Targeting mGlu Receptors for Optimization of Antipsychotic Activity and Disease-Modifying Effect in Schizophrenia

Metabotropic glutamate (mGlu) receptors are considered as candidate drug targets for the treatment of schizophrenia. These receptors form a family of eight subtypes (mGlu1 to -8), of which mGlu1 and -5 are coupled to G_q/11, and all other subtypes are coupled to G_i/o. Here, we discuss the possibility that selective ligands of individual mGlu receptor subtypes may be effective in controlling the core symptoms of schizophrenia, and, in some cases, may impact mechanisms underlying the progression of the disorder. Recent evidence indicates that activation of mGlu1 receptors inhibits dopamine release in the meso-striatal system. Hence, selective positive allosteric modulators (PAMs) of mGlu1 receptors hold promise for the treatment of positive symptoms of schizophrenia. mGlu5 receptors are widely expressed in the CNS and regulate the activity of cells that are involved in the pathophysiology of schizophrenia, such as cortical GABAergic interneurons and microglial cells. mGlu5 receptor PAMs are under development for the treatment of schizophrenia and cater the potential to act as disease modifiers by restraining neuroinflammation. mGlu2 receptors have attracted considerable interest because they negatively modulate 5-HT_2A serotonin receptor signaling in the cerebral cortex. Both mGlu2 receptor PAMs and orthosteric mGlu2/3 receptor agonists display antipsychotic-like activity in animal models, and the latter drugs are inactive in mice lacking mGlu2 receptors. So far, mGlu3 receptors have been left apart as drug targets for schizophrenia. However, activation of mGlu3 receptors boosts mGlu5 receptor signaling, supports neuronal survival, and drives microglial cells toward an antiinflammatory phenotype. This strongly encourages research of mGlu3 receptors in schizophrenia. Finally, preclical studies suggest that mGlu4 receptors might be targeted by novel antipsychotic drugs, whereas studies of mGlu7 and mGlu8 receptors in animal models of psychosis are still at their infancy.

International Union of Basic and Clinical Pharmacology CIV: The Neurobiology of Treatment-resistant Depression: From Antidepressant Classifications to Novel Pharmacological Targets

Major depressive disorder is one of the most prevalent and life-threatening forms of mental illnesses and a major cause of morbidity worldwide. Currently available antidepressants are effective for most patients, although around 30% are considered treatment resistant (TRD), a condition that is associated with a significant impairment of cognitive function and poor quality of life. In this respect, the identification of the molecular mechanisms contributing to TRD represents an essential step for the design of novel and more efficacious drugs able to modify the clinical course of this disorder and increase remission rates in clinical practice. New insights into the neurobiology of TRD have shed light on the role of a number of different mechanisms, including the glutamatergic system, immune/inflammatory systems, neurotrophin function, and epigenetics. Advances in drug discovery processes in TRD have also influenced the classification of antidepressant drugs and novel classifications are available, such as the neuroscience-based nomenclature that can incorporate such advances in drug development for TRD. This review aims to provide an up-to-date description of key mechanisms in TRD and describe current therapeutic strategies for TRD before examining novel approaches that may ultimately address important neurobiological mechanisms not targeted by currently available antidepressants. All in all, we suggest that drug targeting different neurobiological systems should be able to restore normal function but must also promote resilience to reduce the long-term vulnerability to recurrent depressive episodes.

Metabotropic Glutamate Receptors in Glial Cells: A New Potential Target for Neuroprotection?

Neurodegenerative disorders are characterized by excitotoxicity and neuroinflammation that finally lead to slow neuronal degeneration and death. Although neurons are the principal target, glial cells are important players as they contribute by either exacerbating or dampening the events that lead to neuroinflammation and neuronal damage. A dysfunction of the glutamatergic system is a common event in the pathophysiology of these diseases. Metabotropic glutamate (mGlu) receptors belong to a large family of G protein-coupled receptors largely expressed in neurons as well as in glial cells. They often appear overexpressed in areas involved in neurodegeneration, where they can modulate glutamatergic transmission. Of note, mGlu receptor upregulation may involve microglia or, even more frequently, astrocytes, where their activation causes release of factors potentially able to influence neuronal death. The expression of mGlu receptors has been also reported on oligodendrocytes, a glial cell type specifically involved in the development of multiple sclerosis. Here we will provide a general overview on the possible involvement of mGlu receptors expressed on glial cells in the pathogenesis of different neurodegenerative disorders and the potential use of subtype-selective mGlu receptor ligands as candidate drugs for the treatment of neurodegenerative disorders. Negative allosteric modulators (NAM) of mGlu5 receptors might represent a relevant pharmacological tool to develop new neuroprotective strategies in these diseases. Recent evidence suggests that targeting astrocytes and microglia with positive allosteric modulators (PAM) of mGlu3 receptor or oligodendrocytes with mGlu4 PAMS might represent novel pharmacological approaches for the treatment of neurodegenerative disorders.

Clinically Relevant Drug Interactions with Anti-Alzheimer's Drugs

BACKGROUND

The aging world population had led to an increase in the prevalence of Alzheimer's disease (AD). The drugs used to slow down the onset of AD, galantamine, donepezil, rivastigmine and memantine, are generally well-tolerated. However, drug interactions between these drugs and other drugs are an important aspect of patient safety that should be borne in mind, particularly given the high burden of polypharmacy in the elderly. The aim of this review is to provide an updated review of clinically significant drug-drug interactions concerning drugs approved for AD.

METHOD

PubMed was searched for relevant keywords. No time limit was imposed but only articles in English published in peer-reviewed journals were selected. Relevant literature was also identified from the references of identified articles. Further information was obtained from drug summary of product characteristics.

RESULTS

The major pharmacokinetic interactions identified concerned fluoxetine, paroxetine and ketoconazole when used with galantamine or donepezil. On the other hand, the major potential pharmacodynamic interactions concerned anti-dementia drugs and general anesthesia agents, anti-cholinergic drugs, conventional antipsychotics and bradycardia-inducing drugs. In clinical practice memantine shows a lower potential for pharmacodynamic drug-drug interactions (DDIs) compared to other drug classes.

CONCLUSION

The concomitant use of anti-dementia drugs with other drugs can have variable clinical effects, making appropriate prescribing of these drugs very challenging. A simple and coherent way of presenting evidence on complex drug interaction information from heterogenous sources to clinicians is needed in order for the voluminous data available to have an impact on clinical practice.

Non-toxic engineered carbon nanodiamond concentrations induce oxidative/nitrosative stress, imbalance of energy metabolism, and mitochondrial dysfunction in microglial and alveolar basal epithelial cells

Engineered nanoparticles are finding a wide spectrum of biomedical applications, including drug delivery and capacity to trigger cytotoxic phenomena, potentially useful against tumor cells. The full understanding of their biosafety and interactions with cell processes is mandatory. Using microglial (BV-2) and alveolar basal epithelial (A549) cells, in this study we determined the effects of engineered carbon nanodiamonds (ECNs) on cell viability, nitric oxide (NO) and reactive oxygen species (ROS) production, as well as on energy metabolism. Particularly, we initially measured decrease in cell viability as a function of increasing ECNs doses, finding similar cytotoxic ECN effects in the two cell lines. Subsequently, using apparently non-cytotoxic ECN concentrations (2 µg/mL causing decrease in cell number < 5%) we determined NO and ROS production, and measured the concentrations of compounds related to energy metabolism, mitochondrial functions, oxido-reductive reactions, and antioxidant defences. We found that in both cell lines non-cytotoxic ECN concentrations increased NO and ROS production with sustained oxidative/nitrosative stress, and caused energy metabolism imbalance (decrease in high energy phosphates and nicotinic coenzymes) and mitochondrial malfunctioning (decrease in ATP/ADP ratio).These results underline the importance to deeply investigate the molecular and biochemical changes occurring upon the interaction of ECNs (and nanoparticles in general) with living cells, even at apparently non-toxic concentration. Since the use of ECNs in biomedical field is attracting increasing attention the complete evaluation of their biosafety, toxicity and/or possible side effects both in vitro and in vivo is mandatory before these highly promising tools might find the correct application.

Metabotropic glutamate receptors: the potential for therapeutic applications in Alzheimer's disease

A dysfunction of glutamate signaling is implicated at several levels in the pathogenesis of Alzheimer's disease. Currently, metabotropic glutamate receptors, which have a wide distribution in the central nervous system and activate a multitude of cell signaling pathways, are pursued as targets for therapeutic intervention in Alzheimer's disease. Research is still limited, but results underscore the relevance of ongoing studies. Here we discuss the latest updates regarding metabotropic glutamate receptors and their role in Alzheimer's disease, as well as promising metabotropic glutamate receptor ligands that have been investigated in preclinical models of Alzheimer's disease.

Association of homocysteine (but not of MTHFR 677 C>T, MTR 2756 A>G, MTRR 66 A>G and TCN2 776 C>G) with ischaemic cerebrovascular disease in Sicily

Association between methylenetetrahydrofolate reductase polymorphism (MTHFR 677 C>T), a determinant of homocysteine plasma level (t-Hcys), with ischaemc cerebrovascular disease (iCVD) seems to be neutral in North Europe and North America. The association of 2756 A>G of methionine synthase (MTR), 66 A>G of methionine synthase reductase (MTRR) and 776 C>G of transcobalamin (TCN2) needs to be evaluated further. It was the objective of this study to evaluate the association of these polymorphisms, t-Hcys, vitamin B12 and folate levels with iCVD, in an Italian population from Sicily. We investigated the association of these polymorphisms, t-Hcys, vitamin B12 and folate with iCVD in 252 subjects, including 131 cases and 121 sexand agematched healthy controls. t-Hcys was higher in the iCVD group than in controls [15.3 (11.5–17.9) vs. 11.6 (9.4–14.5) µM; P=0. 0007] and also in subjects withTCN2 776CG genotype, compared to homozygous genotypes [13.5 (9.9± 16.9) vs. 11.7 (9.6 ± 14.4) µM; P=0. 0327]. The folate level in cases and controls was consistent with an adequate dietary intake [12.7 (9.0–15.3) vs. 12.5 (9.6–16.9) nM; P=0. 7203]. In multivariate analysis, t-Hcys was a significant independent predictor of iCVD with an odds ratio of 1.14 (95% C.I. : 1.06–1.24; P=0. 0006). No association was found between MTHFR, MTR, MTRR and TCN2 polymorphisms and iCVD risk. We have found an influence of t-Hcys and a neutral effect of MTHFR, MTR, MTRR and TCN2 on iCVD risk in Sicily. The neutral influence of these polymorphisms may be explained by adequate status in folate and vitamin B12. Other factors underlying the increased t-Hcys need further investigations.

Functional partnership between mGlu3 and mGlu5 metabotropic glutamate receptors in the central nervous system

mGlu5 receptors are involved in mechanisms of activity-dependent synaptic plasticity, and are targeted by drugs developed for the treatment of CNS disorders. We report that mGlu3 receptors, which are traditionally linked to the control of neurotransmitter release, support mGlu5 receptor signaling in neurons and largely contribute to the robust mGlu5 receptor-mediated polyphosphoinositide hydrolysis in the early postnatal life. In cortical pyramidal neurons, mGlu3 receptor activation potentiated mGlu5 receptor-mediated somatic Ca²⁺ mobilization, and mGlu3 receptor-mediated long-term depression in the prefrontal cortex required the endogenous activation of mGlu5 receptors. The interaction between mGlu3 and mGlu5 receptors was also relevant to mechanisms of neuronal toxicity, with mGlu3 receptors shaping the influence of mGlu5 receptors on excitotoxic neuronal death. These findings shed new light into the complex role played by mGlu receptors in physiology and pathology, and suggest reconsideration of some of the current dogmas in the mGlu receptor field.

Buspirone Counteracts MK-801-Induced Schizophrenia-Like Phenotypes through Dopamine D3 Receptor Blockade

Background: Several efforts have been made to develop effective antipsychotic drugs. Currently, available antipsychotics are effective on positive symptoms, less on negative symptoms, but not on cognitive impairment, a clinically relevant dimension of schizophrenia. Drug repurposing offers great advantages over the long-lasting, risky and expensive, de novo drug discovery strategy. To our knowledge, the possible antipsychotic properties of buspirone, an azapirone anxiolytic drug marketed in 1986 as serotonin 5-HT_1A receptor (5-HT_1AR) partial agonist, have not been extensively investigated despite its intriguing pharmacodynamic profile, which includes dopamine D₃ (D₃R) and D₄ receptor (D₄R) antagonist activity. Multiple lines of evidence point to D₃R as a valid therapeutic target for the treatment of several neuropsychiatric disorders including schizophrenia. In the present study, we tested the hypothesis that buspirone, behaving as dopamine D₃R antagonist, may have antipsychotic-like activity.

Materials and Methods: Effects of acute administration of buspirone was assessed on a wide-range of schizophrenia-relevant abnormalities induced by a single administration of the non-competitive NMDAR antagonist MK-801, in both wild-type mice (WT) and D₃R-null mutant mice (D₃R^-/-).

Results: Buspirone (3 mg⋅kg^-1, i.p.) was devoid of cataleptogenic activity in itself, but resulted effective in counteracting disruption of prepulse inhibition (PPI), hyperlocomotion and deficit of temporal order recognition memory (TOR) induced by MK-801 (0.1 mg⋅kg^-1, i.p.) in WT mice. Conversely, in D₃R^-/- mice, buspirone was ineffective in preventing MK-801-induced TOR deficit and it was only partially effective in blocking MK-801-stimulated hyperlocomotion.

Conclusion: Taken together, these results indicate, for the first time, that buspirone, might be a potential therapeutic medication for the treatment of schizophrenia. In particular, buspirone, through its D₃R antagonist activity, may be a useful tool for improving the treatment of cognitive deficits in schizophrenia that still represents an unmet need of this disease.

Topical Ocular Delivery of TGF-β1 to the Back of the Eye: Implications in Age-Related Neurodegenerative Diseases

Dysregulation of the transforming growth factor-β1 (TGF-β1)/selected small mother against decapentaplegic (SMAD) pathway can be implicated in development of age-related macular degeneration (AMD), and the delivery of TGF-β1 could be beneficial for AMD. We developed a new ophthalmic formulation of TGF-β1 assessing the ocular pharmacokinetic profile of TGF-β1 in the rabbit eye. Small unilamellar vesicles (SUV) loaded with TGF-β1 were complemented with Annexin V and Ca²⁺, and the vitreous bioavailability of TGF-β1 was assessed after topical ocular administration by a commercial ELISA kit. We detected high levels of TGF-β1 (C_max 114.7 ± 12.40 pg/mL) in the vitreous after 60 min (T_max) from the topical application of the liposomal suspension. Ocular tolerability was also assessed by a modified Draize’s test. The new formulation was well tolerated. In conclusion, we demonstrated that the novel formulation was able to deliver remarkable levels of TGF-β1 into the back of the eye after topical administration. Indeed, this TGF-β1 delivery system may be useful in clinical practice to manage ophthalmic conditions such as age-related macular degeneration, skipping invasive intraocular injections.

A new nomenclature for classifying psychotropic drugs

The Neuroscience-based Nomenclature (NbN) for psychotropic drugs was developed as an alternative to the current Anatomical Therapeutic Chemical (ATC) indication-based classification in order to provide more precise designations for this drug class. The ATC nomenclature for psychotherapeutics is limited in that it fails to specify either pharmacological domains or mechanism of action and also does not describe all the potential uses of a particular agent. The disconnect between the drug classification and its clinical use is not very useful for scientific purposes and is confusing for patients and caregivers, often leading to a misunderstanding of the intended effects of the prescribed medication and, most importantly, to low treatment adherence. The NbN classifies psychopharmacological agents on the basis of contemporary scientific information on their pharmacology and mechanisms of action so as to provide physicians clear alternatives when selecting or altering therapeutic regimens. The classification of each psychotropic drug includes four additional dimensions: approved indications; efficacy and side effects; practical note; neurobiology. By emphasizing the pharmacology and the molecular mechanism of action, NbN provides a vehicle for clinicians and basic scientists to improve the understanding and clinical use of this important drug class.

New drugs in psychiatry: focus on new pharmacological targets

The approval of psychotropic drugs with novel mechanisms of action has been rare in recent years. To address this issue, further analysis of the pathophysiology of neuropsychiatric disorders is essential for identifying new pharmacological targets for psychotropic medications. In this report, we detail drug candidates being examined as treatments for psychiatric disorders. Particular emphasis is placed on agents with novel mechanisms of action that are being tested as therapies for depression, schizophrenia, or Alzheimer’s disease. All of the compounds considered were recently approved for human use or are in advanced clinical trials. Drugs included here are new antipsychotic medications endowed with a preferential affinity at dopamine D3 receptor (cariprazine) or at glutamatergic or cannabinoid receptors, as well as vortioxetine, a drug approved for managing the cognitive deficits associated with major depression. New mechanistic approaches for the treatment of depression include intravenous ketamine or esketamine or intranasal esketamine. As for Alzheimer’s disease, the possible value of passive immunotherapy with agents such as aducanumab is considered to be a potential disease-modifying approach that could slow or halt the progressive decline associated with this devastating disorder.

Polyamine Conjugation as a Promising Strategy To Target Amyloid Aggregation in the Framework of Alzheimer's Disease

Spermine conjugates 2–6, carrying variously decorated 3,5-dibenzylidenepiperidin-4-one as bioactive motives, were designed to direct antiaggregating properties into mitochondria, using a polyamine functionality as the vehicle tool. The study confirmed mitochondrial import of the catechol derivative 2, which displayed effective antiaggregating activity and neuroprotective effects against Aβ-induced toxicity. Notably, a key functional role for the polyamine motif in Aβ molecular recognition was also unraveled. This experimental readout, which was supported by in silico studies, gives important new insight into the polyamine’s action. Hence, we propose polyamine conjugation as a promising strategy for the development of neuroprotectant leads that may contribute to decipher the complex picture of Aβ toxicity.

Silybin supplementation during HCV therapy with pegylated interferon-α plus ribavirin reduces depression and anxiety and increases work ability

BACKGROUND

Hepatitis C virus infection and interferon treatment are often associated with anxiety, depressive symptoms and poor health-related quality of life. To evaluate the Silybin-vitamin E-phospholipids complex effect on work ability and whether health related factors (anxiety and depression) were associated with work ability in subjects with chronic hepatitis C treated with Pegylated-Interferon-α2b (Peg-IFN) and Ribavirin (RBV).

METHODS

Thirty-one patients (Group A) with chronic hepatitis and other 31 subjects in Group B were recruited in a randomized, prospective, placebo controlled, double blind clinical trial. Group A received 1.5 mg/kg per week of Peg-IFN plus RBV and placebo, while Group B received the same dosage of Peg-IFN plus RBV plus association of Silybin 94 mg + vitamin E 30 mg + phospholipids 194 mg in pills for 12 months. All subjects underwent to laboratory exams and questionnaires to evaluate depression (Beck Depression Inventory - BDI), anxiety (State-trait anxiety inventory - STAI) and work ability (Work ability Index - WAI).

RESULTS

The comparison between group A and group B showed significant differences after 6 months in ALT (P < 0.001), and viremia (P < 0.05), after 12 months in ALT (P < 0.001), and AST (P < 0.001), at follow up in AST (P < 0.05), and ALT (P < 0.001). Significant difference were observed after 1 month in WAI (p < 0.001) and BDI (P < 0.05), after 6 months in WAI (P < 0.05) and STAI (P < 0.05), after 12 months and at follow up in WAI, STAI and BDI (p < 0.01).

CONCLUSIONS

The supplementation with Silybin-vitamin E -phospholipids complex increased work ability and reduced depression and anxiety in patients treated with Peg-IFN and RBV.

TRIAL REGISTRATION

NCT01957319 , First received: September 25, 2013. Last updated: September 30, 2013 (retrospectively registered).

An inflammatory and trophic disconnect biomarker profile revealed in Down syndrome plasma: Relation to cognitive decline and longitudinal evaluation

INTRODUCTION

Given that Alzheimer's pathology develops silently over decades in Down syndrome (DS), prognostic biomarkers of dementia are a major need.

METHODS

We investigated the plasma levels of Aβ, proNGF, tPA, neuroserpin, metallo-proteases and inflammatory molecules in 31 individuals with DS (with and without dementia) and in 31 healthy controls. We examined associations between biomarkers and cognitive decline.

RESULTS

Aβ40 and Aβ42 were elevated in DS plasma compared to controls, even in DS individuals without dementia. Plasma Aβ correlated with the rate of cognitive decline across 2 years. ProNGF, MMP-1, MMP-3, MMP-9 activity, TNF-α, IL-6, and IL-10 were higher in DS plasma, even at AD-asymptomatic stages. Declining plasma Aβ42 and increasing proNGF levels correlated with cognitive decline. A combined measure of Aβ and inflammatory molecules was a strong predictor of prospective cognitive deterioration.

CONCLUSIONS

Our findings support the combination of plasma and cognitive assessments for the identification of DS individuals at risk of dementia.

Fluoxetine Prevents Aβ1-42-Induced Toxicity via a Paracrine Signaling Mediated by Transforming-Growth-Factor-β1

Selective reuptake inhibitors (SSRIs), such as fluoxetine and sertraline, increase circulating Transforming-Growth-Factor-β1 (TGF-β1) levels in depressed patients, and are currently studied for their neuroprotective properties in Alzheimer’s disease. TGF-β1 is an anti-inflammatory cytokine that exerts neuroprotective effects against β-amyloid (Aβ)-induced neurodegeneration. In the present work, the SSRI, fluoxetine, was tested for the ability to protect cortical neurons against 1 μM oligomeric Aβ_1-42-induced toxicity. At therapeutic concentrations (100 nM–1 μM), fluoxetine significantly prevented Aβ-induced toxicity in mixed glia-neuronal cultures, but not in pure neuronal cultures. Though to a lesser extent, also sertraline was neuroprotective in mixed cultures, whereas serotonin (10 nM–10 μM) did not mimick fluoxetine effects. Glia-conditioned medium collected from astrocytes challenged with fluoxetine protected pure cortical neurons against Aβ toxicity. The effect was lost in the presence of a neutralizing antibody against TGF-β1 in the conditioned medium, or when the specific inhibitor of type-1 TGF-β1 receptor, SB431542, was added to pure neuronal cultures. Accordingly, a 24 h treatment of cortical astrocytes with fluoxetine promoted the release of active TGF-β1 in the culture media through the conversion of latent TGF-β1 to mature TGF-β1. Unlike fluoxetine, both serotonin and sertraline did not stimulate the astrocyte release of active TGF-β1. We conclude that fluoxetine is neuroprotective against Aβ toxicity via a paracrine signaling mediated by TGF-β1, which does not result from a simplistic SERT blockade.

The impact of metabotropic glutamate receptors into active neurodegenerative processes: A "dark side" in the development of new symptomatic treatments for neurologic and psychiatric disorders

Metabotropic glutamate (mGlu) receptor ligands are under clinical development for the treatment of CNS disorders with high social and economic burden, such as schizophrenia, major depressive disorder (MDD), and Parkinson's disease (PD), and are promising drug candidates for the treatment of Alzheimer's disease (AD). So far, clinical studies have shown symptomatic effects of mGlu receptor ligands, but it is unknown whether these drugs act as disease modifiers or, at the opposite end, they accelerate disease progression by enhancing neurodegeneration. This is a fundamental issue in the treatment of PD and AD, and is also an emerging theme in the treatment of schizophrenia and MDD, in which neurodegeneration is also present and contribute to disease progression. Moving from in vitro data and preclinical studies, we discuss the potential impact of drugs targeting mGlu2, mGlu3, mGlu4 and mGlu5 receptor ligands on active neurodegeneration associated with AD, PD, schizophrenia, and MDD. We wish to highlight that our final comments on the best drug candidates are not influenced by commercial interests or by previous or ongoing collaborations with drug companies. This article is part of the Special Issue entitled 'Metabotropic Glutamate Receptors, 5 years on'.

Italian psychiatrists' perception on cognitive symptoms in major depressive disorder

OBJECTIVE

Differently than Schizophrenia, the investigation of cognitive impairment in bipolar disorder and major depressive disorder (MDD) attracted the interest of research only recently. Therefore, it is worth understanding clinicians' perception about cognitive dysfunction in MDD and raising awareness about this issue.

METHODS

Between December 2014 and January 2015, 128 Italian psychiatrists participated in an on-line survey aiming at understanding psychiatrists' perception about cognitive symptoms in MDD. The questionnaire comprised three sections: the first investigating psychiatrists' socio-demographic profile, the second assessing cognitive symptoms relevance without mentioning that they represented the study focus and the third explicitly investigating cognitive symptoms.

RESULTS

Cognitive symptoms were considered as a relevant dimension of MDD and appeared among the most frequently cited residual symptoms influencing patients' work and relapse risk. About 70% of psychiatrists declared that cognitive symptoms significantly influence antidepressant choice. However, in the second questionnaire section cognitive symptoms appeared less frequently considered for antidepressant choice.

CONCLUSIONS

Results revealed a clear understanding of cognitive symptoms relevance in MDD. Nevertheless, the discrepancy between psychiatrists' perception and their therapeutical choices underlines the presence of an unmet-need that should be addressed increasing the awareness about the positive effects on cognitive symptoms of existing drugs, which could allow a more symptom-oriented therapeutical intervention. Key points Major depressive disorder (MDD) is a common mental disorder often associated with deficits in cognitive function. Psychiatrists considered cognitive symptoms among the most relevant residual symptoms in MDD patients that compromise patients working and influence the relapse risk. The importance given to residual cognitive symptoms seemed not to be reflected by psychiatrists' therapeutical choice. There is a gap between what psychiatrists know and what psychiatrists apply to their clinical practice reflecting the feeling of a therapeutical unmet need.

Propranolol: Effectiveness and Failure in Infantile Cutaneous Hemangiomas

Infantile hemangiomas (IHs) occur in early infancy and are considered to be one of the most frequent childhood tumors. Poor responsiveness to the treatment and complications are reported in about 10 % of patients. For years, the most common treatments for cutaneous and complicated IHs were corticosteroids, interferon-α, vincristine, laser therapy, or surgical intervention. More recently, treatment with propranolol has been reported with high success rates, both in the cutaneous and complicated form of IHs, and it is now considered to be the first-line treatment for IHs. Herein we report five cases of cutaneous IHs who presented at our unit between January 2011 and June 2012: in three of five patients, the lesion improved soon after the beginning of propranolol treatment; one case presented slow but complete resolution; and in one patient the treatment was unsuccessful. Patients who do not respond to propranolol have been seldom reported in the literature. However, the failure of propranolol treatment in childhood hemangiomas has been more frequent in our experience than that reported in previous case series. More attention should be given to the cases that poorly or negatively respond to treatment, and to the mechanisms underlying the failure to respond to treatment with propranolol.

Silybin-vitamin E-phospholipids complex reduces liver fibrosis in patients with chronic hepatitis C treated with pegylated interferon α and ribavirin

Chronic hepatitis C is both a virologic and a fibrotic disease, with mortality resulting mainly from the complications of cirrhosis and HCC. The aim was to evaluate the impact on of supplementation with a new pharmaceutical complex of silybinvitamin E-phospholipids in patients with chronic hepatitis C treated with Pegylated-Interferon-α2b plus Ribavirin. In this prospective, randomized, placebo controlled, double blind clinical trial, 32 subjects with chronic hepatitis, received Pegylated-Interferon-α2b (1.5 mg/kg per week) plus Ribavirin and placebo, while 32 subjects received the same dosage of Pegylated-Interferon-α2b plus Ribavirin plus association of Silybin 47 mg + vitamin E 15 mg + phospholipids 97 mg in two pill for 12 months. Serum levels of the following markers of liver fibrosis were evaluated: transforming growth factor beta, hyaluronic acid, metalloproteinase 2, amino-terminal pro-peptide of type III procollagen, tissue inhibitor of matrix metalloproteinase type I. The comparison between group A and group B showed a significant difference in ALT (P<0.001), and viremia (P<0.05) after 12 months; in TGF beta levels after 12 months and at follow up (P<0.05); in MMP-2 after 6 months (P<0.05); in PIIINP after 6, 12 months and at follow up (P<0.05); in TIMP-1 after 6, 12 months and at follow up (P<0.001). In conclusion, the supplementation with silybin-vitamin E-phosholipids complex ameliorated the response to Peg-IFN plus RBV treatment and reduced serum levels of markers of liver fibrosis. The ameliorative effect of the complex maybe related to a direct effect on the activation of hepatic stellate cells, or mediated via antioxidants.

The attributable burden of panic disorder in the impairment of quality of life in a national survey in Italy

INTRODUCTION/OBJECTIVE

The aim was to measure the lifetime prevalence of panic disorder (PD) in an Italian community sample, and to estimate the burden attributable to PD in compromising the quality of life (QoL) of people diagnosed with it.

METHODS

Community survey was conducted on a sample of 4,999 randomly selected adult subjects. Instruments used were semi-structured clinical interview Advanced Neuropsychiatric Tools and Assessment Schedule (ANTAS), administered by clinicians and allowing diagnosis according to Diagnostic and Statistical Manual of Mental Disorder (4th ed.; DSM-IV); Short Form Health Survey (SF-12).

RESULTS

The lifetime prevalence of PD was 3.6% (4.4% in females, 2.5% in males; p = .002). People with PD had a lower SF-12 score than the standardized community sample (35.5 ± 6.5 vs. 38.4 ± 5.9; p < .0001) with a mean difference (attributable burden) of 2.9 ± 0.7, that is, lower than PD with agoraphobia (AP; 4.2 ± 2.4). Wilson Disease (WD), Multiple Sclerosis, Major Depressive Disorder and Eating Disorders (ED) show a higher attributable burden in impaired QoL than PD, while the attributable burden of PD with AP is not lower than in ED and WD.

CONCLUSIONS

The burden attributable to the impairment of QoL following a lifetime diagnosis of PD was found to be not so great compared to the impairment caused by Major Depressive Disorder (MDD) or neurological conditions. The comorbidity of PD with AP worsens QoL significantly.

Dopamine D3 receptor-dependent changes in alpha6 GABAA subunit expression in striatum modulate anxiety-like behaviour: Responsiveness and tolerance to diazepam

Increasing evidence indicates that central dopamine (DA) neurotransmission is involved in pathophysiology of anxiety, in particular the DA receptor subtype 3 (D3R). We previously reported that D3R null mice (D3R(-/-)) exhibit low baseline anxiety levels and that acutely administrated diazepam is more effective in D3R(-/-) than in wild type (WT) when tested in the elevated plus maze test (EPM). Here we tested the hypothesis that genetic deletion or pharmacological blockade of D3R affect GABAA subunit expression, which in turn modulates anxiety-like behaviour as well as responsiveness and tolerance to diazepam. D3R(-/-) mice exhibited tolerance to diazepam (0.5mg/kg, i.p.), assessed by EPM, as fast as after 3 day-treatment, performing similarly to untreated D3R(-/-) mice; conversely, WT exhibited tolerance to diazepam after a 14-21 day-treatment. Analysis of GABAA α6 subunit mRNA expression by qPCR in striatum showed that it was about 15-fold higher in D3R(-/-) than in WT. Diazepam treatment did not modify α6 expression in D3R(-/-), but progressively increased α6 expression in WT, to the level of untreated D3R(-/-) after 14-21 day-treatment. BDNF mRNA expression in striatum was remarkably (>10-fold) increased after 3 days of diazepam-treatment in both WT and D3R(-/-); such expression level, however, slowly declined below control levels, by 14-21 days. Following a 7 day-treatment with the selective D3R antagonist SB277011A, WT exhibited a fast tolerance to diazepam accompanied by a robust increase in α6 subunit expression. In conclusion, genetic deletion or pharmacological blockade of D3R accelerate the development of tolerance to repeated administrations of diazepam and increase α6 subunit expression, a GABAA subunit that has been linked to diazepam insensitivity. Modulation of GABAA receptor by DA transmission may be involved in the mechanisms of anxiety and, if occurring in humans, may have therapeutic relevance following repeated use of drugs targeting D3R.

Does Mood Disorder Questionnaire identify sub-threshold bipolarity? Evidence studying worsening of quality of life

OBJECTIVE

It is debated whether the Mood Disorder Questionnaire (MDQ) can generate false positives by screening other disorders as bipolar, or identify sub-threshold bipolarity. The aim is to verify if Quality of Life (QoL) impairment in MQD positives in the community is due to MDQ positivity itself, or to psychiatric diagnosis associated with MDQ positivity (supporting the former hypothesis).

METHOD

Community survey. Sample randomized after stratification of the adult population in the records of seven Italian regions.

TOOLS

MDQ; Short Form Health Survey (SF-12); semi-structured clinical interview carried out by clinicians.

RESULTS

Positives at MDQ show worsening QoL with an attributable burden of 2.8 ± 1.8 lower than in MDD (5.6 ± 3.6, p < 0.001) or Eating Disorders (4.4 ± 6.6, p < 0.03) and similar to Panic Disorder (2.9 ± 0.9, p = 0.44). The burden is lower in the middle-aged (25-59 years) than in the young (18-24) (4.65 ± 4.5 vs 2.58 ± 2.0, p=0.007) or in the elderly (≥60) (4.12 ± 3.2; p = 0.024). In the elderly the burden is independent from comorbid psychiatric disorders.

LIMITATIONS

This is a preliminary study based on one survey not designed to test this specific hypothesis, thus its results have a heuristic value only.

CONCLUSIONS

The worsening of QoL due to positivity at MDQ is largely independent from comorbid conditions, supporting the hypothesis that MDQ positivity identifies a specific area of suffering that is "subthreshold" to the psychiatric diagnosis, and relevant for public health.

Folate status in type 2 diabetic patients with and without retinopathy

Background

Folate deficiency is associated with cardiovascular disease, megaloblastic anemia, and with hyperhomocysteinemia. This study has been undertaken to investigate the role of folate status during the progression of the diabetic retinopathy.

Methods

We measured the plasma levels of homocysteine, folic acid, and red cell folate in 70 diabetic type 2 patients with nonproliferative diabetic retinopathy (NPDR), 65 with proliferative diabetic retinopathy (PDR), 96 without diabetic retinopathy, and 80 healthy subjects used as a control group.

Results

We found higher plasma levels of homocysteine in the NPDR group compared to the control group (P<0.001) and in the PDR group compared to control group (P<0.001) and NPDR group (P<0.01). The severity of diabetic retinopathy was associated with lower folic acid and red cell folate levels, and a significant difference was observed between PDR and NPDR groups (P<0.05).

Conclusion

The folate status could play a role in the development and progression of diabetic retinopathy.

Monomeric ß-amyloid interacts with type-1 insulin-like growth factor receptors to provide energy supply to neurons

ß-amyloid (Aß₁₋₄₂) is produced by proteolytic cleavage of the transmembrane type-1 protein, amyloid precursor protein. Under pathological conditions, Aß₁₋₄₂self-aggregates into oligomers, which cause synaptic dysfunction and neuronal loss, and are considered the culprit of Alzheimer's disease (AD). However, Aß₁₋₄₂ is mainly monomeric at physiological concentrations, and the precise role of monomeric Aß₁₋₄₂ in neuronal function is largely unknown. We report that the monomer of Aß₁₋₄₂ activates type-1 insulin-like growth factor receptors and enhances glucose uptake in neurons and peripheral cells by promoting the translocation of the Glut3 glucose transporter from the cytosol to the plasma membrane. In neurons, activity-dependent glucose uptake was blunted after blocking endogenous Aß production, and re-established in the presence of cerebrospinal fluid Aß. APP-null neurons failed to enhance depolarization-stimulated glucose uptake unless exogenous monomeric Aß₁₋₄₂ was added. These data suggest that Aß₁₋₄₂ monomers were critical for maintaining neuronal glucose homeostasis. Accordingly, exogenous Aß₁₋₄₂ monomers were able to rescue the low levels of glucose consumption observed in brain slices from AD mutant mice.

Eating disorders as a public health issue: prevalence and attributable impairment of quality of life in an Italian community sample

The prevalence of eating disorders (ED) in the community is still under debate, as well as the measure of their impact on the well-being of individuals. It was decided to evaluate the prevalence of eating disorders in an Italian community sample as well as to measure the burden of the quality of life of people and to compare it to those attributable to other chronic illnesses. A community survey of 4,999 people using a questionnaire on health services utilization, the Advanced Neuropsychiatric Tools and Assessment Schedule (ANTAS), a semi-structured clinical interview derived from the non-patient version of the DSM-IV (SCID/NP) and Short Form Health Survey (SF-12) was conducted. A total of 3,398 individuals were interviewed (68% of those recruited). Lifetime prevalence for overall ED was 1.7%; for anorexia 0.7%; for bulimia 0.6% and for binge eating disorder 0.5%. ED was more frequent in women than in men. No cases of anorexia in men were identified. ED showed an attributable burden in impairing quality of life with no statistically significant differences with those due to major depressive disorder, bipolar spectrum disorders and Wilson's disease. Of the pathological conditions considered, only multiple sclerosis showed a worsening attributable burden. ED thus has a non-negligible frequency in Italy, with severe impact on quality of life comparable to that produced by severe chronic psychiatric and general medical conditions. These elements emphasize that ED is a serious public health issue.

Levels of the Rab GDP dissociation inhibitor (GDI) are altered in the prenatal restrain stress mouse model of schizophrenia and are differentially regulated by the mGlu2/3 receptor agonists, LY379268 and LY354740

LY379268 and LY354740, two agonists of mGlu2/3 metabotropic glutamate receptors, display different potencies in mouse models of schizophrenia. This differential effect of the two drugs remains unexplained. We performed a proteomic analysis in cultured cortical neurons challenged with either LY379268 or LY354740. Among the few proteins that were differentially influenced by the two drugs, Rab GDP dissociation inhibitor-β (Rab GDIβ) was down-regulated by LY379268 and showed a trend to an up-regulation in response to LY354740. In cultured hippocampal neurons, LY379268 selectively down-regulated the α isoform of Rab GDI. Rab GDI inhibits the activity of the synaptic vesicle-associated protein, Rab3A, and is reduced in the brain of schizophrenic patients. We examined the expression of Rab GDI in mice exposed to prenatal stress ("PRS mice"), which have been described as a putative model of schizophrenia. Rab GDIα protein levels were increased in the hippocampus of PRS mice at postnatal days (PND)1 and 21, but not at PND60. At PND21, PRS mice also showed a reduced depolarization-evoked [(3)H]d-aspartate release in hippocampal synaptosomes. The increase in Rab GDIα levels in the hippocampus of PRS mice was reversed by a 7-days treatment with LY379268 (1 or 10 mg/kg, i.p.), but not by treatment with equal doses of LY354740. These data strengthen the validity of PRS mice as a model of schizophrenia, and show for the first time a pharmacodynamic difference between LY379268 and LY354740 which might be taken into account in an attempt to explain the differential effect of the two drugs across mouse models.

Role of omega-3 fatty acids in the treatment of depressive disorders: a comprehensive meta-analysis of randomized clinical trials

Background

Despite omega-3 polyunsaturated fatty acids (PUFA) supplementation in depressed patients have been suggested to improve depressive symptomatology, previous findings are not univocal.

Objectives

To conduct an updated meta-analysis of randomized controlled trials (RCTs) of omega-3 PUFA treatment of depressive disorders, taking into account the clinical differences among patients included in the studies.

Methods

A search on MEDLINE, EMBASE, PsycInfo, and the Cochrane Database of RCTs using omega-3 PUFA on patients with depressive symptoms published up to August 2013 was performed. Standardized mean difference in clinical measure of depression severity was primary outcome. Type of omega-3 used (particularly eicosapentaenoic acid [EPA] and docosahexaenoic acid [DHA]) and omega-3 as mono- or adjuvant therapy was also examined. Meta-regression analyses assessed the effects of study size, baseline depression severity, trial duration, dose of omega-3, and age of patients.

Results

Meta-analysis of 11 and 8 trials conducted respectively on patients with a DSM-defined diagnosis of major depressive disorder (MDD) and patients with depressive symptomatology but no diagnosis of MDD demonstrated significant clinical benefit of omega-3 PUFA treatment compared to placebo (standardized difference in random-effects model 0.56 SD [95% CI: 0.20, 0.92] and 0.22 SD [95% CI: 0.01, 0.43], respectively; pooled analysis was 0.38 SD [95% CI: 0.18, 0.59]). Use of mainly EPA within the preparation, rather than DHA, influenced final clinical efficacy. Significant clinical efficacy had the use of omega-3 PUFA as adjuvant rather than mono-therapy. No relation between efficacy and study size, baseline depression severity, trial duration, age of patients, and study quality was found. Omega-3 PUFA resulted effective in RCTs on patients with bipolar disorder, whereas no evidence was found for those exploring their efficacy on depressive symptoms in young populations, perinatal depression, primary disease other than depression and healthy subjects.

Conclusions

The use of omega-3 PUFA is effective in patients with diagnosis of MDD and on depressive patients without diagnosis of MDD.

Acetyl-L-Carnitine Supplementation During HCV Therapy With Pegylated Interferon-α 2b Plus Ribavirin: Effect on Work Performance; A Randomized Clinical Trial

BACKGROUND

The health status of employees with chronic hepatitis C has major implications for organizations and labour market.

OBJECTIVES

To assess the effects of Acetyl-L-Carnitine administration on work productivity, daily activity, and fatigue in subjects with chronic hepatitis C treated with Pegylated-Interferon-α2b and Ribavirin.

PATIENTS AND METHODS

In this prospective, randomized, placebo controlled, double blind clinical trial, 30 subjects (Group A) with chronic hepatitis, received Pegylated-Interferon-α2b (1.5 mg/kg per week) plus Ribavirin and placebo, while 32 subjects (Group B) received the same dosage of Pegylated-Interferon-α2b plus Ribavirin plus 2g Acetyl-L-Carnitine twice per day, for 12 months. Work productivity loss, impairment in daily activities, presenteeism, absenteeism, have been assessed using the Work Productivity and Activity Impairment questionnaire. We also evaluated severity of fatigue, mental fatigue and physical fatigue.

RESULTS

Significant difference were observed in physical fatigue, mental fatigue and severity of fatigue, aspartate aminotransferase, alanine aminotransferase, and viremia after 12 months treatment. In Group B we observed a significant decrease of presenteeism and daily activity impairment after 6 months, 12 months and at follow up. A significant increase of work productivity was observed after 12 months and at follow up.

CONCLUSIONS

Office workers with chronic hepatitis C, treated with Pegylated-Interferon-α2b plus Ribavirin, had work performance loss. In subjects treated with Acetyl-L-Carnitine supplementation we observed increased daily activity and reduced presenteeism and fatigue. Acetyl-L-Carnitinegroup had a smaller reduction of productivity comparing to placebo group.

Homocysteine serum levels in diabetic patients with non proliferative, proliferative and without retinopathy

Homocysteine has been associated with extracellular matrix changes. The diabetic retinopathy is a neurovascular complication of diabetes mellitus and it is the leading cause of vision loss among working adults worldwide. In this study, we evaluate the role of homocysteine in diabetic retinopathy analyzing the plasma levels of homocysteine in 63 diabetic type 2 patients with nonproliferative retinopathy (NPDR), 62 patients with proliferative diabetic retinopathy (PDR), 50 healthy subjects used as control group, and 75 randomly selected patients.

Omega-3 fatty acids and depression: scientific evidence and biological mechanisms

The changing of omega-6/omega-3 polyunsaturated fatty acids (PUFA) in the food supply of Western societies occurred over the last 150 years is thought to promote the pathogenesis of many inflammatory-related diseases, including depressive disorders. Several epidemiological studies reported a significant inverse correlation between intake of oily fish and depression or bipolar disorders. Studies conducted specifically on the association between omega-3 intake and depression reported contrasting results, suggesting that the preventive role of omega-3 PUFA may depend also on other factors, such as overall diet quality and the social environment. Accordingly, tertiary prevention with omega-3 PUFA supplement in depressed patients has reached greater effectiveness during the last recent years, although definitive statements on their use in depression therapy cannot be yet freely asserted. Among the biological properties of omega-3 PUFA, their anti-inflammatory effects and their important role on the structural changing of the brain should be taken into account to better understand the possible pathway through which they can be effective both in preventing or treating depression. However, the problem of how to correct the inadequate supply of omega-3 PUFA in the Westernized countries' diet is a priority in order to set food and health policies and also dietary recommendations for individuals and population groups.

Clinical pharmacology of novel anti-Alzheimer disease modifying medications

In recent years, efforts have been directed to develop "disease-modifying" medications to treat Alzheimer's disease (AD), able to halt or slow the pathological process. Because the earlier the treatment starts, the greater is the possibility of efficacy, it is important to set up biomarkers for early diagnosis of functional brain abnormalities, before the clinical manifestation of the overt disease. Up to now, strategies to develop disease-modifying drugs have mainly targeted β amyloid (Aβ, accumulation, aggregation, clearance) and/or tau protein (phosphorylation and aggregation). Active and passive immunotherapy is the main strategy aimed at increasing Aβ clearance. Unfortunately several candidate diseasemodifying drugs have failed in phase III clinical trials conducted in mild to moderate AD. More recently, in phase III studies, bapineuzumab has been discontinued because it did not prove clinically effective (despite its significant effect on biomarkers), while solaneuzumab has been found effective in slowing AD progression. Several methological problems have been recently pointed out to explain the lack of clinical efficacy of novel disease-modifying drug-treatments; moreover, new insights in pathophysiology of AD give the premise to develop novel drug targeting. Clinical trials recently completed and/or still ongoing are discussed in the present review.

Comparing factor structure of the Mood Disorder Questionnaire (MDQ): In Italy sexual behavior is euphoric but in Asia mysterious and forbidden

BACKGROUND

The introduction of screening questionnaires, such as the Mood Disorder Questionnaire (MDQ), has stimulated clinical and epidemiological studies on bipolar disorders. In this work, we studied the item response pattern of the MDQ in the Italian population and compared the results with those of the validation of the MDQ in Asian studies (Chinese and Korean), analyzing similarities and differences among the populations studied.

METHODS

The sample was made up of 2278 participants, distributed as follows: 56.6% females, 50.8% living in the north-central Italy, and 33.7% living in rural areas. The factor analysis was run on the matrix of tetrachoric correlations. The psychometric properties of the MDQ were also studied using the Rasch logistic model.

RESULTS

The parallel analysis found two significant components. The first includes symptoms referring to acceleration, danger and irritability as risky behaviors, social interaction problems and mental flow. The second includes symptoms referring to self-confidence and energy. With respect to the Korean/Chinese results, the Italian sample, item 11 ("much more sex"), appears related to self-confidence and energy, while in Asia it is connected with items expressing risky behaviors and irritability.

LIMITATIONS

Differences in the frequency of comorbid disorders in Asian and Italian populations should be considered. The results should be confirmed and compared with those of other populations.

CONCLUSIONS

Cultural differences appear to be associated with a different symptomatic expression of bipolar spectrum disorders. Future research will investigate the role of gene-environment interaction in the genesis of these differences.

Role of the Transforming-Growth-Factor-β1 Gene in Late-Onset Alzheimer's Disease: Implications for the Treatment

Late-onset Alzheimer's disease (LOAD) is the most common form of dementia in the elderly. LOAD has a complex and largely unknown etiology with strong genetic determinants. Genetics of LOAD is known to involve several genetic risk factors among which the Apolipoprotein E (APOE) gene seems to be the major recognized genetic determinant. Recent efforts have been made to identify other genetic factors involved in the pathophysiology of LOAD such as genes associated with a deficit of neurotrophic factors in the AD brain. Genetic variations of neurotrophic factors, such as brain-derived neurotrophic factor (BDNF), and transforming-growth-factor-β1 (TGF-β1) are known to increase the risk to develop LOAD and have also been related to depression susceptibility in LOAD. Transforming-Growth-Factor-β1 (TGF-β1) is a neurotrophic factor that exerts neuroprotective effects against ß-amyloid-induced neurodegeneration. Recent evidence suggests that a specific impairment in the signaling of TGF-β is an early event in the pathogenesis of AD. TGF-β1 protein levels are predominantly under genetic control, and the TGF-β1 gene, located on chromosome 19q13.1–3, con-tains several single nucleotide polymorphisms (SNPs) upstream and in the transcript region, such as the SNP at codon +10 (T/C) and +25 (G/C), which is known to influence the level of expression of TGF-β1. In the present review, we summarize the current literature on genetic risk factors for LOAD, focusing on the role of the TGF-β1 gene, finally discussing the possible implications of these genetic studies for the selection of patients eligible for neuroprotective strategies in AD.

Pericentrin expression in Down's syndrome

Down's syndrome (DS) is the most frequent genetic cause of intellectual disability and is a chromosomal abnormality of chromosome 21 trisomy. The pericentrin gene (PCNT) has sequenced in 21q22.3 inside of the minimal critical region for Down's syndrome. Alterations of PCNT gene are associated with dwarfism, cardiomyopathy and other pathologies. In this study, we have evaluated the possible differential expression of PCNT mRNA, by qRT-PCR, in peripheral blood leukocytes of DS subjects compared with the normal population. In the present case-control study, PCNT gene expression was increased by 72.72% in 16 out 22 DS samples compared with normal subjects. Our data suggest that changes in the expression levels of PCNT in DS subjects may be involved into the molecular mechanism of Down's syndrome.

Beta-amyloid monomer and insulin/IGF-1 signaling in Alzheimer's disease

Alzheimer's disease is the most common form of dementia among older people and is still untreatable. While β-amyloid protein is recognized as the disease determinant with a pivotal role in inducing neuronal loss and dementia, an impaired brain insulin signaling seems to account in part for the cognitive deficit associated with the disease. The origin of this defective signaling is uncertain. Accumulating toxic species of β-amyloid, the so-called oligomers, has been proposed to be responsible for downregulation of neuronal insulin receptors. We have found that the nontoxic form of β-amyloid, the monomer, is able to activate insulin/insulin-like growth factor-1 (IGF-1) receptor signaling and thus behaves as a neuroprotectant agent. Our suggestion is that depletion of β-amyloid monomers, occurring in the preclinical phase of Alzheimer's disease, might be the cause of early insulin/IGF-1 signaling disturbances that anticipate cognitive decline.

New pharmacological strategies for treatment of Alzheimer's disease: focus on disease modifying drugs

Current approved drug treatments for Alzheimer disease (AD) include cholinesterase inhibitors (donepezil, rivastigmine, galantamine) and the NMDA receptor antagonist memantine. These drugs provide symptomatic relief but poorly affect the progression of the disease. Drug discovery has been directed, in the last 10 years, to develop 'disease modifying drugs' hopefully able to counteract the progression of AD. Because in a chronic, slow progressing pathological process, such as AD, an early start of treatment enhances the chance of success, it is crucial to have biomarkers for early detection of AD-related brain dysfunction, usable before clinical onset. Reliable early biomarkers need therefore to be prospectively tested for predictive accuracy, with specific cut off values validated in clinical practice. Disease modifying drugs developed so far include drugs to reduce β amyloid (Aβ) production, drugs to prevent Aβ aggregation, drugs to promote Aβ clearance, drugs targeting tau phosphorylation and assembly and other approaches. Unfortunately none of these drugs has demonstrated efficacy in phase 3 studies. The failure of clinical trials with disease modifying drugs raises a number of questions, spanning from methodological flaws to fundamental understanding of AD pathophysiology and biology. Recently, new diagnostic criteria applicable to presymptomatic stages of AD have been published. These new criteria may impact on drug development, such that future trials on disease modifying drugs will include populations susceptible to AD, before clinical onset. Specific problems with completed trials and hopes with ongoing trials are discussed in this review.