Atremorine in Parkinson's disease: From dopaminergic neuroprotection to pharmacogenomics.

Atremorine is a novel bioproduct obtained by nondenaturing biotechnological processes from a genetic species of Vicia faba. Atremorine is a potent dopamine (DA) enhancer with powerful effects on the neuronal dopaminergic system, acting as a neuroprotective agent in Parkinson's disease (PD). Over 97% of PD patients respond to a single dose of Atremorine (5 g, p.o.) 1 h after administration. This response is gender-, time-, dose-, and genotype-dependent, with optimal doses ranging from 5 to 20 g/day, depending upon disease severity and concomitant medication. Drug-free patients show an increase in DA levels from 12.14 ± 0.34 pg/ml to 6463.21 ± 1306.90 pg/ml; and patients chronically treated with anti-PD drugs show an increase in DA levels from 1321.53 ± 389.94 pg/ml to 16,028.54 ± 4783.98 pg/ml, indicating that Atremorine potentiates the dopaminergic effects of conventional anti-PD drugs. Atremorine also influences the levels of other neurotransmitters (adrenaline, noradrenaline) and hormones which are regulated by DA (e.g., prolactin, PRL), with no effect on serotonin or histamine. The variability in Atremorine-induced DA response is highly attributable to pharmacogenetic factors. Polymorphic variants in pathogenic (SNCA, NUCKS1, ITGA8, GPNMB, GCH1, BCKDK, APOE, LRRK2, ACMSD), mechanistic (DRD2), metabolic (CYP2D6, CYP2C9, CYP2C19, CYP3A4/5, NAT2), transporter (ABCB1, SLC6A2, SLC6A3, SLC6A4) and pleiotropic genes (APOE) influence the DA response to Atremorine and its psychomotor and brain effects. Atremorine enhances DNA methylation and displays epigenetic activity via modulation of the pharmacoepigenetic network. Atremorine is a novel neuroprotective agent for dopaminergic neurons with potential prophylactic and therapeutic activity in PD.

Influence of Pathogenic and Metabolic Genes on the Pharmacogenetics of Mood Disorders in Alzheimer's Disease.

BACKGROUND: Mood disorders represent a risk factor for dementia and are present in over 60% of cases with Alzheimer's disease (AD). More than 80% variability in drug pharmacokinetics and pharmacodynamics is associated with pharmacogenetics. METHODS: Anxiety and depression symptoms were assessed in 1006 patients with dementia (591 females, 415 males) and the influence of pathogenic (APOE) and metabolic (CYP2D6, CYP2C19, and CYP2C9) gene variants on the therapeutic outcome were analyzed after treatment with a multifactorial regime in a natural setting. RESULTS AND CONCLUSIONS: (i) Biochemical, hematological, and metabolic differences may contribute to changes in drug efficacy and safety; (ii) anxiety and depression are more frequent and severe in females than males; (iii) both females and males respond similarly to treatment, showing significant improvements in anxiety and depression; (iv) APOE-3 carriers are the best responders and APOE-4 carriers tend to be the worst responders to conventional treatments; and (v) among CYP2D6, CYP2C19, and CYP2C9 genophenotypes, normal metabolizers (NMs) and intermediate metabolizers (IMs) are significantly better responders than poor metabolizers (PMs) and ultra-rapid metabolizers (UMs) to therapeutic interventions that modify anxiety and depression phenotypes in dementia. APOE-4 carriers and CYP-related PMs and UMs deserve special attention for their vulnerability and poor response to current treatments.

DNA Methylation in Neurodegenerative and Cerebrovascular Disorders.

DNA methylation is an epigenetic mechanism by which methyl groups are added to DNA, playing a crucial role in gene expression regulation. The aim of the present study is to compare methylation status of healthy subjects with that of patients with Alzheimer's, Parkinson's or Cerebrovascular diseases. We also analyze methylation status of a transgenic Alzheimer's disease mouse model (3xTg-AD). Our results show that both global methylation (n = 141) and hydroxymethylation (n = 131) levels are reduced in DNA samples from buffy coats of patients with neurodegenerative disorders and age-related cerebrovascular disease. The importance of methylation and hydroxymethylation reduction is stressed by the finding that DNMT3a mRNA levels are also downregulated in buffy coats of patients with Dementia (n = 25). Global methylation is also reduced in brain, liver and serum samples of 3xTg-AD vs. wild type mice, such as DNMT3a mRNA levels that are also decreased in the brain of 3xTg-AD (n = 10). These results suggest that the use of global methylation and hydroxymethylation levels, together with the study of DNMT3a expression, could be useful as a new diagnostic biomarker for these prevalent disorders.

Nutrition, Health, and Disease: Role of Selected Marine and Vegetal Nutraceuticals.

The investigation of new alternatives for disease prevention through the application of findings from dietary and food biotechnology is an ongoing challenge for the scientific community. New nutritional trends and the need to meet social and health demands have inspired the concept of functional foods and nutraceuticals which, in addition to their overall nutritional value, present certain properties for the maintenance of health. However, these effects are not universal. Nutrigenetics describes how the genetic profile has an impact on the response of the body to bioactive food components by influencing their absorption, metabolism, and site of action. The EbioSea Program, for biomarine prospection, and the Blue Butterfly Program, for the screening of vegetable-derived bioproducts, have identified a new series of nutraceuticals, devoid of side effects at conventional doses, with genotype-dependent preventive and therapeutic activity. Nutrigenomics and nutrigenetics provide the opportunity to explore the inter-individual differences in the metabolism of and response to nutrients, achieving optimal results. This fact leads to the concept of personalized nutrition as opposed to public health nutrition. Consequently, the development and prescription of nutraceuticals according to the individual genetic profile is essential to improve their effectiveness in the prevention and natural treatment of prevalent diseases.

Pharmacogenetics of Atremorine-Induced Neuroprotection and Dopamine Response in Parkinson's Disease.

Atremorine is a novel bioproduct with neuroprotective effects on dopaminergic neurons and a natural L-DOPA donor in Parkinson's disease (PD). In the present study, we show the effects of a single dose of Atremorine (5 g, p. o.) on plasma dopamine (DA) response and brain function in PD (n = 183) and the influence that pathogenic (LRRK2), metabolic (CYP2D5, CYP2C9, CYP2C19, CYP3A5, NAT2), transporter (ABCB1), pleiotropic (APOE), and detoxifying genes (CYP1B1, GSTT1, GSTP1, GSTM1, SOD2) involved in the pharmacogenetic network exerts on Atremorine-induced DA response. Over 90% of PD patients at diagnosis show plasma DA levels below 20 pg/mL. Atremorine induces DA synthesis causing a significant increase in plasma DA levels 1 h after administration in practically 100% of patients. Females tend to show lower basal DA levels than males and the response of DA to Atremorine is stronger in males than in females. Atremorine-induced DA response is pharmacogenotype-specific and lasts from 6 - 12 h depending upon the pharmacogenetic profile of each patient. Genetic variants in pathogenic genes, metabolic genes, and genes involved in the detoxification processes affect the response of DA to Atremorine in a genotype-specific manner. Atremorine or any of its bioactive components can cross the blood-brain barrier and improve brain function and motor function, as revealed by the reduction in slow wave activity in brain mapping and psychometric assessment, respectively. Atremorine is a selective neuroprotective agent for dopaminergic neurons with prophylactic and therapeutic potential in PD.

Dopaminergic Neuroprotection with Atremorine in Parkinson´s Disease.

Patients with Parkinson's disease (PD) are looking forward to new therapeutic strategies that may gradually decelerate the rate of neurodegenerative decline, associated with mobility restrictions and related morbidity. Its continuous neurodegenerative process, exacerbated by genetic mutations or environmental toxins, involves a progressive reduction in the dopamine neurotransmission levels, synaptic uptake density, oxidative glucose intake, deficient striatal lactate accumulation and chronic inflammation. Over the last decade, novel bioproducts have received considerable interest due to their unique potential of unifying nutritional, safety and therapeutic natural effects. Some nutraceuticals play a crucial role in the control of the signaling transduction pathways in neurotransmission and inflammation affected in PD, and some natural compounds can beneficially interact with each one of these biological mechanisms to slow down disease progression. Atremorine, a novel plant-derived nutraceutical, probably with a neuroprotective effect in the dopaminergic neurons of the substantia nigra (pars compacta), is a prototype of this new category of bioproducts with potential effects in PD. The major focus of this review will be on the current knowledge and biomedical investigation strategies through a plant-derived neuroprotective approach to improve life quality in PD patients, being of paramount importance for health providers, caregivers and the patients themselves.

Neuroprotective Effect of Atremorine in an Experimental Model of Parkinson's Disease.

Parkinsonian-like state was generated in mice by the administration of 1-methyl-4-phenyl-1,2,3,6- tetrahydropyridine (MPTP) to study the effects of Atremorine in Parkinson's disease (PD) related neuropathology and behavior deficits. This devastating disease is caused by the progressive degeneration of dopaminergic neurons in the substantia nigra. Numerous therapeutic strategies have been developed to protect neuronal damage, although no effective treatment for PD has been validated yet. This study tested the preventive and therapeutic neuroprotective effect of Atremorine on MPTP parkinsonian mouse model. In addition to behavioral analysis, nigrostriatal dopaminergic neurons and inflammation biomarkers were directly quantified in the affected brain regions by specific antibody-antigen-binding methods. The affected neuronal populations and behavioural alterations induced by MPTP were significantly impaired in mice when treated with Atremorine-rich diet. Differences in the Atremorine content in diet induced some degrees of neuropathological and behavior therapeutical improvement, based on the progressive beneficial effects observed in nigro-striatal dopaminergic neurons of MPTPinduced mice. Data demonstrated that Atremorine promotes neuroprotection and behavior recovery in the injured MTPT-mouse brain by modulating the expression levels of tyrosine hydroxylase, glial proteins, apoptosis and endogenous dopamine and neuromelanin concentrations, probably the key to recover the basal ganglia function.

E-MHK-0103 (Mineraxin™): A Novel Nutraceutical with Biological Properties in Menopausal Conditions.

BACKGROUND: Menopause-derived estrogen deprivation and related endocrine factors are linked to some symptoms typical of middle-aged women, such as hot flashes, aches, joint pain, stiffness, depressed mood, bone degeneration, nutritional dysfunction, or difficulty to maintain body mass. Clinical approaches to these problems often involve hormone replacement therapy and other modalities of therapeutic intervention. However, the well-known side effects associated with other pharmacological alternatives have led physicians and patients to pursue new strategies to alleviate these symptoms. As a physiological state, the first recommended option is a natural and healthy therapy, alone or in combination with pharmacotherapy in severe cases. Among other natural alternatives, E-MHK-0103, a nutraceutical lipoprotein extracted from Mytilus galloprovincialis, was found to have beneficial properties. METHODS: We reviewed numerous high-impact references to show the controversies over the current treatments used to alleviate menopausal symptoms, and presented the results obtained with E-MHK-0103 as a good natural alternative. RESULTS: E-MHK-0103 showed positive effects on hot flashes, mood swings, joint pain and bone stability, associated with its glucosamine-related anti-inflammatory effect and its high content of vitamins, minerals, iron and other substances, such as selenium and vitamin E. A significant increase in serum growth hormone, mediated by the hepatic secretion of insulin growth factor-1, and a slight decrease in bone alkaline phosphatase, calcium and ß-crosslaps concentrations contribute to its beneficial impact on bone turnover. E-MHK-0103 also showed a powerful antioxidant effect and an increase in iron stores, of particular importance in women with low basal ferritin levels. CONCLUSION: The findings of this review confirm the efficiency of natural therapies in menopause symptoms, and EMHK- 0103 as a healthy choice for inclusion into clinical practice.

Histamine and Immune Biomarkers in CNS Disorders.

Neuroimmune dysregulation is a common phenomenon in different forms of central nervous system (CNS) disorders. Cross-links between central and peripheral immune mechanisms appear to be disrupted as reflected by a series of immune markers (CD3, CD4, CD7, HLA-DR, CD25, CD28, and CD56) which show variability in brain disorders such as anxiety, depression, psychosis, stroke, Alzheimer's disease, Parkinson's disease, attention-deficit hyperactivity disorder, migraine, epilepsy, vascular dementia, mental retardation, cerebrovascular encephalopathy, multiple sclerosis, brain tumors, cranial nerve neuropathies, mental retardation, and posttraumatic brain injury. Histamine (HA) is a pleiotropic monoamine involved in several neurophysiological functions, neuroimmune regulation, and CNS pathogenesis. Changes in brain HA show an age- and sex-related pattern, and alterations in brain HA levels are present in different CNS regions of patients with Alzheimer's disease (AD). Brain HA in neuronal and nonneuronal compartments plays a dual role (neurotrophic versus neurotoxic) in a tissue-specific manner. Pathogenic mechanisms associated with neuroimmune dysregulation in AD involve HA, interleukin-1ß, and TNF-α, whose aberrant expression contributes to neuroinflammation as an aggravating factor for neurodegeneration and premature neuronal death.

Novel Therapeutic Strategies for Dementia.

Dementia represents a major problem of health and disability, with a relevant economic impact on our society. Despite important advances in pathogenesis, diagnosis and treatment, its primary causes still remain elusive, accurate biomarkers are not well characterized, and the available pharmacological treatments are not cost-effective. Alzheimer disease (AD), the most prevalent form of dementia, is a polygenic/multifactorial/complex disorder in which hundreds of defective genes distributed across the human genome may contribute to its pathogenesis. Diverse environmental factors, cerebrovascular dysfunction, and epigenetic phenomena, together with structural and functional genomic dysfunctions lead to amyloid deposition, neurofibrillary tangle formation and premature neuronal death, the major neuropathological hallmarks of AD. For the past 20 years, over 1,000 different compounds have been studied as potential candidate drugs for the treatment of AD. About 50% of these substances are novel molecules obtained from natural sources. The candidate compounds can be classified according to their pharmacological properties and/or the AD-related pathogenic cascade to which they are addressed to halt disease progression. In addition to the Food and Drug Administration (FDA)-approved drugs since 1993 (tacrine, donepezil, rivastigmine, galantamine, memantine), most candidate strategies fall into 6 major categories: (i) novel cholinesterase inhibitors and neurotransmitter regulators, (ii) anti-amyloid beta (Aß) treatments (amyloid-ß protein precursor (APP) regulators, Aß breakers, active and passive immunotherapy with vaccines and antibodies, ß - and γ - secretase inhibitors or modulators), (iii) anti-tau treatments, (iv) pleiotropic products (most of them of natural origin), (v) epigenetic intervention, and (vi) combination therapies. The implementation of pharmacogenomic strategies will contribute to optimize drug development and therapeutics in AD and related disorders.

Validating Immunotherapy in Alzheimer's Disease: The EB101 Vaccine.

Vaccination has become one of the most promising immunotherapeutic approaches in the prevention and treatment of Alzheimer's disease (AD) and related neuropathological hallmarks. Numerous immunotherapeutic interventions have attempted to achieve adaptive immunity against Aß with a range of different antigenic designs and immunomodulatory strategies, most of them with great success in AD mouse model studies. Most of these studies have shown that both active and passive immunization can drastically reduce amyloid deposition and prevent the decline in cognitive performance. New approved clinical trials are under investigation to test the effectiveness of those different vaccination approaches, although previous data showed modest clinical success with some adverse inflammatory events in immunized elderly patients. The search for new approaches to overcome these severe side effects has led to novel technical methods such as live vector or DNA vaccines, although the use of innovative adjuvants combined with selected amyloid peptides is among the most auspicious. In this review, we compare and discuss the past and contemporary vaccines and the future strategies that may lead to a viable improvement in AD prevention and treatment.

Neuroimmune Crosstalk in CNS Disorders: The Histamine Connection.

The neuroimmune system represents a dense network of biochemical signals associated with neurotransmitters, neuropeptides, neurohormones, cytokines, chemokines, and growth factors synthesized in neurons, glial cells and immune cells, to maintain systemic homeostasis. Endogenous and/or exogenous, noxious stimuli in any tissue are captured by sensor cells to inform the brain; likewise, signals originating at the central nervous system (CNS) level are transmitted to peripheral immune effectors which react to central stimuli. This multidirectional information system makes it possible for the CNS to respond to peripheral damage and for alterations in brain function to be reflected in peripheral immune changes. Different CNS disorders, such as anxiety, depression, psychosis, stroke, Alzheimer's disease, Parkinson's disease, attention-deficit hyperactivity disorder, migraine, epilepsy, vascular dementia, mental retardation, cerebrovascular encephalopathy, multiple sclerosis, brain tumors, cranial nerve neuropathies, mental retardation and post-traumatic brain injury exhibit changes in CD3, CD4, CD7, HLA-DR, CD25, CD28, and CD56 immune markers. Histamine is an important pleiotropic factor in neuroimmune regulation. This biogenic amine shows age-and sex-dependent changes in the CNS, and is significantly altered, together with interleukin- 1ß and TNF-α, in Alzheimer's disease and other neurodegenerative disorders in which neuroinflammation appears to be an aggravating phenotype. Therapeutic intervention to halt progression of deleterious neuroinflammatory reactions in CNS disorders is a major challenge for molecular pharmacology in the future.

A comparative evaluation of a novel vaccine in APP/PS1 mouse models of Alzheimer's disease.

Immunization against amyloid-beta-peptide (Aß) has been widely investigated as a potential immunotherapeutic approach for Alzheimer's disease (AD). With the aim of developing an active immunogenic vaccine without need of coadjuvant modification for human trials and therefore avoiding such side effects, we designed the Aß 1-42 vaccine (EB101), delivered in a liposomal matrix, that based on our previous studies significantly prevents and reverses the AD neuropathology, clearing Aß plaques while markedly reducing neuronal degeneration, behavioral deficits, and minimizing neuroinflammation in APP/PS1 transgenic mice. Here, the efficacy of our immunogenic vaccine EB101 was compared with the original immunization vaccine cocktail Aß 42 + CFA/IFA (Freund's adjuvant), in order to characterize the effect of sphingosine-1-phosphate (S1P) in the immunotherapeutic response. Quantitative analysis of amyloid burden showed a notable decrease in the neuroinflammation reaction against Aß plaques when S1P was compared with other treatments, suggesting that S1P plays a key role as a neuroprotective agent. Moreover, EB101 immunized mice presented a protective immunogenic reaction resulting in the increase of Aß-specific antibody response and decrease of reactive glia in the affected brain areas, leading to a Th2 immunological reaction.

Immunocytochemical characterization of Alzheimer disease hallmarks in APP/PS1 transgenic mice treated with a new anti-amyloid-ß vaccine.

APP/PS1 double-transgenic mouse models of Alzheimer's disease (AD), which overexpress mutated forms of the gene for human amyloid precursor protein (APP) and presenilin 1 (PS1), have provided robust neuropathological hallmarks of AD-like pattern at early ages. This study characterizes immunocytochemical patterns of AD mouse brain as a model for human AD treated with the EB101 vaccine. In this novel vaccine, a new approach has been taken to circumvent past failures by judiciously selecting an adjuvant consisting of a physiological matrix embedded in liposomes, composed of naturally occurring phospholipids (phosphatidylcholine, phosphatidylglycerol, and cholesterol). Our findings showed that administration of amyloid-ß1₋42 (Aß) and sphingosine-1-phosphate emulsified in liposome complex (EB101) to APP/PS1 mice before onset of Aß deposition (7 weeks of age) and/or at an older age (35 weeks of age) is effective in halting the progression and clearing the AD-like neuropathological hallmarks. Passive immunization with EB101 did not activate inflammatory responses from the immune system and astrocytes. Consistent with a decreased inflammatory background, the basal immunological interaction between the T cells and the affected areas (hippocampus) in the brain of treated mice was notably reduced. These results demonstrate that immunization with EB101 vaccine prevents and attenuates AD neuropathology in this type of double-transgenic mice.

Immunocytochemical Characterization of Alzheimer's Disease Hallmarks in APP/PS1 Transgenic Mice Treated with a New Anti-Amyloid-ß Vaccine.

INTRODUCTION: APP/PS1 double-transgenic mouse models of Alzheimer's disease (AD), which overexpress mutated forms of the gene for the human amyloid precursor protein (APP) and presenilin 1 (PS1), have provided robust neuropathological hallmarks of an AD-like pattern at early ages. This study aimed to characterize immunocytochemical patterns of the AD mouse brain, which is treated with the EB101 vaccine, as a model for human AD. MATERIAL AND METHODS: In this novel vaccine, a new approach has been taken to circumvent past failures with Aß vaccines by judiciously selecting an adjuvant consisting of a physiological matrix embedded in liposomes, composed of naturally occurring phospholipids (phosphatidylcholine, phosphatidylglycerol, and cholesterol). RESULTS: Our findings showed that the administration of amyloid-ß1-42 (Aß) and sphingosine-1-phosphate emulsified in liposome complex (EB101) to APP/PS1 mice before the onset of Aß brain deposition (at 7 weeks of age) and/or at an older age (35 weeks of age) can be effective in both halting the progression and clearing the AD-like neuropathological hallmarks. In addition, passive immunization with EB101 did not activate inflammatory responses from the immune system and astrocytes. Consistent with a decreased inflammatory background, the basal immunological interaction between the T cells and the affected areas (hippocampus) in the brain of treated mice was notably reduced. CONCLUSION: These results provide strong evidence that immunization with the EB101 vaccine prevents and attenuates AD neuropathology in this type of double-transgenic mice.

Resting-state network disruption and APOE genotype in Alzheimer's disease: a lagged functional connectivity study.

BACKGROUND: The apolipoprotein E epsilon 4 (APOE-4) is associated with a genetic vulnerability to Alzheimer's disease (AD) and with AD-related abnormalities in cortical rhythms. However, it is unclear whether APOE-4 is linked to a specific pattern of intrinsic functional disintegration of the brain after the development of the disease or during its different stages. This study aimed at identifying spatial patterns and effects of APOE genotype on resting-state oscillations and functional connectivity in patients with AD, using a physiological connectivity index called "lagged phase synchronization". METHODOLOGY/PRINCIPAL FINDINGS: Resting EEG was recorded during awake, eyes-closed state in 125 patients with AD and 60 elderly controls. Source current density and functional connectivity were determined using eLORETA. Patients with AD exhibited reduced parieto-occipital alpha oscillations compared with controls, and those carrying the APOE-4 allele had reduced alpha activity in the left inferior parietal and temporo-occipital cortex relative to noncarriers. There was a decreased alpha2 connectivity pattern in AD, involving the left temporal and bilateral parietal cortex. Several brain regions exhibited increased lagged phase synchronization in low frequencies, specifically in the theta band, across and within hemispheres, where temporal lobe connections were particularly compromised. Areas with abnormal theta connectivity correlated with cognitive scores. In patients with early AD, we found an APOE-4-related decrease in interhemispheric alpha connectivity in frontal and parieto-temporal regions. CONCLUSIONS/SIGNIFICANCE: In addition to regional cortical dysfunction, as indicated by abnormal alpha oscillations, there are patterns of functional network disruption affecting theta and alpha bands in AD that associate with the level of cognitive disturbance or with the APOE genotype. These functional patterns of nonlinear connectivity may potentially represent neurophysiological or phenotypic markers of AD, and aid in early detection of the disorder.

Vaccine Development to Treat Alzheimer's Disease Neuropathology in APP/PS1 Transgenic Mice.

A novel vaccine addressing the major hallmarks of Alzheimer's disease (AD), senile plaque-like deposits of amyloid beta-protein (Aß), neurofibrillary tangle-like structures, and glial proinflammatory cytokines, has been developed. The present vaccine takes a new approach to circumvent failures of previous ones tested in mice and humans, including the Elan-Wyeth vaccine (AN1792), which caused massive T-cell activation, resulting in a meningoencephalitis-like reaction. The EB101 vaccine consists of Aß(1-42) delivered in a novel immunogen-adjuvant composed of liposomes-containing sphingosine-1-phosphate (S1P). EB101 was administered to APPswe/PS1dE9 transgenic mice before and after AD-like pathological symptoms were detectable. Treatment with EB101 results in a marked reduction of Aß plaque burden, decrease of neurofibrillary tangle-like structure density, and attenuation of astrocytosis. In this transgenic mouse model, EB101 reduces the basal immunological interaction between the T cells and immune activation markers in the affected hippocampal/cortical areas, consistent with decreased amyloidosis-induced inflammation. Therefore, immunization with EB101 prevents and reverses AD-like neuropathology in a significant manner by halting disease progression without developing behavioral spatial deficits in transgenic mice.

Genomics of Dementia: APOE- and CYP2D6-Related Pharmacogenetics.

Dementia is a major problem of health in developed societies. Alzheimer's disease (AD), vascular dementia, and mixed dementia account for over 90% of the most prevalent forms of dementia. Both genetic and environmental factors are determinant for the phenotypic expression of dementia. AD is a complex disorder in which many different gene clusters may be involved. Most genes screened to date belong to different proteomic and metabolomic pathways potentially affecting AD pathogenesis. The ε4 variant of the APOE gene seems to be a major risk factor for both degenerative and vascular dementia. Metabolic factors, cerebrovascular disorders, and epigenetic phenomena also contribute to neurodegeneration. Five categories of genes are mainly involved in pharmacogenomics: genes associated with disease pathogenesis, genes associated with the mechanism of action of a particular drug, genes associated with phase I and phase II metabolic reactions, genes associated with transporters, and pleiotropic genes and/or genes associated with concomitant pathologies. The APOE and CYP2D6 genes have been extensively studied in AD. The therapeutic response to conventional drugs in patients with AD is genotype specific, with CYP2D6-PMs, CYP2D6-UMs, and APOE-4/4 carriers acting as the worst responders. APOE and CYP2D6 may cooperate, as pleiotropic genes, in the metabolism of drugs and hepatic function. The introduction of pharmacogenetic procedures into AD pharmacological treatment may help to optimize therapeutics.

Genomics and pharmacogenomics of brain disorders.

CNS disorders are the third major problem of health in developed countries, with approximately 10% of direct costs associated with a pharmacological treatment of doubtful cost-effectiveness. There is an alarming abuse of psychotropic drugs worldwide and only 20-30% of patients with CNS disorders appropriately respond to conventional drugs. The pathogenesis of most CNS disorders is the result of the interplay of genetic and epigenetic factors with environmental factors leading to post-transcriptional changes and proteomic and metabolomic dysfunctions. It is estimated that genetics accounts for 20% to 95% of variability in drug disposition and pharmacodynamics, and about 25-60% of the Western population is defective in genes responsible for drug metabolism. In the European population only 25% of subjects are pure extensive metabolizers for the trigenic cluster integrated by the CYP2D6, CYP2C19 and CYP2C9 genes. About 50% of adverse drug events in CNS disorders might be attributed to pharmacogenomic factors. The rationale for practical pharmacogenomics and personalized therapeutics based on individual genomic profiles implies the management of different types of genes and their products including (i) genes associated with the mechanism of action of psychotropic drugs (neurotransmitters, receptors, transporters), (ii) genes encoding enzymes responsible for drug metabolism (phase I, phase II reactions), (iii) disease-specific genes associated with a particular pathogenic cascade, and (iv) pleiotropic genes with multilocative effects in metabolomic networks. The incorporation of genomic medicine procedures and pharmacogenomics into clinical practice, together with educational programs for the correct use of medication, must help to optimize therapeutics in CNS disorders.

Pharmacogenetic aspects of therapy with cholinesterase inhibitors: the role of CYP2D6 in Alzheimer's disease pharmacogenetics.

Recent studies demonstrate that the therapeutic response in Alzheimer's disease (AD) is genotype-specific. More than 200 genes are potentially associated with AD pathogenesis and neurodegeneration, and approximately 1,400 genes distributed across the human genome account for 20 to 95% of variability in drug disposition and pharmacodynamics. Cytochrome P450 enzymes encoded by genes of the CYP superfamily, such as CYP1A1 (15q22-q24), CYP2A6 (19q13.2), CYP2C8 (10q24), CYP2C9 (10q24), CYP2C19 (10q24.1-q24.3), CYP2D6 (22q13.1), CYP2E1 (10q24.3-qter), and CYP3A5 (7q22.1), acting as terminal oxidases in multicomponent electron transfer chains which are called P450-containing monooxygenase systems, metabolize more than 90% of drugs. Some of the enzymatic products of the CYP gene superfamily can share substrates, inhibitors and inducers whereas others are quite specific for their substrates and interacting drugs. Some cholinesterase inhibitors (tacrine, donepezil, galantamine) are metabolized via CYP-related enzymes, especially CYP2D6, CYP3A4, and CYP1A2. The distribution of CYP2D6 genotypes in the Spanish population is the following: (a) Extensive Metabolizers (EM)(51.61%): *1/*1, 47.10%; and *1/*10, 4.52%; (b) Intermediate Metabolizers (IM)(32.26%): *1/*3, 1.95%; *1/*4, 17.42%; *1/*5, 3.87%; *1/*6, 2.58%; *1/*7, 0.75%; *10/*10, 1.30%; *4/*10, 3.23%; *6/*10, 0.65%; and *7/*10, 0.65%; (b) Poor Metabolizers (PM)(9.03%): *4/*4, 8.37%; and *5/*5, 0.65%; and (c) Ultrarapid Metabolizers (UM)(7.10%): *1xN/*1, 4.52%; *1xN/*4, 1.95%; and CYP2D6 gene duplications, 0.65%. PMs and UMs also accumulate genotypes of risk associated with APOE-, PS-, ACE-, and PRNP-related genes. Approximately, 15% of the AD population may exhibit an abnormal metabolism of cholinesterase inhibitors; about 50% of this population cluster would show an ultrarapid metabolism, requiring higher doses of cholinesterase inhibitors to reach a therapeutic threshold, whereas the other 50% of the cluster would exhibit a poor metabolism, displaying potential adverse events at low doses. In AD patients treated with a multifactorial therapy, including cholinesterase inhibitors (e.g., donepezil), the best responders are the CYP2D6-related EMs and IMs, and the worst responders are PMs and UMs. In addition, the presence of the APOE-4 allele in genetic clusters integrating CYP2D6 and APOE genotypes contributes to deteriorate the therapeutic outcome. From these data, it can be postulated that pharmacogenetic and pharmacogenomic factors are responsible for 75-85% of the therapeutic response in AD patients treated with conventional drugs.