Onset of Alzheimer disease in apolipoprotein ɛ4 carriers is earlier in butyrylcholinesterase K variant carriers

BACKGROUND

The authors sought to examine the impact of the K-variant of butyrylcholinesterase (BCHE-K) carrier status on age-at-diagnosis of Alzheimer disease (AD) in APOE4 carriers.

METHODS

Patients aged 50-74 years with cerebrospinal fluid (CSF) biomarker-confirmed AD, were recruited to clinical trial (NCT03186989 since June 14, 2017). Baseline demographics, disease characteristics, and biomarkers were evaluated in 45 patients according to BCHE-K and APOE4 allelic status in this post-hoc study.

RESULTS

In APOE4 carriers (N = 33), the mean age-at-diagnosis of AD in BCHE-K carriers (n = 11) was 6.4 years earlier than in BCHE-K noncarriers (n = 22, P < .001, ANOVA). In APOE4 noncarriers (N = 12) there was no observed influence of BCHE-K. APOE4 carriers with BCHE-K also exhibited slightly higher amyloid and tau accumulations compared to BCHE-K noncarriers. A predominantly amyloid, limited tau, and limbic-amnestic phenotype was exemplified by APOE4 homozygotes with BCHE-K. In the overall population, multiple regression analyses demonstrated an association of amyloid accumulation with APOE4 carrier status (P < .029), larger total brain ventricle volume (P < .021), less synaptic injury (Ng, P < .001), and less tau pathophysiology (p-tau181, P < .005). In contrast, tau pathophysiology was associated with more neuroaxonal damage (NfL, P = .002), more synaptic injury (Ng, P < .001), and higher levels of glial activation (YKL-40, P = .01).

CONCLUSION

These findings have implications for the genetic architecture of prognosis in early AD, not the genetics of susceptibility to AD. In patients with early AD aged less than 75 years, the mean age-at-diagnosis of AD in APOE4 carriers was reduced by over 6 years in BCHE-K carriers versus noncarriers. The functional status of glia may explain many of the effects of APOE4 and BCHE-K on the early AD phenotype.

TRIAL REGISTRATION

NCT03186989 since June 14, 2017.

Tau-targeting antisense oligonucleotide MAPTRx in mild Alzheimer's disease: a phase 1b, randomized, placebo-controlled trial

Tau plays a key role in Alzheimer's disease (AD) pathophysiology, and accumulating evidence suggests that lowering tau may reduce this pathology. We sought to inhibit MAPT expression with a tau-targeting antisense oligonucleotide (MAPTRx) and reduce tau levels in patients with mild AD. A randomized, double-blind, placebo-controlled, multiple-ascending dose phase 1b trial evaluated the safety, pharmacokinetics and target engagement of MAPTRx. Four ascending dose cohorts were enrolled sequentially and randomized 3:1 to intrathecal bolus administrations of MAPTRx or placebo every 4 or 12 weeks during the 13-week treatment period, followed by a 23 week post-treatment period. The primary endpoint was safety. The secondary endpoint was MAPTRx pharmacokinetics in cerebrospinal fluid (CSF). The prespecified key exploratory outcome was CSF total-tau protein concentration. Forty-six patients enrolled in the trial, of whom 34 were randomized to MAPTRx and 12 to placebo. Adverse events were reported in 94% of MAPTRx-treated patients and 75% of placebo-treated patients; all were mild or moderate. No serious adverse events were reported in MAPTRx-treated patients. Dose-dependent reduction in the CSF total-tau concentration was observed with greater than 50% mean reduction from baseline at 24 weeks post-last dose in the 60 mg (four doses) and 115 mg (two doses) MAPTRx groups. Clinicaltrials.gov registration number: NCT03186989 .

A double-blind comparison of sertraline and clomipramine in outpatients with obsessive-compulsive disorder

The aim of this study was to compare the efficacy, safety, and tolerability of sertraline and clomipramine in the treatment of obsessive-compulsive disorder (OCD). Outpatients with DSM-III-R defined OCD for 1 year or longer and scores of ≥ 20 on the YaleBrown Obsessive Compulsive Scale (Y-BOCS), ≥ 7 on the National Institute of Mental Health Global Obsessive-Compulsive Scale (NIMH-OC), ≥ 4 on the Clinical Global Impression Severity of Illness Scale (CGI-S) and ≤17 on the Hamilton Depression Scale (17 item HAMD) were randomized to sertraline (n = 86) or clomipramine (n = 82) once daily for 16 weeks. Initial daily doses of sertraline and clomipramine were 50 mg. After a minimum of 4 weeks, these doses could be increased by 50 mg increments every 2 weeks to a maximum of 200 mg daily if the response was thought inadequate. Efficacy was assessed at the end of 1, 2, 4, 6, 8, 12 and 16 weeks of therapy using the Y-BOCS, NIMH-OC, CGI-S, CGI Improvement Scale (CGI-I) and Clinical Anxiety Scale (CAS). One hundred sixty-eight patients were randomized and received at least one dose of double-blind medication; 86 received sertraline and 82 clomipramine. Mean final daily doses at final visit were clomipramine 90 mg (efficacy evaluable patients 101 mg, completers 110 mg), and sertraline 129 mg (efficacy evaluable patients 132 mg, completers 136 mg). Mean baseline Y-BOCS, NIMH-OC and CGI-S totals were 27.7, 10.1 and 5.5, respectively, for sertraline and 27.4, 9.9 and 5.5, respectively, for clomipramine. Sertraline demonstrated greater efficacy than clomipramine in the intent-to-treat patient group: mean baseline to final visit changes were 50.8% (Y-BOCS), 41.9% (NIMH-OC) and 37.7% (CGI-S) for sertraline and 42.9% (Y-BOCS), 33.8% (NIMH-OC) and 30.0% (CGI-S) for clomipramine (P < 0.05). The number of patients withdrawing because of adverse events was substantially greater for clomipramine (26%) than sertraline (11%) (P < 0.05). The most frequent adverse events for clomipramine were dry mouth (20%), anxiety (17%), constipation (16%), nausea (15%) and somnolence (11%), and for sertraline, diarrhea (12%) and nausea (12%). In this study, sertraline was more effective than clomipramine in the intent-to-treat analysis. The difference in efficacy between the treatments is almost wholly accounted for by a greater number of clomipramine withdrawals due to the poor patient acceptance of clomipramine. The superior tolerability of sertraline and the lower rate of premature treatment withdrawal relative to clomipramine may offer considerable quality of life and compliance benefits in the long-term management of a chronic disorder such as OCD.

Targeting Huntingtin Expression in Patients with Huntington's Disease

BACKGROUND

Huntington's disease is an autosomal-dominant neurodegenerative disease caused by CAG trinucleotide repeat expansion in HTT, resulting in a mutant huntingtin protein. IONIS-HTTRx (hereafter, HTTRx) is an antisense oligonucleotide designed to inhibit HTT messenger RNA and thereby reduce concentrations of mutant huntingtin.

METHODS

We conducted a randomized, double-blind, multiple-ascending-dose, phase 1-2a trial involving adults with early Huntington's disease. Patients were randomly assigned in a 3:1 ratio to receive HTTRx or placebo as a bolus intrathecal administration every 4 weeks for four doses. Dose selection was guided by a preclinical model in mice and nonhuman primates that related dose level to reduction in the concentration of huntingtin. The primary end point was safety. The secondary end point was HTTRx pharmacokinetics in cerebrospinal fluid (CSF). Prespecified exploratory end points included the concentration of mutant huntingtin in CSF.

RESULTS

Of the 46 patients who were enrolled in the trial, 34 were randomly assigned to receive HTTRx (at ascending dose levels of 10 to 120 mg) and 12 were randomly assigned to receive placebo. Each patient received all four doses and completed the trial. Adverse events, all of grade 1 or 2, were reported in 98% of the patients. No serious adverse events were seen in HTTRx-treated patients. There were no clinically relevant adverse changes in laboratory variables. Predose (trough) concentrations of HTTRx in CSF showed dose dependence up to doses of 60 mg. HTTRx treatment resulted in a dose-dependent reduction in the concentration of mutant huntingtin in CSF (mean percentage change from baseline, 10% in the placebo group and -20%, -25%, -28%, -42%, and -38% in the HTTRx 10-mg, 30-mg, 60-mg, 90-mg, and 120-mg dose groups, respectively).

CONCLUSIONS

Intrathecal administration of HTTRx to patients with early Huntington's disease was not accompanied by serious adverse events. We observed dose-dependent reductions in concentrations of mutant huntingtin. (Funded by Ionis Pharmaceuticals and F. Hoffmann-La Roche; ClinicalTrials.gov number, NCT02519036.).

Translating Antisense Technology into a Treatment for Huntington's Disease

Advances in molecular biology and genetics have been used to elucidate the fundamental genetic mechanisms underlying central nervous system (CNS) diseases, yet disease-modifying therapies are currently unavailable for most CNS conditions. Antisense oligonucleotides (ASOs) are synthetic single stranded chains of nucleic acids that bind to a specific sequence on ribonucleic acid (RNA) and regulate posttranscriptional gene expression. Decreased gene expression with ASOs might be able to reduce production of the disease-causing protein underlying dominantly inherited neurodegenerative disorders. Huntington's disease (HD), which is caused by a CAG repeat expansion in exon 1 of the huntingtin (HTT) gene and leads to the pathogenic expansion of a polyglutamine (PolyQ ) tract in the N terminus of the huntingtin protein (Htt), is a prime candidate for ASO therapy.State-of-the art translational science techniques can be applied to the development of an ASO targeting HTT RNA, allowing for a data-driven, stepwise progression through the drug development process. A deep and wide-ranging understanding of the basic, preclinical, clinical, and epidemiologic components of drug development will improve the likelihood of success. This includes characterizing the natural history of the disease, including evolution of biomarkers indexing the underlying pathology; using predictive preclinical models to assess the putative gain-of-function of mutant Htt protein and any loss-of-function of the wild-type protein; characterizing toxicokinetic and pharmacodynamic effects of ASOs in predictive animal models; developing sensitive and reliable biomarkers to monitor target engagement and effects on pathology that translate from animal models to patients with HD; establishing a drug delivery method that ensures reliable distribution to relevant CNS tissue; and designing clinical trials that move expeditiously from proof of concept to proof of efficacy. This review focuses on the translational science techniques that allow for efficient and informed development of an ASO for the treatment of HD.

Understanding the beneficial and detrimental effects of donepezil and rivastigmine to improve their therapeutic value

Cholinesterase enzymes metabolize acetylcholine (ACh). Inhibition of acetylcholinesterase (AChE) in damaged but functional cholinergic synapses in the brains of dementia patients increases intrasynaptic ACh. This enhances cholinergic neurotransmission and improves cognition. There is a window of opportunity for this symptomatic treatment effect that opens and closes during the course of dementia depending on when significant synaptic damage occurs. Cholinesterases also metabolize extrasynaptic ACh with butyrylcholinesterase (BuChE) apparently playing the major dynamic role in extracellular ACh homeostasis. Extracellular ACh plays a key regulatory role in controlling the reactivity and functional states of non-excitable cells, such as neuroglia. Current inhibitors of cholinesterases (ChEIs) have similar effects on intrasynaptic ACh, but differ markedly in abilities to upregulate extracellular AChE, inhibit BuChE, and influence the fibrilization of amyloid-β peptides. Importantly, ChEIs can have detrimental disease modifying effects in particular individuals characterized by age, gender, and genotype. In contrast, preliminary evidence suggests that the right dose of the right ChEI in the right patient might significantly slow the progression of neurodegenerative processes. For a particular patient, understanding the condition of cholinergic synapses and the reactivity and functional status of neuroglia could allow administration of appropriate ChEI therapy for symptomatic and disease modifying benefits.

Antidepressant drug development: Focus on triple monoamine reuptake inhibition

Many patients with major depressive disorder (MDD) only partially respond, and some have no clinically meaningful response, to current widely used antidepressant drugs. Due to the purported role of dopamine in the pathophysiology of depression, triple-reuptake inhibitors (TRIs) that simultaneously inhibit serotonin (5-HT), norepinephrine (NE) and dopamine reuptake could be a useful addition to the armamentarium of treatments for MDD. A TRI should more effectively activate mesolimbic dopamine-related reward-networks, restore positive mood and reduce potent 5-HT reuptake blockade associated "hypodopaminergic" adverse effects of decreased libido, weight gain and "blunting" of emotions. On the other hand, dopaminergic effects raise concern over abuse liability and TRIs may have many of the cardiovascular effects associated with NET inhibition. Several clinical development programs for potential TRI antidepressants have failed to demonstrate significantly greater efficacy than placebo or standard of care. Successful late-stage clinical development of a TRI is more likely if experimental research studies in the target population of depressed patients have demonstrated target engagement that differentially and dose-dependently improves assessments of reward-network dysfunction relative to existing antidepressants. TRI treatment could be individualized on the basis of predictive markers such as the burden of decreased positive mood symptoms and/or neuroimaging evidence of reward network dysfunction. This review focuses on how the next generation of monoamine-based treatments could be efficiently developed to address unmet medical need in MDD.

BCL-2 is dispensable for thrombopoiesis and platelet survival

Navitoclax (ABT-263), an inhibitor of the pro-survival BCL-2 family proteins BCL-2, BCL-XL and BCL-W, has shown clinical efficacy in certain BCL-2-dependent haematological cancers, but causes dose-limiting thrombocytopaenia. The latter effect is caused by Navitoclax directly inducing the apoptotic death of platelets, which are dependent on BCL-XL for survival. Recently, ABT-199, a selective BCL-2 antagonist, was developed. It has shown promising anti-leukaemia activity in patients whilst sparing platelets, suggesting that the megakaryocyte lineage does not require BCL-2. In order to elucidate the role of BCL-2 in megakaryocyte and platelet survival, we generated mice with a lineage-specific deletion of Bcl2, alone or in combination with loss of Mcl1 or Bclx. Platelet production and platelet survival were analysed. Additionally, we made use of BH3 mimetics that selectively inhibit BCL-2 or BCL-XL. We show that the deletion of BCL-2, on its own or in concert with MCL-1, does not affect platelet production or platelet lifespan. Thrombocytopaenia in Bclx-deficient mice was not affected by additional genetic loss or pharmacological inhibition of BCL-2. Thus, BCL-2 is dispensable for thrombopoiesis and platelet survival in mice.

Restoration of positive mood states in major depression as a potential drug development target

Restoration of positive mood, in addition to reducing negative mood, is an important treatment goal in the management of depression. The need to restore positive mood states in depressed patients is not adequately addressed by available treatments for major depressive disorder (MDD), suggesting that this mood dimension could be a useful target for drug development. However, for positive mood restoration to become a valid target for antidepressant drug development certain questions should be answered: are symptoms of decreased positive mood phenomenologically distinct from other symptoms of MDD? Should they be considered a distinct aspect of MDD in the diagnostic nomenclature? Is there evidence for differential responsiveness to treatment? Is the underlying pathophysiology understood and different from that of other MDD symptoms? Is low positive mood specific to depression or does it contribute to psychopathology in other disorders? Beyond these basic questions, this review identifies a number of design issues that need to be considered when conducting studies that target improving positive mood. These design issues include (1) what population to study, (2) what line of treatment to target, (3) the appropriateness and validation of methods and measures to evaluate positive mood and its restoration, (4) the role of functional outcome measures in determining success of the treatment, and (5) optimal designs for add-on therapy versus monotherapy agents.

Butyrylcholinesterase genotype and gender influence Alzheimer's disease phenotype

Retrospective data are presented to support a spectrum of early Alzheimer's disease (AD) along a continuum defined by gender and genotype. The putative neurodegenerative mechanisms driving distinct phenotypes at each end of the spectrum are glial hypoactivity associated with early failure of synaptic cholinergic neurotransmission and glial overactivation associated with loss of neural network connectivity due to accelerated age-related breakdown of myelin. In early AD, male butyrylcholinesterase K-variant carriers with one or two apolipoprotein ɛ4 alleles have prominent medial temporal atrophy, synaptic failure, cognitive decline, and accumulation of aggregated beta-amyloid peptide. Increasing synaptic acetylcholine in damaged but still functional cholinergic synapses improves cognitive symptoms, whereas increasing the ability of glia to support synapses and to clear beta-amyloid peptide might be disease-modifying. Conversely, chronic glial overactivation can also drive degenerative processes and in butyrylcholinesterase K-variant negative females generalized glial overactivation may be the main driver from mild cognitive impairment to AD. Females are more likely than males to have accelerated age-related myelin breakdown, more widespread white matter loss, loss of neural network connectivity, whole brain atrophy, and functional decline. Increasing extracellular acetylcholine levels blocks glial activation, reduces myelin loss and damage to neural network connectivity, and is disease-modifying. Between extremes characterized by gender, genotype, and age, pathophysiology may be mixed and this spectrum may explain much of the heterogeneity of amnestic mild cognitive impairment. Preservation of the functional integrity of the neural network may be an important component of strengthening cognitive reserve and significantly delaying the onset and progression of dementia, particularly in females. Prospective confirmation of these hypotheses is required. Implications for future research and therapeutic opportunities are discussed.

Evaluation of dementia rating scales in Parkinson's disease dementia

Disease-specific assessments are not currently available for patients with Parkinson's disease dementia (PDD). This study evaluated the criterion-related validity and test-retest reliability of the Alzheimer's Disease Assessment scale cognitive subscale (ADAS-cog) in terms of sensitivity for differentiation between mild and moderate severity impairment in PDD. Six other dementia rating scales and cognitive tests were also examined. A total of 113 patients with PDD or Alzheimer disease were recruited into this 4-week, multicenter study, segregated into 2 severity groups based on Mini-Mental State Examination (MMSE) score. Mean ADAS-cog scores showed a statistically significant separation between mild and moderate severity patients in both dementias (P < .001). For the ADAS-cog, test-retest Spearman correlation coefficients were significant for each dementia type and severity. This study demonstrated the criterion-related validity and test-retest reliability for ADAS-cog in patients with PDD and strong correlations with MMSE. This supports the validity of previous results obtained with these measures in studies of patients with PDD.

Rivastigmine versus placebo in hyperhomocysteinemic Parkinson's disease dementia patients

The effects of rivastigmine versus placebo in Parkinson's disease dementia (PDD) patients with elevated or normal/low plasma homocysteine were determined. In this prospective analysis of a 24-week, randomly assigned, placebo-controlled study of rivastigmine in PDD, subpopulations comprised patients with plasma homocysteine >or=14 micromol/L (elevated) or <14 micromol/L (normal/low). Coprimary outcomes were the Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-cog) and Alzheimer Disease Cooperative Society-Clinical Global Impression of Change (ADCS-CGIC). Secondary outcomes included additional measures of cognition, including attention and executive function, daily function, and neuropsychiatric symptoms. Adverse events (AEs) were monitored. In total, 342 of 541 patients provided samples for analysis, from which 72% had elevated plasma homocysteine. Hyperhomocysteinemic patients showed treatment differences (rivastigmine vs. placebo) of 4.0 on ADAS-cog and 0.7 on ADCS-CGIC (both P < 0.01), and significant treatment differences on secondary outcomes. Rivastigmine- and placebo-treated hyperhomocysteinemic patients (16.5% and 14.6%) discontinued the study because of AEs. Patients with normal/low homocysteine showed no treatment differences on primary or secondary outcomes (1.4 on the ADAS-cog and 0.1 on ADCS-CGIC, both P = ns); 16.7% and 10.3% rivastigmine- and placebo-treated patients discontinued because of AEs. Elevated homocysteine was associated with greater rivastigmine treatment differences than normal/low homocysteine.

Rivastigmine in Dementia Associated with Parkinson's Disease and Alzheimer's Disease: Similarities and Differences

Parkinson's disease dementia (PDD) and Alzheimer's disease (AD) are both characterized by cognitive abnormalities, neuropsychiatric symptoms, and cholinergic deficits. We reviewed data from large, placebo-controlled clinical trials conducted with rivastigmine in patients with PDD and AD to evaluate similarities and differences in response to treatment. In placebo groups, AD patients appeared to show more rapid cognitive decline than those with PDD. Treatment effects (rivastigmine versus placebo) on cognitive performance over 6 months were quantitatively similar in both populations, but qualitatively different: in AD, cognitive abilities were stabilized by rivastigmine compared to declines in placebo groups, whereas in PDD symptomatic improvements above baseline drove treatment effects while placebo patients had limited change. On activities of daily living, stabilization (rather than improvement) was observed in both dementia types. A more aggressive course of placebo decline, and greater treatment differences (rivastigmine versus placebo), were seen in sub-populations of both PDD and AD patients with hallucinations at baseline. The safety and adverse event profiles were comparable in the two populations. In conclusion, the magnitude of effect with rivastigmine versus placebo is quantitatively comparable in patients with AD and PD, but the treatment effect tended to be one of stabilization in AD, while in PDD improvements over baseline were seen. In both populations, hallucinations may identify patients who are likely to be more treatment-responsive.

Targeting acetylcholinesterase and butyrylcholinesterase in dementia

The cholinesterase inhibitors (ChE-Is) attenuate the cholinergic deficit underlying the cognitive and neuropsychiatric dysfunctions in patients with AD. Inhibition of brain acetylcholinesterase (AChE) has been the major therapeutic target of ChE-I treatment strategies for Alzheimer's disease (AD). AChE-positive neurons project diffusely to the cortex, modulating cortical processing and responses to new and relevant stimuli. Butyrylcholinesterase (BuChE)-positive neurons project specifically to the frontal cortex, and may have roles in attention, executive function, emotional memory and behaviour. Furthermore, BuChE activity progressively increases as the severity of dementia advances, while AChE activity declines. Therefore, inhibition of BuChE may provide additional benefits. The two cholinesterase (ChE) enzymes that metabolize acetylcholine (ACh) differ significantly in substrate specificity, enzyme kinetics, expression and activity in different brain regions, and complexity of gene regulation. In addition, recent evidence suggests that AChE and BuChE may have roles beyond 'classical' co-regulatory esterase functions in terminating ACh-mediated neurotransmission. 'Non-classical' roles in modulating the activity of other proteins, regional cerebral blood flow, tau phosphorylation, and the amyloid cascade may affect rates of AD progression. If these additional mechanisms are demonstrated to underlie clinically meaningful effects, modification of the over-simplistic cholinergic hypothesis in AD that is limited to symptomatic treatment, ignoring the potential of cholinergic therapies to modify the disease process, may be appropriate. The specificity of ChE inhibitory activity, up-regulation of AChE activity and changes in the composition of AChE molecular forms over time, selectivity for AD-relevant ChE molecular forms, brain vs. peripheral selectivity, and pharmacokinetic profile may be important determinants of the acute and long-term efficacy, safety and tolerability profiles of the different ChE-Is. This review focuses on new evidence for the roles of BuChE and AChE in symptom generation and rate of underlying disease progression in dementia, and argues that it may be appropriate to re-evaluate the place of ChE-Is in the treatment of dementia.

Lipid homeostasis and apolipoprotein E in the development and progression of Alzheimer's disease

Extracellular amyloid plaques, intracellular neurofibrillary tangles, and loss of basal forebrain cholinergic neurons in the brains of Alzheimer's disease (AD) patients may be the end result of abnormalities in lipid metabolism and peroxidation that may be caused, or exacerbated, by beta-amyloid peptide (Abeta). Apolipoprotein E (apoE) is a major apolipoprotein in the brain, mediating the transport and clearance of lipids and Abeta. ApoE-dependent dendritic and synaptic regeneration may be less efficient with apoE4, and this may result in, or unmask, age-related neurodegenerative changes. The increased risk of AD associated with apoE4 may be modulated by diet, vascular risk factors, and genetic polymorphisms that affect the function of other transporter proteins and enzymes involved in brain lipid homeostasis. Diet and apoE lipoproteins influence membrane lipid raft composition and the properties of enzymes, transporter proteins, and receptors mediating Abeta production and degradation, tau phosphorylation, glutamate and glucose uptake, and neuronal signal transduction. The level and isoform of apoE may influence whether Abeta is likely to be metabolized or deposited. This review examines the current evidence for diet, lipid homeostasis, and apoE in the pathogenesis of AD. Effects on the cholinergic system and response to cholinesterase inhibitors by APOE allele carrier status are discussed briefly.

Acetylcholinesterase and Its Inhibition in Alzheimer Disease

Until recently, the only established function of acetylcholinesterase (AChE) was the termination of cholinergic neurotransmission. Therefore, the use of AChE inhibitors to treat symptoms caused by cholinergic imbalances in Alzheimer disease (AD) represented a rational approach. However, it is now clear that AChE and the cholinergic system may have broader effects in AD. Of particular interest may be signal transduction pathways mediated through cholinergic receptors that promote nonamyloidogenic amyloid precursor protein processing and decrease tau phosphorylation, and the role of AChE in the aggregation of beta-amyloid (Abeta) peptide. In addition, the neuronal and nonneuronal cholinergic systems have important roles in the modulation of regional cerebral blood flow. These findings may modify the overly simplistic cholinergic hypothesis in AD that is limited to symptomatic treatment and ignores the potential of cholinergic therapies as disease-modifying agents. Chronic increases in AChE activity may exacerbate neurodegenerative processes, make clinically relevant levels of AChE inhibition more difficult to achieve, and cause the therapeutic value of cholinesterase inhibitors (ChE-Is) to be limited and temporary. Rapidly reversible ChE-Is appear to increase AChE activity over the longer term whereas, remarkably, irreversible or very slowly reversible ChE-Is do not seem to have this effect. If such differences between ChE-Is are shown to have clinical correlates, this may prompt reconsideration of the rationale and expectations of some agents in the long-term management of AD.

A placebo-controlled study of sertraline in the treatment of outpatients with seasonal affective disorder

RATIONALE

Seasonal affective disorder (SAD) is a relatively common cyclical depressive illness characterized by seasonal depressions during winter. The disorder is commonly responsive to light therapy, but antidepressant drug efficacy has not been definitely established. Serotonin selective re-uptake inhibitors are potentially efficacious treatments for SAD.

OBJECTIVES

The objective of this study was to evaluate the efficacy, tolerability and safety of sertraline treatment for SAD.

METHODS

One hundred and eighty seven outpatients with seasonal pattern recurrent winter depression (DSM-III-R defined) and a minimum 29-item Hamilton depression scale (SIGH-SAD version) score of 22 were randomized to 8 weeks treatment with either sertraline or placebo in a double-blind, multi-country, multi-center, parallel-group, flexible dose (50-200 mg once daily) study. Efficacy was investigated using physician and patient-rated scales measuring depression, anxiety and symptoms characteristic of seasonal affective disorder.

RESULTS

Sertraline produced a significantly greater response than placebo at endpoint as measured by changes in the 29-item and 21-item Hamilton depression scales, the clinical global impression (CGI) severity scale, the Hamilton anxiety scale, and the hospital anxiety and depression scale. The proportion of sertraline-treated subjects achieving a response on the CGI improvement rating (ratings of 1 or 2) at endpoint (last observation carried forward) was significantly greater than that of the placebo group. Overall sertraline was well tolerated with the most frequent placebo adjusted adverse events, being nausea, diarrhea, insomnia and dry mouth. Adverse events were mostly mild to moderate and transient.

CONCLUSIONS

Sertraline pharmacotherapy has been demonstrated to be an effective and well-tolerated therapy for out patients with SAD. As such, sertraline offers an important pharmacological option in the clinical management of this condition.

Double-blind placebo-controlled pilot study of sertraline in military veterans with posttraumatic stress disorder

The efficacy of sertraline in the treatment of civilian posttraumatic stress disorder (PTSD) has been established by two large placebo-controlled trials. The purpose of the current pilot study was to obtain preliminary evidence of the efficacy of sertraline in military veterans suffering from PTSD. Outpatient Israeli military veterans with a DSM-III-R diagnosis of PTSD were randomized to 10 weeks of double-blind treatment with sertraline (50-200 mg/day; N = 23, 83% male, mean age = 41 years) or placebo (N = 19, 95% male, mean age = 38 years). Efficacy was evaluated by the Clinician-Administered PTSD Scale (CAPS-2) and by Clinical Global Impression Scale-Severity (CGI-S) and -Improvement (CGI-I) ratings. Consensus responder criteria consisted of a 30% or greater reduction in the CAPS-2 total severity score and a CGI-I rating of "much" or "very much" improved. The baseline CAPS-2 total severity score was 94.3 +/- 12.9 for sertraline patients, which is notably higher than that reported for most studies of civilian PTSD. On an intent-to-treat endpoint analysis, sertraline showed a numeric but not statistically significant advantage compared with placebo on the CAPS-2 total severity and symptom cluster scores. In the study completer analysis, the mean CGI-I score was 2.4 +/- 0.3 for sertraline and 3.4 +/- 0.3 for placebo (t = 2.55, df = 30, p = 0.016), CGI-I responder rates were 53% for sertraline and 20% for placebo (chi2 = 3.62, df = 1, p = 0.057), and combined CGI-I and CAPS-2 responder rates (>or=30% reduction in baseline CAPS-2 score) were 41% for sertraline and 20% for placebo (chi2 = 1.39, df = 1, p = 0.238). Sertraline treatment was well tolerated, with a 13% discontinuation rate as a result of adverse events. This pilot study suggests that sertraline may be an effective treatment in patients with predominantly combat-induced PTSD, although the effect size seems to be somewhat smaller than what has been reported in civilian PTSD studies. Adequately powered studies are needed to confirm these results and to assess whether continued treatment maintains or further improves response.

Sertraline treatment of generalized social phobia: a 20-week, double-blind, placebo-controlled study

OBJECTIVE

The authors evaluated the efficacy, safety, and tolerability of sertraline, a selective serotonin reuptake inhibitor, in the treatment of generalized social phobia.

METHOD

Adult outpatients with generalized social phobia (N=204) from 10 Canadian centers were randomly assigned to receive sertraline or placebo in a 2:1 ratio for a 20-week double-blind study following a 1-week, single-blind, placebo run-in. The initial dose of sertraline was 50 mg/day with increases of 50 mg/day every 3 weeks permitted after the fourth week of treatment (dosing was flexible up to a maximum of 200 mg/day). Primary efficacy assessments were the percentage of patients rated much or very much improved on the Clinical Global Impression (CGI) improvement item and the mean changes from baseline to study endpoint in total score on the social phobia subscale of the Marks Fear Questionnaire and total score on the Brief Social Phobia Scale.

RESULTS

In intent-to-treat endpoint analyses of 203 of the patients, significantly more of the 134 patients given sertraline (N=71 [53%]) than of the 69 patients receiving placebo (N=20 [29%]) were considered responders according to their CGI improvement scores at the end of treatment. The mean reductions in the social phobia subscale of the Marks Fear Questionnaire and in the total score on the Brief Social Phobia Scale were 32.6% and 34.3% in the sertraline group and 10.8% and 18.6% in the placebo group, respectively. Analysis of covariance showed superiority of sertraline over placebo on all primary and secondary efficacy measures. Sertraline was well tolerated: 103 (76%) of the 135 sertraline-treated patients and 54 (78%) of the 69 placebo-treated patients completed the study.

CONCLUSIONS

Sertraline is an effective treatment for patients with generalized social phobia.

Prevention of relapse in generalized social phobia: results of a 24-week study in responders to 20 weeks of sertraline treatment

The aim of this study was to evaluate the efficacy, tolerability, and effects on quality of life of sertraline, a selective serotonin reuptake inhibitor, in the prevention of relapse of generalized social phobia. Fifty adult outpatients with generalized social phobia who were rated much or very much improved on the Clinical Global Impression Scale of Improvement (CGI-I) after 20 weeks of sertraline treatment (50-200 mg/day) were randomly assigned in a one-to-one ratio to either continue double-blind treatment with sertraline or immediately switch to placebo for another 24 weeks. The initial 20-week study was placebo-controlled, and 15 responders to placebo also continued to receive double-blind placebo treatment in the continuation study. Eighty-eight percent of patients in the sertraline-continuation group and only 40% of patients in the placebo-switch and placebo-responder groups completed the study. In intent-to-treat endpoint analyses, 1 (4%) of 25 patients in the sertraline-continuation group and 9 (36%) of 25 patients in the placebo-switch group had relapsed at study endpoint (chi2 = 8.0, Fisher exact test, p = 0.01). The relative risk (hazards ratio) for relapse associated with placebo-switch relative to sertraline-continuation treatment was 10.2 (95% confidence interval, 1.3-80.7). Mean CGI-Severity, Marks Fear Questionnaire (MFQ) Social Phobia subscale, and Duke Brief Social Phobia Scale (BSPS) total scores were reduced by 0.07, 0.34, and 1.86 in the Sertraline-Continuation group and increased by 0.88, 4.09, and 5.99 in the Placebo-Switch group (all F > 5.3, p < 0.03), respectively. CGI-Severity, MFQ Social Phobia subscale, and BSPS scores also increased in the Placebo-Responder group. Discontinuations because of lack of efficacy were 4% in the sertraline-continuation group, 28% in the placebo-switch group (chi2 = 5.36, Fisher exact test, p = 0.049), relative to sertraline, and 27% in the placebo-responder group. Sertraline was effective in preventing relapse of generalized social phobia. Future research should assess whether improvements may be maintained or further increased by longer periods of treatment or through the addition of cognitive-behavioral techniques.

Treatment of dysthymia with sertraline: a double-blind, placebo-controlled trial in dysthymic patients without major depression

BACKGROUND

The selective serotonin reuptake inhibitor sertraline has been shown to be efficacious and well tolerated for the treatment of major depressive disorder. Relatively few trials, however, have examined the role of pharmacotherapy in dysthymia without concurrent major depression. The current investigation focuses on the use of sertraline for the treatment of dysthymia.

METHOD

In this 12-week, multicenter, double-blind study, 310 patients with a DSM-III-R diagnosis of dysthymic disorder without concurrent major depression were randomly assigned to receive either sertraline (N = 158) or placebo (N = 152). Sertraline was initiated at a dose of 50 mg daily, with titration permitted to a maximum of 200 mg daily. The primary evaluation criteria were the Structured Interview Guide for the Hamilton Depression Rating Scale, Seasonal Affective Disorder Version (SIGH-SAD), the Montgomery-Asberg Depression Rating Scale (MADRS), and the Clinical Global Impressions-Severity of Illness (CGI-S) and -Improvement (CGI-I) scales.

RESULTS

Mean percentage reductions for the intent-to-treat population in SIGH-SAD scores were 44.6% for the sertraline-treated group and 33.2% for the placebo-treated group (p = .03); MADRS scores, 43.6% and 33.0% (p = .02); and CGI-S scores, 32.8% and 22.8% (p = .02). A significantly greater proportion of the sertraline-treated group was classified as responders (defined for HAM-D and MADRS scores as a 50% score reduction and for CGI-I as a score of 1 or 2 by the final visit) and remitters (SIGH-SAD score < or = 8) relative to the placebo-treated group by the final visit. In addition, sertraline-treated patients experienced greater improvements in all 9 domains of the Battelle Quality of Life Questionnaire than placebo-treated patients did, with a significant difference observed in favor of sertraline in 8 of the 9 domains. The life satisfaction and social interaction quality of life domains showed significantly greater response in sertraline responders compared with placebo SIGH-SAD responders. Sertraline was well tolerated. Thirteen percent of the sertraline-treated group versus 8% of the placebo-treated group withdrew from therapy owing to adverse events (p = .14).

CONCLUSION

Sertraline is efficacious and well tolerated in the short-term treatment of dysthymia without concurrent major depression.

A double-blind study of the efficacy and safety of sertraline and clomipramine in outpatients with severe major depression

This study compared the efficacy and safety of the selective serotonin reuptake inhibitor sertraline with that of the tricyclic antidepressant clomipramine in patients with severe depression, as defined by a baseline 17-item Hamilton Depression Rating Scale (HAM-D) of at least 25. The study included 166 outpatients, randomized to double-blind treatment with sertraline (50-200 mg) or clomipramine (50-150 mg) for 8 weeks. The efficacy of both treatments was similar, 74% of patients in the sertraline group and 71% of clomipramine patients being classified as responders at the end-point, as defined by a Clinical Global Impression-Improvement (CGI-I) score of 1 or 2. Mean HAM-D scores fell from 29.8 at baseline to 12.3 at endpoint in the sertraline group, and from 29.6-12.7 in the clomipramine group. There were more withdrawals due to adverse events in the clomipramine group than in the sertraline group (17% versus 12%). Dry mouth, tremor, dizziness and constipation were all substantially more common in the clomipramine group, whereas diarrhoea/loose stools was more common in the sertraline group. Overall, sertraline was as effective as clomipramine in this group of severely depressed outpatients, and showed better tolerability.

Predictors of an acute antidepressant response to fluoxetine and sertraline

Sertraline and fluoxetine have different pharmacologic and pharmacokinetic profiles which may be of clinical relevance in the determination of response in different subtypes of depression. A randomized, double-blind, 6-week study comparing sertraline (50-100 mg/day) with fluoxetine (20-40 mg/day) in 286 outpatients with major depression, who had demonstrated comparable efficacy and tolerability for the two drugs, was analysed by subgroups of patients at baseline with melancholia, severe depression, single depressive episode, multiple depressive episodes, high anxiety, low anxiety, psychomotor retardation and psychomotor agitation. Multiple logistic regression with regressors including treatment-by-subgroup variables revealed that, within certain subgroups, the efficacy might differ substantially from that of the whole treatment group. However, the only treatment-by-subgroup interaction term that was significant was anxiety (P < 0.05). There was no evidence of interaction in single or recurrent episode subgroups, and these were not included in subsequent analyses. Subsequent two-sample statistical comparison tests of response (i.e. Hamilton Depression Scale reduction > or = 50%) rates at study endpoint between treatment groups demonstrated that patients with melancholic depression and those with symptoms of psychomotor agitation yielded a significantly greater proportion of responders with sertraline compared to fluoxetine (P < 0.05). Response rates in sertraline- and fluoxetine-treated patients, respectively, were: overall study 59%, 51%; melancholia 59%, 44%; severe depression 59%, 41%; low anxiety 71%, 55%; high anxiety 47%, 48%; psychomotor retardation, 48%, 46%; and psychomotor agitation 62%, 39%. Multiple logistic regression adjusting for possible confounding factors, that included a treatment by anxiety interaction term, also led to similar findings. In particular, the analysis showed that significant differences existed in favour of sertraline in patients with low anxiety in the melancholia and severe depression subgroups (P < 0.05), indicating that these characteristics predicted a superior response to 6 weeks of treatment with sertraline relative to fluoxetine. Sertraline also demonstrated advantages over fluoxetine on parameters such as sleep and weight disturbance in severely depressed patients, and sleep disturbance, weight, cognitive disturbance and retardation in melancholic patients.

Chirality and drugs used in psychiatry: nice to know or need to know?

1. Many drugs used to treat psychiatric disorders contain a chiral center or a center of unsaturation and are marketed as a mixture of the resultant enantiomers or geometric isomers, respectively. These enantiomers or geometric isomers may differ markedly with regard to their pharmacodynamic and/or pharmacokinetic properties. 2. Examples of the effects of chiral centers or geometric centers on such properties are given for drugs from the following classes: antidepressants (tricyclics, selective serotonin reuptake inhibitors, monoamine oxidase inhibitors, viloxazine, bupropion, trazodone, mianserin, venlaflaxine); benzodiazepines, zoplicone, and antipsychotics. 3. As described in this review, there are several notable examples of psychiatric drugs currently available where the individual enantiomers or geometric isomers differ considerably with regard to factors such as effects on amine transport systems, interactions with receptors and metabolizing enzymes, and clearance rates from the body. Indeed, relatively recent developments in analytical and preparative resolution of racemic and geometric drug mixtures and increased interest in developing new drugs which interact with specific targets, which have been described in detail at the molecular level, have resulted in increased emphasis on stereochemistry in drug development.

Effects of SSRIs on sexual function: a critical review

Sexual problems are highly prevalent in both men and women and are affected by, among other factors, mood state, interpersonal functioning, and psychotropic medications. The incidence of antidepressant-induced sexual dysfunction is difficult to estimate because of the potentially confounding effects of the illness itself, social and interpersonal comorbidities, medication effects, and design and assessment problems in most studies. Estimates of sexual dysfunction vary from a small percentage to more than 80%. This article reviews current evidence regarding sexual side effects of selective serotonin reuptake inhibitors (SSRIs). Among the sexual side effects most commonly associated with SSRIs are delayed ejaculation and absent or delayed orgasm. Sexual desire (libido) and arousal difficulties are also frequently reported, although the specific association of these disorders to SSRI use has not been consistently shown. The effects of SSRIs on sexual functioning seem strongly dose-related and may vary among the group according to serotonin and dopamine reuptake mechanisms, induction of prolactin release, anticholinergic effects, inhibition of nitric oxide synthetase, and propensity for accumulation over time. A variety of strategies have been reported in the management of SSRI-induced sexual dysfunction, including waiting for tolerance to develop, dosage reduction, drug holidays, substitution of another antidepressant drug, and various augmentation strategies with 5-hydroxytryptamine-2 (5-HT2), 5-HT3, and alpha2 adrenergic receptor antagonists, 5-HT1A and dopamine receptor agonists, and phosphodiesterase (PDE5) enzyme inhibitors. Sexual side effects of SSRIs should not be viewed as entirely negative; some studies have shown improved control of premature ejaculation in men. The impacts of sexual side effects of SSRIs on treatment compliance and on patients' quality of life are important clinical considerations.

SSRI-induced extrapyramidal side-effects and akathisia: implications for treatment

The selective serotonin reuptake inhibitors (SSRIs) may occasionally induce extrapyramidal side-effects (EPS) and/or akathisia. This may be a consequence of serotonergically-mediated inhibition of the dopaminergic system. Manifestations of these effects in patients may depend on predisposing factors such as the presence of psychomotor disturbance, a previous history of drug-induced akathisia and/or EPS, concurrent antidopaminergic and/or serotonergic therapy, recent monoamine oxidase inhibitor discontinuation, comorbid Parkinson's disease and possibly deficient cytochrome P450 (CYP) isoenzyme status. There is increasing awareness that there may be a distinct form of melancholic or endogenous depression with neurobiological underpinnings similar to those of disorders of the basal ganglia such as Parkinson's disease. Thus, it is not surprising that some individuals with depressive disorders appear to be susceptible to developing drug-induced EPS and/or akathisia. In addition, the propensity for the SSRIs to induce these effects in individual patients may vary within the drug class depending, for example, on their selectivity for serotonin relative to other monoamines, affinity for the 5-HT2C receptor, pharmacokinetic drug interaction potential with concomitantly administered neuroleptics and potential for accumulation due to a long half-life. The relative risk of EPS and akathisia associated with SSRIs have yet to be clearly established. The potential risks may be reduced by avoiding rapid and unnecessary dose titration. Furthermore, early recognition and appropriate management of EPS and/or akathisia is required to prevent the impact of these effects on patient compliance and subjective well-being. It is important that the rare occurrence of EPS in patients receiving SSRIs does not preclude their use in Parkinson's disease where their potentially significant role requires more systematic evaluation.

SSRIs and hyponatraemia

Increasing age, certain medications such as diuretics, disease processes such as malignant neoplasm and schizophrenia, and a history of hyponatraemia or polydipsia may predispose patients to the development of hyponatraemia. In addition, certain psychotropic medications, including TCAs, MAOIs, carbamazepine, trazodone and neuroleptics, may predispose to hyponatraemia, yet a causative role for most has not been firmly established and the effect is most likely to be more idiosyncratic. The SSRIs have been associated with hyponatraemia in a small number of case reports. The mean age and sex of patients in reported cases is over 70 years and predominantly female, and patients were often receiving concomitant diuretic therapy. The frequency of hyponatraemia in elderly female patients receiving fluoxetine has been estimated to be as high as eight per 1000. The risk of developing hyponatraemia appears to be highest during the first few weeks of treatment. Because of the potential seriousness of hyponatraemia, if an elderly patient receiving an SSRI develops unexplained symptoms during the first few weeks of therapy, it is necessary to measure the serum sodium level.

A critical review of selective serotonin reuptake inhibitor-related sexual dysfunction; incidence, possible aetiology and implications for management

There is a high incidence of sexual dysfunction in the general population and sexual dysfunction is often an integral symptom of a depressive disorder. In addition, all antidepressants have effects on sexual functioning, as the result of side-effects of these medications and as a reflection of therapeutic success. The selective serotonin reuptake inhibitors (SSRIs) are clearly associated with delayed ejaculation, inability to ejaculate and absent or delayed orgasm. Furthermore, the incidence of sexual dysfunction obtained by patient self-report does not appear to reflect the true incidence of sexual dysfunction associated with antidepressant therapy and systematic inquiry is needed as sexual dysfunction may be an unrecognized cause of noncompliance. The SSRIs may have advantageous effects on sexual functioning and these may also be underreported due to the same factors resulting in an under-reporting of sexual side-effects in general. In addition, studies have suggested a role for the SSRIs in the management of premature ejaculation. The effects of SSRIs on sexual functioning are clearly dose-related and may vary amongst the group due to their relative effects on the serotonin and dopamine systems and the extent to which plasma levels of these drugs accumulate in the body over time. A variety of strategies have been found useful in the management of SSRI-induced sexual dysfunction including waiting for tolerance to develop, dosage reduction, drug holidays, switching to a different antidepressant and various augmentation strategies with 5-HT2, alpha2 adrenergic receptor antagonists and dopamine receptor agonists.

Pharmacokinetic drug interaction potential of selective serotonin reuptake inhibitors

Obsessive-compulsive disorder (OCD) is a chronic disorder requiring long-term treatment. The pharmacological management of the disorder, therefore, requires the use of agents which, in addition to being efficacious and well tolerated, are unlikely to cause pharmacokinetic drug-drug interactions with concomitantly administered medication which the patient is receiving or may receive in the future. The selective serotonin reuptake inhibitors (SSRIs) have similar pharmacodynamic profiles but their pharmacokinetic profiles are very different. Perhaps the most substantial pharmacokinetic difference among these drugs is in their potential for drug-drug interactions via the inhibition of cytochrome P450 (CYP) isoenzymes. This review provides comprehensive background information on these enzyme systems and discusses their significance with respect to the optimal care of patients. Fluoxetine is a substantial inhibitor of CYP2D6, has mild effects on CYP3A3/4, and may also have effects on CYP2C9/10 and CYP2C19. Effects on drugs metabolized by these enzymes can persist for many weeks after fluxoetine discontinuation due to the long half-life of fluoxetine and its active metabolite norfluoxetine. Fluvoxamine is a substantial inhibitor of CYP1A2 and CYP2C19, and a moderate inhibitor of CYP3A3/4. Paroxetine is a substantial inhibitor of CYP2D6. In contrast, sertraline and citalopram are mild inhibitors of CYP2D6 at their usually effective doses and are not known to produce clinically meaningful inhibition of any other isoenzymes. However, citalopram has not been well studied against all of these enzymes, especially in vivo. An increased risk of pharmacokinetic drug interactions is the immediate clinical consequence of the inhibitory effects of these drugs on CYP isoenzymes. However, with the emphasis on long-term treatment, particularly in chronic conditions such as OCD, it will also be important to determine the long-term clinical consequences of substantially inhibiting specific CYP isoenzymes with those SSRIs which have these effects. Thus knowledge of the substrates and inhibitors of CYP isoenzymes may help clinicians to anticipate and avoid pharmacokinetic drug interactions and may better define rational prescribing practices.

Sertraline 50 mg daily: the optimal dose in the treatment of depression

The dose regimen for sertraline in the treatment of depression has been well established. The starting dose, 50 mg/day, is the usually effective therapeutic dose, and the optimal dose when considering both efficacy and tolerability for most patients. For patients who do not show an adequate therapeutic response within 24 weeks, the dose of sertraline can be increased in 50 mg/day increments at no less than weekly intervals to a maximum of 200 mg/day. Sertraline is generally given as a single daily dose and may be administered at any time of the day. In contrast to other selective serotonin reuptake inhibitors, there is no need for altered dose recommendations in the elderly.

Pharmacotherapy of the depressed patient with cardiovascular and/or cerebrovascular illness

Cardiovascular and cerebrovascular disease are associated with a high incidence of depressive disorder. Despite this high level of co-morbidity, depressive disorders appear to go largely unrecognised and remain untreated. This may have serious consequences, as concomitant depression worsens the prognosis in patients with cardiovascular or cerebrovascular disease, increases medical costs, and delays return to work. Treatment with traditional tricyclic antidepressants is difficult in these patients because of the known cardiac effects. The favourable side-effect profiles of the 5-HT reuptake inhibitors suggest that they may offer therapeutic advantages, as they have little or no effect on cardiac conduction, do not cause orthostatic hypotension, and lack serious sequelae in overdose. The pharmacological profiles and the reduced potential of these newer antidepressant drugs to cause drug interaction show important differences that may be of clinical relevance in this patient population.

The effects of a dentifrice containing a zinc salt and a non-cationic antimicrobial agent on plaque and gingivitis

The antiplaque potential of metal salts in mouthwashes or dentifrices has been previously demonstrated. The purpose of the present investigation was to establish the effects on plaque and gingival health of a dentifrice which contained a combination of the metal salt, zinc citrate, and the anti-microbial agent, Triclosan. Plaque growth was reduced by a dentifrice which contained either zinc citrate or triclosan, but greater inhibition was achieved with dentifrices which contained both agents. A 4-day non-brushing study in which slurries of the dentifrice were used, confirmed that the test dentifrice which contained 1% zinc citrate and 0.5% Triclosan reduced the accumulation of plaque by 50%. In a double-blind crossover study of 28 days duration, a significant reduction in plaque accumulation and an improvement in gingival health was demonstrated for the test dentifrice compared to the placebo. Further analysis of the data indicated that the dentifrice was most efficacious for participants who brushed ineffectively. Also, the greatest benefit was obtained by subjects that used the largest amount of dentifrice.