Noradrenergic activity is associated with response to pindolol in aggressive Alzheimer's disease patients

Locus Coeruleus and Noradrenergic Pharmacology in Neurodegenerative Disease

Adrenoceptors (ARs) throughout the brain are stimulated by noradrenaline originating mostly from neurons of the locus coeruleus, a brainstem nucleus that is ostensibly the earliest to show detectable pathology in neurodegenerative diseases such as Alzheimer's and Parkinson's diseases. The α1-AR, α2-AR, and β-AR subtypes expressed in target brain regions and on a range of cell populations define the physiological responses to noradrenaline, which includes activation of cognitive function in addition to modulation of neurometabolism, cerebral blood flow, and neuroinflammation. As these heterocellular functions are critical for maintaining brain homeostasis and neuronal health, combating the loss of noradrenergic tone from locus coeruleus degeneration may therefore be an effective treatment for both cognitive symptoms and disease modification in neurodegenerative indications. Two pharmacologic approaches are receiving attention in recent clinical studies: preserving noradrenaline levels (e.g., via reuptake inhibition) and direct activation of target adrenoceptors. Here, we review the expression and role of adrenoceptors in the brain, the preclinical studies which demonstrate that adrenergic stimulation can support cognitive function and cerebral health by reversing the effects of noradrenaline depletion, and the human data provided by pharmacoepidemiologic analyses and clinical trials which together identify adrenoceptors as promising targets for the treatment of neurodegenerative disease.

Association of locus coeruleus integrity with Braak stage and neuropsychiatric symptom severity in Alzheimer's disease

The clinical and pathophysiological correlates of locus coeruleus (LC) degeneration in Alzheimer's disease (AD) could be clarified using a method to index LC integrity in vivo, neuromelanin-sensitive MRI (NM-MRI). We examined whether integrity of the LC-norepinephrine system, assessed with NM-MRI, is associated with stage of AD and with neuropsychiatric symptoms (NPS), independent of cortical pathophysiology (amyloid-β and tau burden). Cognitively normal older adults (n = 118), and individuals with mild cognitive impairment (MCI, n = 44), and AD (n = 28) underwent MR imaging and tau and amyloid-β positron emission tomography (with [¹⁸F]MK6240 and [¹⁸F]AZD4694, respectively). Integrity of the LC-norepinephrine system was assessed based on contrast-to-noise ratio of the LC on NM-MRI images. Braak stage of AD was derived from regional binding of [¹⁸F]MK6240. NPS were assessed with the Mild Behavioral Impairment Checklist (MBI-C). LC signal contrast was decreased in tau-positive participants (t₁₈₆ = -4.00, p = 0.0001) and negatively correlated to Braak stage (Spearman ρ = -0.31, p = 0.00006). In tau-positive participants (n = 51), higher LC signal predicted NPS severity (ρ = 0.35, p = 0.019) independently of tau burden, amyloid-β burden, and cortical gray matter volume. This relationship appeared to be driven by the impulse dyscontrol domain of NPS, which was highly correlated to LC signal (ρ = 0.44, p = 0.0027). NM-MRI reveals loss of LC integrity that correlates to severity of AD. However, LC preservation in AD may also have negative consequences by conferring risk for impulse control symptoms. NM-MRI shows promise as a practical biomarker that could have utility in predicting the risk of NPS or guiding their treatment in AD.

Locus coeruleus in memory formation and Alzheimer's disease

Catecholamine neurons of the locus coeruleus (LC) in the dorsal pontine tegmentum innervate the entire neuroaxis, with signaling actions implicated in the regulation of attention, arousal, sleep-wake cycle, learning, memory, anxiety, pain, mood, and brain metabolism. The co-release of norepinephrine (NE) and dopamine (DA) from LC terminals in the hippocampus plays a role in all stages of hippocampal-memory processing. This catecholaminergic regulation modulates the encoding, consolidation, retrieval, and reversal of hippocampus-based memory. LC neurons in awake animals have two distinct firing modes: tonic firing (explorative) and phasic firing (exploitative). These two firing modes exert different modulatory effects on post-synaptic dendritic spines. In the hippocampus, the firing modes regulate long-term potentiation (LTP) and long-term depression, which differentially regulate the mRNA expression and transcription of plasticity-related proteins (PRPs). These proteins aid in structural alterations of dendritic spines, that is, structural long-term potentiation (sLTP), via expansion and structural long-term depression (sLTD) via contraction of post-synaptic dendritic spines. Given the LC's role in all phases of memory processing, the degeneration of 50% of the LC neuron population occurring in Alzheimer's disease (AD) is a clinically relevant aspect of disease pathology. The loss of catecholaminergic regulation contributes to dysfunction in memory processes along with impaired functions associated with attention and task completion. The multifaceted role of the LC in memory and general task performance and the close correlation of LC degeneration with neurodegenerative disease progression together implicate it as a target for new clinical assessment tools.

Randomized Placebo-Controlled Trial of Nabilone for Agitation in Alzheimer's Disease

OBJECTIVE

To investigate the efficacy and safety of nabilone for agitation in patients with moderate-to-severe Alzheimer's disease (AD).

DESIGN

This 14-week randomized double-blind crossover trial compared nabilone to placebo (6 weeks each) with a 1-week washout between phases.

SETTING

Patients were recruited from a long-term care facility and geriatric psychiatry clinics.

PARTICIPANTS

Patients had AD (standardized Mini-Mental State Examination [sMMSE ≤24]) and agitation (Neuropsychiatric Inventory-Nursing Home version [NPI-NH]-agitation/aggression subscore ≥3).

INTERVENTION

Nabilone (target 1-2 mg) versus placebo.

MEASUREMENTS

The primary outcome was agitation (Cohen Mansfield Agitation Inventory [CMAI]). Secondary outcomes included NPI-NH total, NPI-NH caregiver distress, cognition (sMMSE and Severe Impairment Battery [SIB] or Alzheimer's Disease Assessment Scale of Cognition), global impression (Clinician's Global Impression of Change [CGIC]), and adverse events.

RESULTS

Thirty-nine patients (mean ± SD age = 87 ± 10, sMMSE = 6.5 ± 6.8, CMAI = 67.9 ± 17.6, NPI-NH total = 34.3 ± 15.8, 77% male, nabilone dose = 1.6 ± 0.5 mg) were randomized. There were no crossover or treatment-order effects. Using a linear mixed model, treatment differences (95% CI) in CMAI (b = -4.0 [-6.5 to -1.5], t(30.2) = -3.3, p = 0.003), NPI-NH total (b = -4.6 [-7.5 to -1.6], t(32.9) = -3.1, p = 0.004), NPI-NH caregiver distress (b = -1.7 [-3.4 to -0.07, t(33.7) = -2.1, p = 0.041), and sMMSE (b = 1.1 [0.1-2.0], t(22.6) = 2.4, p = 0.026) all favored nabilone. However, in those who completed the SIB (n = 25) treatment differences favored placebo (b = -4.6 [-7.3 to -1.8], t(20.7) = -4.8, p = 0.003). CGIC improvement during nabilone (47%) and placebo (23%) was not significantly different (McNemar's test, exact p = 0.09). There was more sedation during nabilone (45%) compared to placebo (16%) phases (McNemar's test, exact p = 0.02), but treatment-limiting sedation was not significantly different (McNemar's test, exact p = 0.22).

CONCLUSIONS

Nabilone may be an effective treatment for agitation. However, sedation and cognition should be closely monitored.

Noradrenergic pathways of locus coeruleus in Parkinson's and Alzheimer's pathology

Noradrenergic system of brain supplies the neurotransmitter noradrenalin throughout the brain through widespread efferent projections and play pivotal role in cognitive activities and could be involve in motor and non-motor symptoms of Parkinson's disease (PD) pathology. Profound loss of noradrenergic pathways has been reported in both Parkinson's and Alzheimer's disease (AD) pathology however their employment in therapeutics is still scarce. Therefore the present review is providing the various aspects for involvement on noradrenergic pathways in PD and AD pathology as well as the imaging of locus coeruleus as indicative diagnostic marker for disease. The present review is describing about the role of tiny nucleus locus coeruleus located noradrenergic pathways in said pathologies and discussing the past research as well as lacunas in this regard.

Current Agents in Development for Treating Behavioral and Psychological Symptoms Associated with Dementia

Behavioral and psychological symptoms associated with dementia are highly prevalent and are associated with an increased risk of institutionalization and mortality. Current pharmacological treatments for these symptoms include cholinesterase inhibitors, antipsychotics, and selective serotonin reuptake inhibitors. When used for treating behavioral and psychological symptoms associated with dementia, they are associated with limited efficacy and/or serious adverse events. As such, there has been extensive research into novel agents with varying mechanisms of action targeting behavioral and psychological symptoms associated with dementia. In this article, we present the results of a comprehensive literature search and review that evaluates current agents that have completed or are currently in clinical trials for treating behavioral and psychological symptoms associated with dementia as a primary outcome. We highlight novel agents from miscellaneous drug classes, such as dextromethorphan/quinidine, bupropion/dextromethorphan, lumateperone, deudextromethorphan/quinidine, methylphenidate and scyllo-inositol, and drugs from various therapeutic classes (including atypical antipsychotics, selective serotonin reuptake inhibitors, and cannabinoids) that have demonstrated promising results and were generally well tolerated. Future research with large appropriately powered studies using validated outcome measures for behavioral and psychological symptoms associated with dementia should be conducted to further establish the clinical utility of these agents.

Investigating the safety and efficacy of nabilone for the treatment of agitation in patients with moderate-to-severe Alzheimer's disease: Study protocol for a cross-over randomized controlled trial

Agitation is a prevalent and difficult-to-treat symptom in patients with moderate-to-severe Alzheimer's disease (AD). Though there are nonpharmacological and pharmacological interventions recommended for the treatment of agitation, the efficacy of these are modest and not always consistent. Furthermore, the safety profiles of currently prescribed medications are questionable. Nabilone, a synthetic cannabinoid, has a distinct pharmacological profile that may provide a safer and more effective treatment for agitation, while potentially having benefits for weight and pain. Additionally, emerging evidence suggests nabilone may have neuroprotective effects. We describe a clinical trial investigating the safety and efficacy of nabilone for the treatment of agitation in patients with moderate-to-severe AD. This will be a double-blind, randomized cross-over study comparing 6 weeks of nabilone (0.5-2 mg) and placebo, with a 1-week washout preceding each phase. Study outcomes will be measured at baseline and end of treatment for each treatment phase. The primary outcome measure will be agitation as assessed by the Cohen-Mansfield Agitation Inventory. The secondary outcomes include safety, behaviour (Neuropsychiatric Inventory), cognition (standardized Mini Mental Status Exam and either Severe Impairment Battery or Alzheimer's disease Assessment Scale-Cognitive subscale) and global impression (Clinician's Global Impression of Change). Exploratory outcomes include pain (Pain Assessment in Advanced AD), nutritional status (Mini-Nutritional Assessment-Short Form), caregiver distress (NPI caregiver distress), and blood-based biomarkers. A safe and efficacious pharmacological intervention for agitation, with effects on pain and weight loss in patients with moderate-to-severe AD could increase quality-of-life, reduce caregiver stress and avoid unnecessary institutionalization and related increases in health care costs.

Clinical trials number

NCT02351882.

The Neural Mechanism Underlying Cognitive and Emotional Processes in Creativity

Creativity is related to both cognition and emotion, which are the two major mental processes, interacting with each other to form psychological processes. Emotion is the major driving force of almost all creativities, sometimes in an unconscious way. Even though there are many studies concerning the relationship between creativity and cognition, there are few studies about the neural mechanisms of the emotional effects on creativity. Here, we introduce a novel model to explain the relationship between emotions and creativities: Three Primary Color model, which proposes that there are four major basic emotions; these basic emotions are subsided by three monoamines, just like the three primary colors: dopamine-joy, norepinephrine-stress (fear and anger), and serotonin-punishment. Interestingly, these three neuromodulators play similar roles in creativity, whose core features are value and novelty (surprise), like the characteristics of the core features of basic emotions (hedonic value and arousal value). Dysfunctions of these neuromodulators may be the reasons for both psychopathology and creativity, in that they can change the thinking styles such as novelty seeking behavior, hyper-connectivity of brain areas, and/or cognitive disinhibition to induce both creativity and psychopathology. This new model will not only help researchers understand the dynamics of basic emotion elements, it can also bring an entirely new perspective into the relationship between psychopathology and creativity.

Epigenetic dysregulation of brainstem nuclei in the pathogenesis of Alzheimer's disease: looking in the correct place at the right time?

Even though the etiology of Alzheimer's disease (AD) remains unknown, it is suggested that an interplay among genetic, epigenetic and environmental factors is involved. An increasing body of evidence pinpoints that dysregulation in the epigenetic machinery plays a role in AD. Recent developments in genomic technologies have allowed for high throughput interrogation of the epigenome, and epigenome-wide association studies have already identified unique epigenetic signatures for AD in the cortex. Considerable evidence suggests that early dysregulation in the brainstem, more specifically in the raphe nuclei and the locus coeruleus, accounts for the most incipient, non-cognitive symptomatology, indicating a potential causal relationship with the pathogenesis of AD. Here we review the advancements in epigenomic technologies and their application to the AD research field, particularly with relevance to the brainstem. In this respect, we propose the assessment of epigenetic signatures in the brainstem as the cornerstone of interrogating causality in AD. Understanding how epigenetic dysregulation in the brainstem contributes to AD susceptibility could be of pivotal importance for understanding the etiology of the disease and for the development of novel diagnostic and therapeutic strategies.

Use of psychostimulants in patients with dementia

OBJECTIVE

To review the efficacy and safety of psychostimulants for negative behavioral symptoms (ie, apathy, excessive daytime sedation) and cognition in patients with dementia.

DATA SOURCES

Literature was accessed through PubMed and MEDLINE (1966-June 2010), using the terms stimulant, psychostimulant, methylphenidate, dexmethylphenidate, amphetamine, dextroamphetamine, lisdexamfetamine, atomoxetine, modafinil, armodafinil, dementia, Alzheimer disease, vascular dementia, Lewy body dementia, mixed dementia, frontotemporal dementia, therapy, treatment, and therapeutic. Additional references identified from the initial search were reviewed.

STUDY SELECTION AND DATA EXTRACTION

All relevant clinical trials published in English and involving primarily older adults with dementia were included. Case reports, review articles, and other preclinical literature were included as appropriate.

DATA SYNTHESIS

Psychostimulants have been employed as a treatment for cognitive and behavioral symptoms in dementia for decades, but the literature has lagged behind this practice. Eight reports on use of psychostimulants as a treatment of apathy in dementia were reviewed. Methylphenidate was the most frequently studied medication and improvements in apathy were consistently noted; however, the magnitude and duration of effect remain unclear. Six studies examining the cognitive effects of a variety of psychostimulants in patients with dementia were reviewed; psychostimulants had little to no effect on cognition. A lack of studies exists to draw conclusions about the use of psychostimulants for the treatment of excessive daytime sedation in dementia. The possibility of psychostimulants to increase blood pressure; elevate heart rate; and lead to irritability, agitation, and psychosis makes careful patient selection critical, especially in older adults with severe cardiovascular disease or other underlying cardiac abnormalities.

CONCLUSIONS

Based on limited studies, methylphenidate is a possible treatment for apathy in patients with dementia. Psychostimulants, as a group, do not appear to be broadly effective treatments for behavioral or cognitive symptoms of dementia. The potential utility of psychostimulants must be balanced with careful patient selection.

Alternatives to atypical antipsychotics for the management of dementia-related agitation

Numerous recent studies have challenged the widely held belief that atypical antipsychotics are safe and effective options for the treatment of behavioural problems such as agitation in patients with dementia. Accordingly, there is a need to reconsider the place of atypical antipsychotics in the treatment of patients with dementia. The present article is intended to assist clinicians with the assessment and pharmacological management of agitation in patients with dementia. We review the risk-benefit evidence for the use of atypical antipsychotics in patients with dementia-related agitation (DRA). Emerging evidence indicates that, for patients with dementia, the risks associated with atypical antipsychotics may outweigh the benefits except for patients with severe agitation who require short-term chemical restraint. We then discuss the importance of a careful assessment to rule out potentially reversible factors contributing to DRA. Finally, we summarize the evidence supporting the use of medications other than antipsychotics to treat DRA. There is wide variability in the levels of evidence supporting the use of non-antipsychotic medication for the treatment of DRA. The best evidence currently exists for cholinesterase inhibitors and serotonin-specific reuptake inhibitor antidepressants. Emerging reports suggest that numerous other medications, for example, antiepileptics, lithium, anxiolytics, analgesics, beta-adrenoceptor antagonists, cannabinoid receptor agonists and hormonal agents, may prove to be viable alternatives to antipsychotics for the treatment of severe DRA and more research is urgently needed to help assess the effectiveness of these agents. A comprehensive biopsychosocial assessment and treatment plan is likely the most effective way to manage DRA.

Pharmacologic management of neuropsychiatric symptoms of Alzheimer disease

OBJECTIVE

To systematically review published clinical trials of the pharmacotherapy of neuropsychiatric symptoms of Alzheimer disease (AD).

METHOD

We searched MEDLINE and EMBASE for published English-language medical literature. Our review focused on randomized controlled trials (RCTs) and corresponding metaanalyses.

RESULTS

The pharmacotherapy of neuropsychiatric symptoms of AD has been studied with numerous RCTs. The largest number of studies has focused on antipsychotics. Data are of reasonably high quality and indicate that risperidone and olanzapine are more effective than placebo for institutionalized patients with severe agitation, aggression, and psychosis. The efficacy of antipsychotics is counterbalanced by safety concerns that include cerebrovascular adverse events and mortality. Cholinesterase inhibitors and memantine appear to have modest benefits for patients with mildly to moderately severe symptoms. Antidepressants are effective for treating depression in AD, but more data are required to determine the efficacy of trazodone and citalopram for agitation and aggression. Carbamazepine appears to be efficacious, although side effects and concerns about drug-drug interactions limit its use. The data do not support the use of valproate. Benzodiazepines should only be used for short-term, as-needed use. There are insufficient data on other pharmacologic interventions, such as beta blockers, buspirone, and estrogen preparations.

CONCLUSIONS

Although there have been numerous well-designed studies of the pharmacotherapy of neuropsychiatric symptoms in AD, safer and more effective treatments are urgently needed.

Psychiatric and behavioral symptoms in Alzheimer’s disease and other dementias: Etiology and management

Psychiatric and behavioral symptoms are common in all types of dementia and have important consequences for patients, caregivers, and society. This paper reviews recent studies of the etiology and management of these symptoms. Genetic and neurochemical studies indicate that cholinergic, serotonergic, and dopaminergic systems may influence the risk of psychiatric symptoms in patients with dementia. There is still no consensus regarding the management of such symptoms. Controlled studies of psychosocial interventions, usually performed in the nursing home setting, report encouraging results. Atypical antipsychotics may be effective in some cases but have a high risk of adverse events. There is emerging evidence that cholinesterase inhibitors may reduce and prevent such symptoms. More studies are needed to clarify the role of cholinergic and other psychotropic agents as well as nonpharmacologic interventions for psychiatric and behavioral symptoms in patients with dementia.