The role of dopamine in symptoms and treatment of apathy in Alzheimer's disease

Positron emission tomography measurement of brain MAO-B inhibition in patients with Alzheimer's disease and elderly controls after oral administration of sembragiline

PURPOSE

In Alzheimer's disease (AD), increased metabolism of monoamines by monoamine oxidase type B (MAO-B) leads to the production of toxic reactive oxygen species (ROS), which are thought to contribute to disease pathogenesis. Inhibition of the MAO-B enzyme may restore brain levels of monoaminergic neurotransmitters, reduce the formation of toxic ROS and reduce neuroinflammation (reactive astrocytosis), potentially leading to neuroprotection. Sembragiline (also referred as RO4602522, RG1577 and EVT 302 in previous communications) is a potent, selective and reversible inhibitor of MAO-B developed as a potential treatment for AD.

METHODS

This study assessed the relationship between plasma concentration of sembragiline and brain MAO-B inhibition in patients with AD and in healthy elderly control (EC) subjects. Positron emission tomography (PET) scans using [11C]-L-deprenyl-D2 radiotracer were performed in ten patients with AD and six EC subjects, who received sembragiline each day for 6-15 days.

RESULTS

At steady state, the relationship between sembragiline plasma concentration and MAO-B inhibition resulted in an Emax of ∼80-90 % across brain regions of interest and in an EC50 of 1-2 ng/mL. Data in patients with AD and EC subjects showed that near-maximal inhibition of brain MAO-B was achieved with 1 mg sembragiline daily, regardless of the population, whereas lower doses resulted in lower and variable brain MAO-B inhibition.

CONCLUSIONS

This PET study confirmed that daily treatment of at least 1 mg sembragiline resulted in near-maximal inhibition of brain MAO-B enzyme in patients with AD.

Role of norepinephrine in Aβ-related neurotoxicity: dual interactions with Tyr10 and SNK(26-28) of Aβ

With their capability to inhibit the formation of amyloid-β peptide (Aβ) fibril, norepinephrine (NE), and other catechol derivatives have been considered for the potential treatment of Alzheimer's disease (AD). Such treatment, however, remains debatable because of the diverse functions of Aβ and NE in AD pathology. Moreover, the complicated oxidation accompanying NE has caused the majority of the previous research to focus on the binding of NE oxides onto Aβ. The molecular mechanism by which Aβ interacts with the reduction state of NE, which is correlated with the brain function, should be urgently explored. In this work, by controlling rigorous anaerobic experimental conditions, the molecular mechanism of the Aβ/NE interaction was investigated, and two binding sites were revealed. Tyr10 was identified as the strong binding site of NE, and SNK(26-28) segment was the weak binding segment. Furthermore, thioflavin T fluorescence confirmed NE's positive function of inhibiting Aβ aggregation through its weak binding with SNK(26-28) segment. Meanwhile, 7-OHCCA fluorescence exhibited NE's negative function of enhancing ·OH generation through inhibiting the Aβ/Cu2+ coordination. The viability tests of the neuroblastoma SH-SY5Y cells displayed that the coexistence of NE, Cu2+, and Aβ induced lower cell viability than free Cu2+, indicating the significant negative effect of excessive NE on AD progression. These data revealed the possible pathway of NE-induced damage in AD brain, which is significant for understanding the function of NE in Aβ-involved AD neuropathology and for designing an NE-related therapeutic strategy for AD.

Pharmacological Therapy for Apathy in Alzheimer’s Disease: A Systematic Review and Meta-Analysis

Introduction:Apathy is highly prevalent in Alzheimer’s disease (AD), but whether pharmacotherapy is effective in managing apathy is unclear.Methods:To assess the efficacy of pharmacotherapy for apathy in AD we searched for randomized controlled trials (RCT) and aggregate data reporting on apathy in several search engines, reference lists of articles, and reviews. Demographic characteristics and relevant data were extracted to assess apathy.Results:Fifteen RCTs’ were examined, and 11 were used in aggregate meta-analytic statistics. Drugs included were cholinesterase inhibitors, memantine, and psycho-stimulants. We found no significant treatment effect in favour of any of the drugs, and the effect-size estimates under a random effect model were heterogeneous. Most RCTs had a high attrition rate and used the NPI apathy subscale to measure apathy.Conclusion:The lack of an effect could be explained by methodological limitations, publication bias, and heterogeneity.

Apathy in Dementia: Systematic Review of Recent Evidence on Pharmacological Treatments

Increasing recognition that apathy is one of the most prevalent behavioral and psychological symptoms of dementia and causes substantial caregiver distress has led to trials evaluating psychosocial and pharmacological treatments of apathy in dementia. We evaluated evidence of the efficacy of pharmacotherapies for apathy in dementia from studies since 2013. Previously reported benefits of acetylcholinesterase inhibitors and memantine were not replicated in recent studies. Antidepressants had mixed results with positive effects for apathy shown only for agomelatine, while stimulants, analgesics, and oxytocin study results were inconclusive. For some approaches, such as antipsychotic review, positive effects were found only in combination with nonpharmacological approaches. Relatively few studies assessed apathy outcomes specifically, complicating interpretation of potentially positive treatment effects; none dissected outcomes for emotional, motivational and behavioral components of apathy. Better trial design and more detailed analysis are needed in order to evaluate outcomes of pharmacological treatments for apathy.

Effect of cognitive enrichment on behavior, mucosal immunity and upper respiratory disease of shelter cats rated as frustrated on arrival

Acquisition of resources and opportunity to engage in natural behaviors has been shown to reduce frustration-related behaviors and enhance health in nondomestic felids kept in zoos, but little is known about whether there are similar effects in domestic cats living in confinement in animal shelters. Fifteen cats rated as Frustrated during the first hour of confinement to a cage at an animal shelter were assigned to either a Treatment (n=7) or Control (n=8) group. Treatment cats were taken from their cages to a separate room four times daily for 10min each time over a 10 d period, where they took part in training sessions to learn a novel behavior (paw-hand contact with a researcher). Changes in emotional states and mucosal immune response were evaluated over 10days. Infectious status was determined upon admission and incidence of upper respiratory was determined up to day 40 based on clinical signs. Treated cats were more likely to be rated as Content than Control cats and had greater concentrations of S-IgA (537μg/g) in feces than Control cats (101μg/g). Within the Treatment group, cats that responded positively had greater concentrations of S-IgA (925μg/g) than those that responded negatively (399μg/g). Control cats were more likely to develop respiratory disease over time compared to cats that received treatment (Hazard Ratio: 2.37, Confidence Interval: 1.35-4.15). It is concluded that there is prima facie evidence that cognitive enrichment of cats exhibiting frustration-related behaviors can elicit positive affect (contentment), stimulate secretion of IgA and reduce incidence of respiratory disease, which is worthy of further study.

Apathy associated with neurocognitive disorders: Recent progress and future directions

INTRODUCTION

Apathy is common in neurocognitive disorders (NCDs) such as Alzheimer's disease and mild cognitive impairment. Although the definition of apathy is inconsistent in the literature, apathy is primarily defined as a loss of motivation and decreased interest in daily activities.

METHODS

The Alzheimer's Association International Society to Advance Alzheimer's Research and Treatment (ISTAART) Neuropsychiatric Syndromes Professional Interest Area (NPS-PIA) Apathy workgroup reviewed the latest research regarding apathy in NCDs.

RESULTS

Progress has recently been made in three areas relevant to apathy: (1) phenomenology, including the use of diagnostic criteria and novel instruments for measurement, (2) neurobiology, including neuroimaging, neuropathological and biomarker correlates, and (3) interventions, including pharmacologic, nonpharmacologic, and noninvasive neuromodulatory approaches.

DISCUSSION

Recent progress confirms that apathy has a significant impact on those with major NCD and those with mild NCDs. As such, it is an important target for research and intervention.

Structure-guided development of dual β2 adrenergic/dopamine D2 receptor agonists

Aiming to discover dual-acting β2 adrenergic/dopamine D2 receptor ligands, a structure-guided approach for the evolution of GPCR agonists that address multiple targets was elaborated. Starting from GPCR crystal structures, we describe the design, synthesis and biological investigation of a defined set of compounds leading to the identification of the benzoxazinone (R)-3, which shows agonist properties at the adrenergic β2 receptor and substantial G protein-promoted activation at the D2 receptor. This directed approach yielded molecular probes with tuned dual activity. The congener desOH-3 devoid of the benzylic hydroxyl function was shown to be a β2 adrenergic antagonist/D2 receptor agonist with Ki values in the low nanomolar range. The compounds may serve as a promising starting point for the investigation and treatment of neurological disorders.

Drug Development in Alzheimer's Disease: The Contribution of PET and SPECT

Clinical trials aiming to develop disease-altering drugs for Alzheimer’s disease (AD), a neurodegenerative disorder with devastating consequences, are failing at an alarming rate. Poorly defined inclusion-and outcome criteria, due to a limited amount of objective biomarkers, is one of the major concerns. Non-invasive molecular imaging techniques, positron emission tomography and single photon emission (computed) tomography (PET and SPE(C)T), allow visualization and quantification of a wide variety of (patho)physiological processes and allow early (differential) diagnosis in many disorders. PET and SPECT have the ability to provide biomarkers that permit spatial assessment of pathophysiological molecular changes and therefore objectively evaluate and follow up therapeutic response, especially in the brain. A number of specific PET/SPECT biomarkers used in support of emerging clinical therapies in AD are discussed in this review.

Apathy in Neurodegenerative Diseases: Recommendations on the Design of Clinical Trials

Apathy is a common feature of neurodegenerative disorders but is difficult to study in a clinical trial setting due to practical and conceptual barriers. Principal challenges include a paucity of data regarding apathy in these disorders, an absence of established diagnostic criteria, the presence of confounding factors (eg, coexisting depression), use of concomitant medications, and an absence of a gold-standard apathy assessment scale. Based on a literature search and ongoing collaboration among the authors, we present recommendations for the design of future clinical trials of apathy, suggesting Alzheimer disease and Parkinson disease as models with relevance across a wider array of neuropsychiatric disorders. Recommendations address clarification of the targeted study population (apathy diagnosis and severity at baseline), confounding factors (mood/cognition, behavior, and treatment), outcome measures, study duration, use of comparators and considerations around environment, and the role of the caregiver and patient assent. This review contributes to the search for an optimal approach to study treatment of apathy in neuropsychiatric disorders.

Aripiprazole for Treatment of Apathy

OBJECTIVE

The objective of this article is to present a case of improved outcome of apathy syndrome with aripiprazole.

CASE SUMMARY

A 42-year-old man with depression and seizure disorder had significant apathy that did not respond to carbamazepine, sertraline, and topiramate. Apathy was assessed using Apathy Evaluation Scale. Discontinuation of carbamazepine did not alleviate apathy. Aripiprazole, a novel antipsychotic with partial agonistic activity at dopamine D2 receptors, was introduced and the dose adjusted to 15mg a day. The patient showed significant improvement in apathy after six weeks of therapy with aripiprazole.

DISCUSSION

Depression is often mistaken for apathy, which is different in symptoms, presentation, and treatment options. Selective serotonin reuptake inhibitors are known to cause or increase symptoms of apathy in some patients. Recent evidence suggests that dopamine receptor agonists can be helpful in treatment of apathy. Apathy significantly improved in this patient after initiation of aripiprazole.

CONCLUSION

Aripiprazole may be useful for treatment of apathy syndrome. Its role in treatment of apathy requires further investigation in clinical trials.

Localization of mutant ubiquitin in the brain of a transgenic mouse line with proteasomal inhibition and its validation at specific sites in Alzheimer's disease

Loss of protein quality control by the ubiquitin-proteasome system (UPS) during aging is one of the processes putatively contributing to cellular stress and Alzheimer's disease (AD) pathogenesis. Recently, pooled Genome Wide Association Studies (GWAS), pathway analysis and proteomics identified protein ubiquitination as one of the key modulators of AD. Mutations in ubiquitin B mRNA that result in UBB⁺¹ dose-dependently cause an impaired UPS, subsequent accumulation of UBB⁺¹ and most probably depositions of other aberrant proteins present in plaques and neurofibrillary tangles. We used specific immunohistochemical probes for a comprehensive topographic mapping of the UBB⁺¹ distribution in the brains of transgenic mouse line 3413 overexpressing UBB⁺¹. We also mapped the expression of UBB⁺¹ in brain areas of AD patients selected based upon the distribution of UBB⁺¹ in line 3413. Therefore, we focused on the olfactory bulb, basal ganglia, nucleus basalis of Meynert, inferior colliculus and raphe nuclei. UBB⁺¹ distribution was compared with established probes for pre-tangles and tangles and Aβ plaques. UBB⁺¹ distribution found in line 3413 is partly mirrored in the AD brain. Specifically, nuclei with substantial accumulations of tangle-bearing neurons, such as the nucleus basalis of Meynert and raphe nuclei also present high densities of UBB⁺¹ positive tangles. Line 3413 is useful for studying the contribution of proteasomal dysfunction in AD. The findings are consistent with evidence that areas outside the forebrain are also affected in AD. Line 3413 may also be predictive for other conformational diseases, including related tauopathies and polyglutamine diseases, in which UBB⁺¹ accumulates in their cellular hallmarks.

"Is dopamine involved in Alzheimer's disease?"

Alzheimer's Disease (AD) is a neurodegenerative disorder characterized by progressive cognitive decline and dementia. Recent advances indicate that AD pathogenesis appears more complex than its mere neuropathology. Changes in synaptic plasticity, neuronal disarray and cell death are pathways commonly recognized as pathogenic mechanisms of AD. It is thought that the altered metabolism of certain membrane proteins may lead to the production of amyloid (Aβ) oligomers that are characterized by an highly toxic effect on neurotransmission pathways, such as those mediated by Acetylcholine. The interaction of Aβ oligomers with these neurotansmitters systems would in turn induce cell dysfunction, neurotransmitters signaling imbalance and finally lead to the appearance of neurological signs. In this perspective, it is still debated how and if these mechanisms may also engage the dopaminergic system in AD. Recent experimental work revealed that the dopaminergic system may well be involved in the occurrence of cognitive decline, often being predictive of rapidly progressive forms of AD. However, a clear idea on the role of the dopamine system in AD is still missing. Here we review the more recent evidences supporting the notion that the dopaminergic dysfunction has a pathogenic role in cognitive decline symptoms of AD.

Monoaminergic neurotransmitter alterations in postmortem brain regions of depressed and aggressive patients with Alzheimer's disease

Depression and aggression in Alzheimer's disease (AD) are 2 of the most severe and prominent neuropsychiatric symptoms (NPS). Altered monoaminergic neurotransmitter system functioning has been implicated in both NPS, although their neurochemical etiology remains to be elucidated. Left frozen hemispheres of 40 neuropathologically confirmed AD patients were regionally dissected. Dichotomization based on depression and aggression scores resulted in depressed/nondepressed (AD + D/AD - D) and aggressive/nonaggressive (AD + Agr/AD - Agr) groups. Concentrations of dopamine, serotonin (5-HT), (nor)epinephrine ((N)E), and respective metabolites were determined using reversed-phase high-performance liquid chromatography. Significantly lower 3-methoxy-4-hydroxyphenylglycol (MHPG) and higher homovanillic acid levels were observed in Brodmann area (BA) 9 and 10 of AD + D compared with AD - D. In AD + Agr, 5-hydroxy-3-indoleacetic acid (5-HIAA) levels in BA9, 5-HIAA to 5-HT ratios in BA11, and MHPG, NE, and 5-HIAA levels in the hippocampus were significantly decreased compared with AD - Agr. These findings indicate that brain region-specific altered monoamines and metabolites may contribute to the occurrence of depression and aggression in AD.

Baseline neuropsychiatric symptoms and the risk of incident mild cognitive impairment: a population-based study

OBJECTIVE

The authors conducted a prospective cohort study to estimate the risk of incident mild cognitive impairment in cognitively normal elderly (aged ≥70 years) individuals with or without neuropsychiatric symptoms at baseline. The research was conducted in the setting of the population-based Mayo Clinic Study of Aging.

METHOD

A classification of normal cognitive aging, mild cognitive impairment, and dementia was adjudicated by an expert consensus panel based on published criteria. Hazard ratios and 95% confidence intervals were computed using Cox proportional hazards model, with age as a time scale. Baseline Neuropsychiatric Inventory Questionnaire data were available for 1,587 cognitively normal persons who underwent at least one follow-up visit.

RESULTS

The cohort was followed to incident mild cognitive impairment (N=365) or censoring variables (N=179) for a median of 5 years. Agitation (hazard ratio=3.06, 95% CI=1.89-4.93), apathy (hazard ratio=2.26, 95% CI=1.49-3.41), anxiety (hazard ratio=1.87, 95% CI=1.28-2.73), irritability (hazard ratio=1.84, 95% CI=1.31-2.58), and depression (hazard ratio=1.63, 95% CI=1.23-2.16), observed initially, increased risk for later mild cognitive impairment. Delusion and hallucination did not. A secondary analysis, limited in significance by the small number of study participants, showed that euphoria, disinhibition, and nighttime behaviors were significant predictors of nonamnestic mild cognitive impairment but not amnestic mild cognitive impairment. By contrast, depression predicted amnestic mild cognitive impairment (hazard ratio=1.74, 95% CI=1.22-2.47) but not nonamnestic mild cognitive impairment.

CONCLUSIONS

An increased incidence of mild cognitive impairment was observed in community-dwelling elderly adults who had nonpsychotic psychiatric symptoms at baseline. These baseline psychiatric symptoms were of similar or greater magnitude as biomarkers (genetic and structural MRI) in increasing the risk of incident mild cognitive impairment.

Negative symptoms of schizophrenia: clinical characteristics, pathophysiological substrates, experimental models and prospects for improved treatment

Schizophrenia is a complex and multifactorial disorder generally diagnosed in young adults at the time of the first psychotic episode of delusions and hallucinations. These positive symptoms can be controlled in most patients by currently-available antipsychotics. Conversely, they are poorly effective against concomitant neurocognitive dysfunction, deficits in social cognition and negative symptoms (NS), which strongly contribute to poor functional outcome. The precise notion of NS has evolved over the past century, with recent studies - underpinned by novel rating methods - suggesting two major sub-domains: "decreased emotional expression", incorporating blunted affect and poverty of speech, and "avolition", which embraces amotivation, asociality and "anhedonia" (inability to anticipate pleasure). Recent studies implicate a dysfunction of frontocortico-temporal networks in the aetiology of NS, together with a disruption of cortico-striatal circuits, though other structures are also involved, like the insular and parietal cortices, amygdala and thalamus. At the cellular level, a disruption of GABAergic-glutamatergic balance, dopaminergic signalling and, possibly, oxytocinergic and cannibinoidergic transmission may be involved. Several agents are currently under clinical investigation for the potentially improved control of NS, including oxytocin itself, N-Methyl-d-Aspartate receptor modulators and minocycline. Further, magnetic-electrical "stimulation" strategies to recruit cortical circuits and "cognitive-behavioural-psychosocial" therapies likewise hold promise. To acquire novel insights into the causes and treatment of NS, experimental study is crucial, and opportunities are emerging for improved genetic, pharmacological and developmental modelling, together with more refined readouts related to deficits in reward, sociality and "expression". The present article comprises an integrative overview of the above issues as a platform for this Special Issue of European Neuropsychopharmacology in which five clinical and five preclinical articles treat individual themes in greater detail. This Volume provides, then, a framework for progress in the understanding - and ultimately control - of the debilitating NS of schizophrenia.

Effect of methylphenidate on attention in apathetic AD patients in a randomized, placebo-controlled trial

BACKGROUND

Little is known about the effect of methylphenidate (MPH) on attention in Alzheimer's disease (AD). MPH has shown to improve apathy in AD, and both apathy and attention have been related to dopaminergic function. The goal was to investigate MPH effects on attention in AD and assess the relationship between attention and apathy responses.

METHODS

MPH (10 mg PO twice daily) or placebo was administered for six weeks in a randomized, double-blind trial in mild-to-moderate AD outpatients with apathy (Neuropsychiatric Inventory (NPI) Apathy ≥ 4). Attention was measured with the Wechsler Adult Intelligence Scale--Digit Span (DS) subtest (DS forward, selective attention) and apathy with the Apathy Evaluation Scale (AES). A mixed effects linear regression estimated the difference in change from baseline between treatment groups, defined as δ (MPH (DS week 6-DS baseline)) - (placebo (DS week 6-DS baseline)).

RESULTS

In 60 patients (37 females, age = 76 ± 8, Mini-Mental State Examination (MMSE) = 20 ± 5, NPI Apathy = 7 ± 2), the change in DS forward (δ = 0.87 (95% CI: 0.06-1.68), p = 0.03) and DS total (δ = 1.01 (95% CI: 0.09-1.93), p = 0.03) favored MPH over placebo. Of 57 completers, 17 patients had improved apathy (≥3.3 points on the AES from baseline to end point) and 40 did not. There were no significant associations between AES and NPI Apathy with DS change scores in the MPH, placebo, AES responder, or non-responder groups. DS scores did not predict apathy response to MPH treatment.

CONCLUSION

These results suggest MPH can improve attention and apathy in AD; however, the effects appear independent in this population.

Behavioral symptoms related to cognitive impairment

Neuropsychiatric symptoms (NPS) are core features of Alzheimer's disease and related dementias. On one hand, behavioral symptoms in patients with mild cognitive impairment (MCI) can indicate an increased risk of progressing to dementia. On the other hand, mild behavioral impairment (MBI) in patients who usually have normal cognition indicates an increased risk of developing dementia. Whatever the cause, all dementias carry a high rate of NPI. These symptoms can be observed at any stage of the disease, may fluctuate over its course, are a leading cause of stress and overload for caregivers, and increase rates of hospitalization and early institutionalization for patients with dementia. The clinician should be able to promptly recognize NPI through the use of instruments capable of measuring their frequency and severity to support diagnosis, and to help monitor the treatment of behavioral symptoms. The aims of this review are to describe and update the construct 'MBI' and to revise the reported NPS related to prodromal stages of dementia (MCI and MBI) and dementia stages of Alzheimer's disease and frontotemporal lobar degeneration.

Safety and efficacy of methylphenidate for apathy in Alzheimer's disease: a randomized, placebo-controlled trial

OBJECTIVE

In a recent crossover trial, methylphenidate treatment decreased apathy in Alzheimer's disease. We further assessed this finding in the Apathy in Dementia Methylphenidate Trial (ADMET).

METHOD

Six-week, randomized, double-blind, placebo-controlled multicenter trial enrolling Alzheimer's disease participants (NINCDS-ADRDA criteria) with apathy assigned to methylphenidate 20 mg daily or placebo, conducted from June 2010 to December 2011. Primary outcomes were change in Apathy Evaluation Scale (AES) score and modified Alzheimer's Disease Cooperative Study-Clinical Global Impression of Change (ADCS-CGI-C). Secondary outcomes included change in Neuropsychiatric Inventory (NPI) apathy score, Mini-Mental State Examination (MMSE) score, and safety.

RESULTS

60 participants were randomly assigned (29 methylphenidate, 31 placebo). At baseline, mean (SD) age = 76 (8) years, MMSE score = 20 (5), AES score = 51 (12), NPI total score = 16 (8), and 62% of the participants (n = 37) were female. After 6 weeks' treatment, mean (SD) change in AES score was -1.9 (1.5) for methylphenidate and 0.6 (1.4) for placebo (P = .23). Odds ratio for improvement in ADCS-CGI-C was 3.7 (95% CI, 1.3 to 10.8) (P = .02), with 21% of methylphenidate versus 3% of placebo rated as moderately or markedly improved. NPI apathy score improvement was 1.8 points (95% CI, 0.3 to 3.4) greater on methylphenidate than on placebo (P = .02). MMSE trended toward improvement on methylphenidate (P = .06). There were trends toward greater anxiety and weight loss > 2% in the methylphenidate-treated group.

CONCLUSIONS

Methylphenidate treatment of apathy in Alzheimer's disease was associated with significant improvement in 2 of 3 efficacy outcomes and a trend toward improved global cognition with minimal adverse events, supporting the safety and efficacy of methylphenidate treatment for apathy in Alzheimer's disease.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT01117181.

Ascending monoaminergic systems alterations in Alzheimer's disease. translating basic science into clinical care

Extensive neuropathological studies have established a compelling link between abnormalities in structure and function of subcortical monoaminergic (MA-ergic) systems and the pathophysiology of Alzheimer's disease (AD). The main cell populations of these systems including the locus coeruleus, the raphe nuclei, and the tuberomamillary nucleus undergo significant degeneration in AD, thereby depriving the hippocampal and cortical neurons from their critical modulatory influence. These studies have been complemented by genome wide association studies linking polymorphisms in key genes involved in the MA-ergic systems and particular behavioral abnormalities in AD. Importantly, several recent studies have shown that improvement of the MA-ergic systems can both restore cognitive function and reduce AD-related pathology in animal models of neurodegeneration. This review aims to explore the link between abnormalities in the MA-ergic systems and AD symptomatology as well as the therapeutic strategies targeting these systems. Furthermore, we will examine possible mechanisms behind basic vulnerability of MA-ergic neurons in AD.

NMDA Neurotransmission Dysfunction in Behavioral and Psychological Symptoms of Alzheimer's Disease

Dementia has become an all-important disease because the population is aging rapidly and the cost of health care associated with dementia is ever increasing. In addition to cognitive function impairment, associated behavioral and psychological symptoms of dementia (BPSD) worsen patient’s quality of life and increase caregiver’s burden. Alzheimer’s disease is the most common type of dementia and both behavioral disturbance and cognitive impairment of Alzheimer’s disease are thought to be associated with the N-methyl-D-aspartate (NMDA) dysfunction as increasing evidence of dysfunctional glutamatergic neurotransmission had been reported in behavioral changes and cognitive decline in Alzheimer’s disease. We review the literature regarding dementia (especially Alzheimer’s disease), BPSD and relevant findings on glutamatergic and NMDA neurotransmission, including the effects of memantine, a NMDA receptor antagonist, and NMDA-enhancing agents, such as D-serine and D-cycloserine. Literatures suggest that behavioral disturbance and cognitive impairment of Alzheimer’s disease may be associated with excitatory neurotoxic effects which result in impairment of neuronal plasticity and degenerative processes. Memantine shows benefits in improving cognition, function, agitation/aggression and delusion in Alzheimer’s disease. On the other hand, some NMDA modulators which enhance NMDA function through the co-agonist binding site can also improve cognitive function and psychotic symptoms. We propose that modulating NMDA neurotransmission is effective in treating behavioral and psychological symptoms of Alzheimer’s disease. Prospective study using NMDA enhancers in patients with Alzheimer’s disease and associated behavioral disturbance is needed to verify this hypothesis.

Restless legs syndrome in a group of patients with Alzheimer's disease

BACKGROUND

Restless legs syndrome (RLS) is a neurological disorder characterized by the urge to move the legs associated with peculiar unpleasant sensations during periods of rest and inactivity that are relieved by movement. A few studies analyzed RLS in neurodegenerative diseases such as Alzheimer's Disease (AD). The aim of our study was to assess the prevalence and the clinical characteristics of RLS in a cohort of AD patients.

METHODS

Three hundred and thirty-nine subjects with a diagnosis of AD were recruited. Cognitive, functional, and neuropsychiatric measures were collected at baseline and six-monthly for a 2-years follow-up

RESULTS

Fourteen subjects met the RLS criteria. RLS subjects were more frequently male (p:0,006) and younger than AD subject without RLS (p:0,029). MMSE, ADL and IADL were not significantly different. NPI total scores did not differ significantly, however, AD patients with RLS were found to be more apathetic (p:0,001) than AD subjects without RLS.

CONCLUSION

RLS prevalence in our AD cohort was estimated to be about 4%. RLS appeared to be associated with neuropsychiatric symptoms such as apathy. RLS and apathy might share a common pathophysiological basis represented by a dysfunction of the central dopaminergic system.

Neuropsychiatric symptoms in Alzheimer's disease

Neuropsychiatric symptoms (NPS) are core features of Alzheimer's disease and related dementias. Once thought to emerge primarily in people with late-stage disease, these symptoms are currently known to manifest commonly in very early disease and in prodromal phases, such as mild cognitive impairment. Despite decades of research, reliable treatments for dementia-associated NPS have not been found, and those that are in widespread use present notable risks for people using these medications. An Alzheimer's Association Research Roundtable was convened in the spring of 2010 to review what is known about NPS in Alzheimer's disease, to discuss classification and underlying neuropathogenesis and vulnerabilities, and to formulate recommendations for new approaches to tailored therapeutics.

Neuropsychiatric symptoms in Alzheimer's disease

Neuropsychiatric symptoms (NPS) are core features of Alzheimer's disease and related dementias. Once thought to emerge primarily in people with late-stage disease, these symptoms are currently known to manifest commonly in very early disease and in prodromal phases, such as mild cognitive impairment. Despite decades of research, reliable treatments for dementia-associated NPS have not been found, and those that are in widespread use present notable risks for people using these medications. An Alzheimer's Association Research Roundtable was convened in the spring of 2010 to review what is known about NPS in Alzheimer's disease, to discuss classification and underlying neuropathogenesis and vulnerabilities, and to formulate recommendations for new approaches to tailored therapeutics.

Behavioral and psychological symptoms of dementia

Behavioral and psychological symptoms of dementia (BPSD), also known as neuropsychiatric symptoms, represent a heterogeneous group of non-cognitive symptoms and behaviors occurring in subjects with dementia. BPSD constitute a major component of the dementia syndrome irrespective of its subtype. They are as clinically relevant as cognitive symptoms as they strongly correlate with the degree of functional and cognitive impairment. BPSD include agitation, aberrant motor behavior, anxiety, elation, irritability, depression, apathy, disinhibition, delusions, hallucinations, and sleep or appetite changes. It is estimated that BPSD affect up to 90% of all dementia subjects over the course of their illness, and is independently associated with poor outcomes, including distress among patients and caregivers, long-term hospitalization, misuse of medication, and increased health care costs. Although these symptoms can be present individually it is more common that various psychopathological features co-occur simultaneously in the same patient. Thus, categorization of BPSD in clusters taking into account their natural course, prognosis, and treatment response may be useful in the clinical practice. The pathogenesis of BPSD has not been clearly delineated but it is probably the result of a complex interplay of psychological, social, and biological factors. Recent studies have emphasized the role of neurochemical, neuropathological, and genetic factors underlying the clinical manifestations of BPSD. A high degree of clinical expertise is crucial to appropriately recognize and manage the neuropsychiatric symptoms in a patient with dementia. Combination of non-pharmacological and careful use of pharmacological interventions is the recommended therapeutic for managing BPSD. Given the modest efficacy of current strategies, there is an urgent need to identify novel pharmacological targets and develop new non-pharmacological approaches to improve the adverse outcomes associated with BPSD.

Predictors of performance monitoring abilities following traumatic brain injury: the influence of negative affect and cognitive sequelae

Performance monitoring is a cognitive control process modulated by both cognitive and affective variables. This study examined the relative contributions of negative affect (NA) and cognitive sequelae to performance monitoring dysfunction following severe traumatic brain injury (TBI). We used the error-related negativity (ERN) and post-error positivity (Pe) components of the event-related potential (ERP) to test the hypothesis that NA and cognitive sequelae would predict performance monitoring dysfunction beyond time since injury, and injury severity. Nineteen survivors of severe TBI completed neuropsychological tests, measures of NA, and a computerized Stroop task. Scores on NA and neuropsychological measures were standardized to form magnitude of cognitive sequelae and negative affect composite scores. Separate hierarchical regression analyses with ERN and Pe amplitudes as dependent variables and injury severity, time since injury, magnitude of cognitive sequelae, and NA as independent variables indicated that NA and cognitive sequelae significantly predicted ERN amplitude, with a larger relative contribution of NA than cognitive sequelae. Increased levels of NA were associated with decreased amplitude ERN. Cognitive sequelae, but not NA, predicted Pe amplitude. Injury severity and time since injury were not significant predictors. Results suggest that both NA and cognitive sequelae play critical roles in performance monitoring decrements following TBI and indicate a possible dissociation between the ERN and Pe, with the ERN more related to affective processes and the Pe to cognitive processes.