lipid metabolism and the circulating concentration of apo E itself. This polymorphism is at the origin of the implication of apo E in cardiovascular and neurodegenerative diseases, but also of the relation of apo E with longevity. Probably due to its many metabolic and functional consequences, apo E polymorphism has been shown to influence the responses of patients to several drugs (fibrates, statins, hormone replacement therapy, anti-Alzheimer drugs) or environmental interventions (black tea, alcohol, diet). Apo E genotyping may be clinically helpful in defining the risk of patients and their responses to therapeutics. Finally, circulating apo E concentration appears to be altered in diseases and can be modulated by some of the drugs cited above. This parameter can thus also give interesting clinical information and could be a therapeutic target, providing it is validated. At the present time, we cannot exclude that apo E concentration may be the most prominent apo E parameter to be considered in health and disease, while apo E polymorphisms would represent only secondary parameters influencing apo E concentration.

Galantamine in AD: A 6-month randomized, placebo-controlled trial with a 6-month extension. The Galantamine USA-1 Study Group

BACKGROUND

Galantamine is a reversible, competitive cholinesterase inhibitor that also allosterically modulates nicotinic acetylcholine receptors. These mechanisms of action provided the rationale for a therapeutic trial of galantamine in AD.

METHODS

A 6-month, multicenter, double-blind trial was undertaken in 636 patients with mild to moderate AD. Patients were randomly assigned to placebo or galantamine and escalated to maintenance doses of 24 or 32 mg/d. Eligible patients then entered a 6-month, open-label study of the 24 mg/d dose. Primary efficacy measures were the 11-item AD Assessment Scale cognitive subscale (ADAS-cog/11) and the Clinician's Interview-Based Impression of Change plus Caregiver Input (CIBIC-plus). The Disability Assessment for Dementia (DAD) scale was a secondary efficacy variable.

RESULTS

Galantamine significantly improved cognitive function relative to placebo; the treatment effects were 3.9 points (lower dose) and 3.8 points (higher dose) on the ADAS-cog/11 scale at month 6 (p < 0.001 in both cases). Both doses of galantamine produced a better outcome on CIBIC-plus than placebo (p < 0.05). Therapeutic response to galantamine was not affected by APOE genotype. At 12 months, mean ADAS-cog/11 and DAD scores had not significantly changed from baseline for patients who received galantamine 24 mg/d throughout the 12 months. The most common adverse events, which were predominantly gastrointestinal, decreased in frequency during long-term treatment. There was no evidence of hepatotoxicity.

CONCLUSIONS

Galantamine is effective and safe in AD. At 6 months, galantamine significantly improved cognition and global function. Moreover, cognitive and daily function were maintained for 12 months with the 24 mg/d dose.