Randomized Controlled Trial of Mibampator for Behavioral and Psychological Symptoms of Dementia: Comments on the Trial and Thoughts for Future Studies

International Psychogeriatrics (2013), 25:5, 687–689 C International Psychogeriatric Association 2013 doi:10.1017/S1041610213000033 GUEST EDITORIAL Randomized controlled trial of mibampator for behavioral and psychological symptoms of dementia: comments on the trial and thoughts for future studies Behavioral and psychological symptoms of de- (Wang et al., 2009; Corbett et al., 2012) may mentia (BPSD) frequently arise in people with confer benefit in the acute treatment of aggression Alzheimer’s disease (AD) and other dementias. or psychosis, and some possible longer term They cause significant distress and confer risk to benefits for the prophylaxis of these symptoms with the person and others, in addition to presenting a memantine (Ballard et al., 2009b). However, other complex clinical challenge for treatment (Ballard postulated treatments such as sodium valproate and et al., 2009b). There is good evidence for trazodone have not performed well in randomized the value of first-line management strategies controlled trial (RCTs) (Ballard et al., 2009b) and such as psychological interventions and treatment both cholinesterase inhibitors and memantine failed of concurrent medical conditions, particularly to improve agitation in RCTs over 12 weeks pain, which are known to be effective (Ballard (Howard et al., 2007; Fox et al., 2012). Whilst et al., 2009b). However, there are limited there are some potentially promising candidates for pharmacological treatment options for severe further clinical trials, progress has been extremely aggression, which causes significant risk, and for slow. Disappointingly, there has been very little other severe BPSD which do not respond to development work based on understanding of first-line approaches. The only pharmacological the biological mechanisms of key symptoms. The intervention with an adequate evidence base value of this approach has been highlighted is the prescription of atypical antipsychotics, by recent encouraging preliminary evidence for where 18 placebo-controlled trials have evaluated prazosin (Wang et al., 2009), with human autopsy the effect of treatment over 6–12 weeks. The studies indicating the relationship between altered literature indicates modest but significant benefits adrenoceptors and agitation or aggression in people in the treatment of aggression and psychosis with AD (Sharp et al., 2007). The biological basis with risperidone and aripiprazole (Cohen’s d of other BPSD is likely to be different and involves standardized effect size of 0.2), uncertain benefits separate mechanistic pathways. For example, there with olanzapine, and no benefits with quetiapine is no substantive evidence linking delusions to (Ballard and Howard, 2006; Schneider et al., alterations in serotonergic or adrenergic function, 2006a; Ballard et al., 2009b; Corbett et al., but several post-mortem studies do indicate an 2012). Unfortunately, the benefits of longer term association between delusions and upregulation of prescribing are more limited (Schneider et al., post-synaptic muscarinic receptors in the context of 2006b; Ballard et al., 2008) and there have been neurodegenerative dementias (Ballard et al., 2000; increasing concerns regarding the potential for Teaktong et al., 2005). This is consistent with an serious adverse outcomes, including accelerated RCT of the muscarinic agonist xanomeline in AD cognitive decline, stroke, and death (Schneider patients which reported improvements in delusions et al., 2006b; Ballard et al., 2009a). There is (Bodick et al., 1997). This preliminary body of therefore an urgent imperative to identify more evidence does provide support for the potential effective pharmacological treatments for severe value of experimental medicine principles in BPSD which have a better safety profile, particularly identifying new therapies for BPSD, but so far there for long-term treatment and prophylaxis. Despite has been no systematic effort to identify potential this urgency, there has been very little effort agents for repurposing as BPSD treatments and toward developing or evaluating potential novel there has been even less focus on developing novel therapies for the treatment of key symptoms such pharmacological treatments. as aggression, psychosis, restlessness, and apathy. In this edition of International Psychogeriatrics, Several pharmacological alternatives have been Trepacz and colleagues (Trepacz et al., 2013) suggested. Small preliminary trials have indicated report an RCT of the novel glutamatergic that carbamazepine (Olin et al., 2001; Tariot et al., α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic 1998; Ballard et al., 2009b), citalopram (Pollock acid (AMPA) receptor modulator mibampator et al., 2007; Ballard et al., 2009b), and prazosin as a potential treatment for BPSD in AD. The Downloaded from https://www.cambridge.org/core. IP address: 170.106.35.234, on 01 Oct 2021 at 21:34:20, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S1041610213000033 688 C. Ballard et al. AMPA receptor plays a role in the regulation of AMPA system to agitation, aggression, or other the glutamatergic system, which is known to be BPSD. damaged in people with AD. The RCT is well In summary, we urgently need more therapeutic designed and adequately powered, comparing trials evaluating novel pharmacological treatments mibampator to placebo in 132 outpatients with for agitation, aggression, psychosis, and other clinically significant agitation and/or aggression BPSD in order to improve the treatment of these in the context of AD of moderate severity over common and distressing symptoms which signific- 12 weeks. The trial unfortunately demonstrated antly impact upon the lives of people with AD and no efficacy in treating agitation, aggression, or those caring for them. New treatments will be key other neuropsychiatric symptoms, but nevertheless in avoiding an ongoing over-reliance of the use of should be applauded as an excellent example antipsychotic agents as they are currently the only of evaluating a novel therapeutic agent for the evidence-based pharmacological therapy. There are treatment of key BPSD. Many more such trials some methodological issues which could perhaps are urgently needed but it is important to also be usefully addressed by an expert consensus consider potential reasons why the trial was to optimize trial design but, most importantly, unsuccessful in order to strengthen the design it is imperative that we have a strong emphasis of future studies. Although the study followed a on biological mechanisms and plausibility as a well-established design, there are several key points key component of further treatment development within the trial that should be noted, including in this area. We already have good biological the use of concurrent cholinesterase inhibitors targets for repositioned and novel therapeutics, and and memantine, and the use of other psychotropic preliminary evidence of efficacy for some candidate medication. Both cholinesterase inhibitors and therapies. Further development and evaluation of memantine impact on the glutamatergic systems the best candidates is an urgent treatment priority. and it is therefore possible that this activity may have confounded the outcome. Another important point is the high placebo response rate observed in Conflict of interest the trial, which is consistently reported in trials of Clive Ballard has received research funding this nature within this field. In order to ameliorate and consultancy/speaking honoraria from Lun- this effect, an improved design might have been dbeck pharmaceutical company, speaking and the inclusion of an initial lead-in stage or simple consultancy honoraria from Bristol Myer Squibb non-pharmacological intervention to filter out pharmaceutical company, research funding, con- placebo responders prior to randomization. sultancy and speaking honoraria from Acadia If not as a consequence of methodology, why pharmaceutical company. else might mibampator have been ineffective in the Paul Francis has received speaker bureau hon- current RCT? The rationale for taking mibampator oraria, advisory board membership and research forward as a treatment for agitation and aggression funding from Lundbeck pharmaceutical company, was based on a phase II trial of mibampator for expert witness testimony in court cases involving cognition, which did not demonstrate significant Novartis and Janssen Alzheimer Immunotherapy. benefits in terms of cognition, but did result in Anne Corbett has received speaking/consultancy improvement in key BPSD. Whilst this seems very honoraria for Lundbeck, Novartis, Bial, and Acadia reasonable as a potential rationale for taking a pharmaceutical companies. treatment forward to a further trial, there must always be a degree of caution with respect to over- CLIVE BALLARD,PAUL FRANCIS AND interpreting secondary outcome measures from an ANNE CORBETT RCT in the context of multiple outcomes. Whilst Institute of Psychiatry, Wolfson Centre for Age-Related the statistical rationale is clear, the root of the Diseases, King’s College London, London, UK lack of effect may be the absence of a plausible Email: [email protected] biological rationale linking mibampator to agitation, aggression, or other key BPSD. Mibampator is an AMPA receptor potentiator, which plays a role in References the regulation of the glutamatergic system. The AMPA system also has important functions in the Ballard, C. and Howard, R. (2006). Neuroleptic drugs in

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