A double-blind crossover pilot study of l-deprenyl (selegiline) combined with cholinesterase inhibitor in Alzheimer's disease

Site-activated multi target iron chelators with acetylcholinesterase (AChE) and monoamine oxidase (MAO) inhibitory activities for Alzheimer's disease therapy

The first class of site-activated chelators with dual inhibition of acetyl-cholinesterase (AChE) and monoamine oxidase (MAO), rationally designed for simultaneously targeting the multiple pathogenic processes in Alzheimer's disease (AD) without significantly disrupting healthy metal metabolism in the body are discussed. It is demonstrated that the novel prochelator 2 was a selective and potent MAO-A inhibitor in vitro (IC₅₀: 0.0077 ± 0.0007 μM) with moderate inhibition of MAO-B (IC₅₀: 7.90 ± 1.34 μM). In vitro prochelator 2 also selectively inhibited AChE in a time-dependent manner and reach maximum inhibition of AChE after 2 h preincubation (IC₅₀: 0.52 ± 0.07 μM for AChE, versus 44.90 ± 6.10 μM for BuChE). Prochelator 2 showed little affinity for metal (Fe, Cu, and Zn) ions until it bound to and was activated by AChE that is located predominately in the brain, releasing an active iron chelator M30. M30 is an efficient chelator for metal (Fe, Cu, and Zn) ions with the capabilities to suppress oxidative stress, to selectively inhibit MAO-A and B in the brain, and to regulate cerebral biometals dyshomeostasis in vivo; M30 is also a neuroprotective-neurorestorative chelator with a broad spectrum of activities against β-amyloid (Aβ) generation, amyloid plaques and neurofibrillary tangles (NFT) formation, and Aβ aggregation induced by metal (Cu and Zn) ions. Both M30 and prochelator 2 were not toxic to Human SH-SY5Y neuroblastoma cells at low concentrations, but prochelator 2 shows limited cytotoxicity, at high concentrations. Together, these data suggest that prochelator 2 is a promise lead for simultaneously modulating multiple targets in AD.

Catecholamine-Based Treatment in AD Patients: Expectations and Delusions

In Alzheimer disease, the gap between excellence of diagnostics and efficacy of therapy is wide. Despite sophisticated imaging and biochemical markers, the efficacy of available therapeutic options is limited. Here we examine the possibility that assessment of endogenous catecholamine levels in cerebrospinal fluid (CSF) may fuel new therapeutic strategies. In reviewing the available literature, we consider the effects of levodopa, monoamine oxidase inhibitors, and noradrenaline (NE) modulators, showing disparate results. We present a preliminary assessment of CSF concentrations of dopamine (DA) and NE, determined by HPLC, in a small dementia cohort of either Alzheimer’s disease (AD) or frontotemporal dementia patients, compared to control subjects. Our data reveal detectable levels of DA, NE in CSF, though we found no significant alterations in the dementia population as a whole. AD patients exhibit a small impairment of the DA axis and a larger increase of NE concentration, likely to represent a compensatory mechanism. While waiting for preventive strategies, a pragmatic approach to AD may re-evaluate catecholamine modulation, possibly stratified to dementia subtypes, as part of the therapeutic armamentarium.

Monoamine oxidase inhibitors: promising therapeutic agents for Alzheimer's disease (Review)

Activated monoamine oxidase (MAO) has a critical role in the pathogenesis of Alzheimer's disease (AD), including the formation of amyloid plaques from amyloid β peptide (Aβ) production and accumulation, formation of neurofibrillary tangles, and cognitive impairment via the destruction of cholinergic neurons and disorder of the cholinergic system. Several studies have indicated that MAO inhibitors improve cognitive deficits and reverse Aβ pathology by modulating proteolytic cleavage of amyloid precursor protein and decreasing Aβ protein fragments. Thus, MAO inhibitors may be considered as promising therapeutic agents for AD.

Site-activated chelators targeting acetylcholinesterase and monoamine oxidase for Alzheimer's therapy

Chelators have the potential to treat the underlying cause of Alzheimer's disease (AD), but their therapeutic use is hampered by their poor targeting and poor permeability to the brain and/or toxic effects. Here, we report a new strategy for designing site-activated chelators targeting both acetylcholinesterase (AChE) and monoamine oxidase (MAO). We demonstrated that our lead 2 inhibited both AChE and MAO in vitro, but with little affinity for metal (Fe, Cu, and Zn) ions. Compound 2 can be activated by inhibition of AChE to release an active chelator M30. M30 has been shown to be able to modulate amyloid precursor protein regulation and beta-amyloid reduction, suppress oxidative stress, and passivate excess metal ions (Fe, Cu, and Zn). Compound 2 was less cytotoxic and more lipophilic than the brain-permeable chelator M30. Our new strategy is relatively simple and generally produces small and simple molecules with drug-like properties; it thus holds a potential use in designing site-activated multifunctional chelators with safer and more efficacious properties for treating other metal-related diseases such as Parkinson's disease and cancer where specific elimination of metals in cancer cells is required.

Atomoxetine augmentation of cholinesterase inhibitor therapy in patients with Alzheimer disease: 6-month, randomized, double-blind, placebo-controlled, parallel-trial study

OBJECTIVES

To examine the efficacy and tolerability of atomoxetine (ATX) in improving cognitive performance of patients with Alzheimer dementia.

DESIGN

A randomized, double-blind, placebo (PLA)-controlled, parallel-groups study, starting with a 5-33-day screening and evaluation period, followed by a 6-month treatment period.

SETTING

Eight independent or academic outpatient clinics in the United States.

PARTICIPANTS

Male or female patients, aged 55 years and older, with mild-to-moderate Alzheimer disease (Mini-Mental State Examination score between 10 and 26) at baseline.

INTERVENTION

ATX (25-80 mg/day) or PLA for up to 6 months, added to ongoing cholinesterase-inhibitor therapy.

MEASUREMENTS

Alzheimer Disease Assessment Scale-Cognitive Portion (ADAS-Cog, primary measure), Clinician's Interview-Based Impression of Change score at end point, Neuropsychiatric Inventory, and Alzheimer's Disease Cooperative Study Inventory-Activities of Daily Living Inventory total score, safety measures (secondary measures).

RESULTS

Patients' (N = 92) scores on assessments of cognitive function, global clinical impression, and neuropsychiatric symptoms were not significantly different between treatment groups. Neither group showed significant changes from baseline on the primary measure of efficacy, the ADAS-Cog. The ATX group showed a significantly greater increase of heart rate, and the mean increase in diastolic blood pressure and decrease in weight differed significantly from the decrease in pressure and weight increase in the PLA group. No other clinically meaningful safety results were obtained.

CONCLUSIONS

Addition of ATX to ongoing cholinesterase-inhibitor therapy was generally well tolerated but did not significantly improve cognitive function.

Treating Alzheimer's disease: do clinical trial methods produce unnecessary practitioner dilemmas?

Recent clinical trials and critical reviews of Alzheimer's disease (AD) research discourage already relatively sparing clinical uses of cholinesterase inhibitors (ChEIs) considering the prevalence of AD. As evidence against use of this class of drugs, detractors cite critical reviews of ChEIs and lack of long-term health benefits found in one long-term clinical trial. This paper describes the use of standard error of measurement to allow investigators to design clinical trials that address these issues. The new clinical trial procedures afford sufficient precision for two purposes. First, practitioners can assess individual patients with precision and certainty in their observations. Second, clinical trial researchers can study how short-term drug effects on individual patients predict long-term benefits from continued treatment. With these more clinically informative clinical trial designs, investigators would be able to avoid uncertainties currently raised by conflicts between short- and long-term AD clinical trials.

Effects of selegiline alone or with donepezil on memory impairment in rats

Selegiline, a monoamine oxidase-B inhibitor, is reported to improve memory and learning in dementia of Alzheimer's type. However, only a few studies have reported its use in animal models. Here, we evaluated the effects of selegiline only or its combined use with donepezil, a selective acetylcholinesterase inhibitor on memory impairment, using a Morris water maze. Selegiline dose-dependently attenuated ethylcholine aziridinium ion-induced memory impairment. Co-administration of selegiline and donepezil, at doses that do not exert efficacy individually, significantly ameliorated scopolamine+p-chlorophenylalanine-induced memory deficits. These results suggest that selegiline improves memory impairment mediated by the cholinergic system, and provide evidence of the usefulness of co-treatment with selegiline and donepezil for treating spatial deficits in dementia.

Combination therapy in Alzheimer's disease: a review of current evidence

Treating dementia has become a major challenge in clinical practice. Presently, acetylcholinesterase inhibitors are the first-line drugs in the treatment of Alzheimer's disease (AD). These options are now complemented by memantine, which is approved for the treatment of moderate-to-severe AD. Altogether, a minimum of six agent classes already exist, all of which are approved for clinical use and are either already being tested or ready for phase III clinical trials for the treatment of AD. These include cholinesterase inhibitors, blockers of the NMDA receptor, antioxidants or blockers of oxidative deamination (including Gingko biloba), anti-inflammatory agents, neurotrophic factors (including hormone replacement therapy and drugs acting on insulin signal transduction) and antiamyloid agents (including cholesterol-lowering therapy). These approaches hold promise for disease modification and have a potential to be used as combination therapy for cognitive enhancement. Presently, only nine clinical studies have been published that have investigated the effects of a combination regimen on cognitive performance or AD. Among those, one study was conducted in elderly cognitively intact persons; the others involved patients with AD. Only five of the treatment studies followed a randomised, controlled design. Not all studies favoured the superior efficacy of combination therapy over monotherapy. Some studies, however, showed some evidence for synergistic combination effects of symptomatic therapy, including delay or prevention of disease progression in AD patients. In addition, six studies investigated the effects of AChE inhibitor in combination with antipsychotic or antidepressant therapy on behavioural aspects of AD symptomatology. In four of those studies there were indications that combination therapy had greater efficacy over monotherapy. The treatment of AD patients requires optimised options for all stages of illness based on the available drugs. There is a great need for further well designed studies on combination therapy in AD.

Effects of Galantamine, a Nicotinic Allosteric Potentiating Ligand, on Nicotine-Induced Catecholamine Release in Hippocampus and Nucleus Accumbens of Rats

Galantamine, a drug for treatment of Alzheimer's disease, is a novel cholinergic agent with a dual mode of action that inhibits acetylcholinesterase and allosterically modulates nicotinic cholinergic receptors (nAChRs). Nicotine stimulates catecholamine secretion, inducing hippocampal norepinephrine (NE) release, and improves memory consolidation. Thus, the effect of galantamine on nicotine-induced hippocampal NE secretion was investigated. This was compared with the effect of galantamine on nicotine-induced dopamine (DA) release within the nucleus accumbens of the same rat. Nicotine (0.025-0.09 mg/kg i.v.) dose dependently increased NE and DA levels in microdialysates from the hippocampus and nucleus accumbens, respectively, of freely moving rats. Pretreatment with galantamine (3.0 mg/kg s.c.) 3 h before nicotine either potentiated NE responses to doses of nicotine that were ineffective alone (0.025-0.045 mg/kg) or significantly enhanced (0.065 mg/kg) NE responses, whereas galantamine was ineffective when administered 2 or 4 h before nicotine. In contrast to its effects on NE, galantamine did not alter accumbal DA responses to any dose of nicotine. These selective effects of galantamine on nicotine-stimulated NE secretion may reflect differences in local neural circuits that use nAChRs to modulate hippocampal NE versus accumbal DA release.

Selegiline for Alzheimer's disease

BACKGROUND

Alzheimer's disease is the most common cause of dementia in older people accounting for some 60% of cases with late-onset cognitive deterioration. It is now thought that several neurotransmitter dysfunctions are involved from an early stage in the pathogenesis of Alzheimer's disease-associated cognitive decline. The efficacy of selegiline for symptoms of Alzheimer's disease remains controversial and is reflected by its low rate of prescription and the lack of approval by several regulatory authorities in Europe and elsewhere. Reasons for this uncertainty involve the modest overall effects observed in some trials, the lack of benefit observed in several trials, the use of cross-over designs which harbour methodological problems in a disease like dementia and the difficulty in interpreting results from trials when a variety of measurement scales are used to assess outcomes.

OBJECTIVES

The objective of this review is to assess whether or not selegiline improves the well-being of patients with Alzheimer's disease.

SEARCH STRATEGY

The Cochrane Dementia and Cognitive Impairment Group Register of Clinical Trials, was searched using the terms 'selegiline', 'l-deprenyl', "eldepryl" and "monamine oxidase inhibitor-B". MEDLINE, PsycLIT and EMBASE electronic databases were searched with the above terms in addition to using the group strategy (see group details) to limit the searches to randomised controlled trials.

SELECTION CRITERIA

All unconfounded, double-blind, randomised controlled trials in which treatment with selegiline was administered for more than a day and compared to placebo in patients with dementia.

DATA COLLECTION AND ANALYSIS

An individual patient data meta-analysis of selegiline, Wilcock 2002 provides much of the data that are available for this review. Seven studies provided individual patient data and this was pooled with summary statistics from the published papers of the other nine studies. Where possible, intention-to-treat data were used but usually the meta analyses were restricted to completers' data (data on people who completed the study).

MAIN RESULTS

There are 17 included trials. There were very few significant treatment effects and these were all in favour of selegiline; cognition at 4-6 weeks and 8-17 weeks, and activities of daily living at 4-6 weeks. There is little evidence of adverse effects caused by selegiline, and few withdrew from trials, apart from the Sano trial. The analyses were conducted on data available. There was no attempt to correct for missing patients because there were so few and withdrawal was probably unconnected with treatment. All trials examined the cognitive effects of selegiline, and in addition 12 trials examined the behavioural and mood effects. The meta-analysis revealed benefits on memory function, shown by improvement in the memory tests from several cognitive tests (the Randt Memory Index from Agnoli 1990 and Agnoli 1992, the BSRT from Sunderland 1992, prose recall from Filip 1991, ADAS-cog from Lawlor 1997, the Wechsler Memory Scale from Loeb 1990 and Mangoni 1991, the Rey -AVL from Piccinin 1990, and the MMSE from Sano 1995, Tariot 1998, Filip 1991, Freedman 1996, Burke 1993 and Riekkinen 1993). The combined memory tests, and overall the combined cognitive tests, analysed using standardised mean differences, showed an improvement due to selegiline compared with placebo at 4-6 weeks (SMD 0.39, 95%CI 0.07 to 0.72, P = 0.02, random effects model ) and 8-17 weeks, ( SMD 0.44, 95%CI 0.04 to 0.84, P = 0.03, random effects model). The meta-analyses of emotional state show no treatment effects. Several studies assessed activities of daily living using several different scales, the GBS-motor function from Agnoli 1990, the NOSIE-daily living from Filip 1991, the BDS-daily living from Loeb 1990 and Mangoni 1991, the DS from Sano 1995 and PIADL from Tariot 1998. The combined tests, analysed using the standardised mean difference, showed an improvement due to selegiline at 4-6 weeks (SMD -0.27, 95% CIs -0.41 to -0.13, P = <.001). The global rating scales, the BDS used by Burke 1993 and Tariot 1998, and the GBS used by Agnoli 1990 and Agnoli 1992, and the GDS used by Freedman 1996 and the CGI by Filip 1991, analysed using standardised mean differences showed no effect of selegiline. A variety of adverse effects were recorded, but very few patients left a trial as a direct result. Four studies reported no side effects. Mangoni 1991 reported poor tolerability for 3 patients out of 68 on treatment and 1 out of 51 on placebo, resulting in dropouts. Small numbers found equally in both groups reported anxiety, agitation, dizziness, nausea and dyspepsia. Piccinin 1990 reported that selegiline was well tolerated with few adverse reactions (dizziness and orthostatic hypotension) and no resulting drop outs. Burke 1993 and Loeb 1990 both reported that selegiline was very well tolerated with no serious side effects. Sano 1995 reported 49 categories of adverse events but found no differences between the 4 arms of the factorial trial. Freedman 1996 reported unequal numbers of dropouts in the trial with 7 subjects withdrawing from the selegiline group and only 1 subject from the placebo group. The meta-analyses of the numbers suffering adverse effects, and of the numbers of withdrawals before the end of the trial show no difference between control and selegiline.

REVIEWER'S CONCLUSIONS

Despite its initial promise, ie the potential neuroprotective properties, and its role in the treatment of Parkinson's disease sufferers, selegiline for Alzheimer's disease has proved disappointing. Although there is no evidence of a significant adverse event profile, there is also no evidence of a clinically meaningful benefit for Alzheimer's disease sufferers. This is true irrespective of the outcome measure evaluated, ie cognition, emotional state, activities of daily living, and global assessment, whether in the short, or longer term (up to 69 weeks), where this has been assessed. There would seem to be no justification, therefore, to use it in the treatment of people with Alzheimer's disease, nor for any further studies of its efficacy in Alzheimer's disease.

The effect of selegiline in the treatment of people with Alzheimer's disease: a meta-analysis of published trials

OBJECTIVE

To evaluate the effect of selegiline in the treatment of patients with Alzheimer's disease, in terms of cognitive performance, functional ability, emotional state (including behaviour and mood) and global response. Data Sources The Cochrane database of trials, Embase, Medline and Psychlit. Study Selection Unconfounded, double-blind, randomised trials of selegiline compared with placebo reported before 31 December 1998. Data Extraction The reviewers selected trials for inclusion. Individual patient data were sought, but when these could not be retrieved summary data were extracted from published papers.

RESULTS

Of 27 identified trials, 14 met the inclusion criteria. Individual patient data were retrieved from eight trials on 821 patients. Summary data were extracted from five trials on 240 patients. No data were available from one trial on 12 patients, which was therefore excluded from the meta-analysis. Fixed and random effects meta-analyses were performed on standardised mean differences. For cognition there was a statistically significant difference between selegiline and placebo at 4-6 weeks and 8-17 weeks after randomisation (at 8-17 weeks: smd=0.45 [95% confidence interval 0.03 to 0.88]), but this disappeared at later assessments. The size of the treatment difference was considered unlikely to be of clinical importance. Although there was a statistically significant difference at 4-6 weeks for activities of daily living, this disappeared at later assessments (at 8-17 weeks: smd=0.33 [-0.33, 0.69]). There were no statistically significant differences or clinically relevant differences between selegiline and placebo in terms of emotional state or global response.

CONCLUSION

Although there was some evidence of improvement with selegiline in the short term in cognition and activities of daily living, the magnitude of the effect did not reach clinical importance. There was no evidence of long term effects.

Physostigmine for Alzheimer's disease

BACKGROUND

The main pharmacological approach for the treatment of Alzheimer's disease (AD) has been based on the use of agents potentiating cholinergic transmission, particularly by inhibiting acetylcholinesterase (AChE), the enzyme that destroys acetylcholine after it has been secreted into the synaptic clefts. Physostigmine is an AChE inhibitor originally extracted from calabar beans. It is licensed in many countries as an agent for reversing the effect of drugs and poisons causing the anticholinergic syndrome. Studies conducted more than 20 years ago suggested that physostigmine could improve memory in people with or without dementia. Investigation of this property has been limited by the very short half-life of physostigmine. Various forms of administering the drug have been tried to overcome this problem, most recently a controlled-release (CR) oral formulation, and a skin patch. It has been proposed as a potential drug for the symptomatic treatment of AD.

OBJECTIVES

To determine whether there is evidence of beneficial effects for the use of physostigmine in Alzheimer's disease. To assess the incidence and severity of adverse effects.

SEARCH STRATEGY

The Cochrane Controlled Trials Register was searched using the following terms: 'physostigmine', 'physostigmine salicylate', 'Synapton' and 'Antilirium' in accordance with the Cochrane Dementia and Cognitive Improvement Group's search strategy. The pharmaceutical company was contacted.

SELECTION CRITERIA

All relevant unconfounded, double-blind, randomized, placebo-controlled trials in which physostigmine was administered for more than one day to patients with dementia of Alzheimer type. Trials in which the allocation to the treatment was not randomized, or in which the allocation to the treatment was not concealed were excluded.

DATA COLLECTION AND ANALYSIS

Data were extracted independently by two reviewers (JMC & JB), pooled where appropriate and possible, and the weighted or standardized mean differences or Peto odds ratios (95% CI) were estimated. Where possible, intention-to-treat analysis was used.

MAIN RESULTS

Fifteen studies were included using four different methods of administration of physostigmine. Four studies, involving 29 people in total, used intravenous infusion; seven, involving 131 people, used a conventional oral form; four, involving 1456 participants, used a controlled-release oral form, and one study of 181 people used a verum skin patch. There are no usable results from the intravenous infusion trials, and the few results from the conventional oral form showed no benefit of physostigmine compared with placebo. The results from two of the four studies of the controlled-release physostigmine apply only to a group of patients identified as responders in a pre-randomization titration period. The best dose physostigmine (mean 25mg/day) was associated with a 1.75 point improvement on ADAS-Cog score (mean difference -1.75, 95% confidence interval -2.90, -0.60 on an intention-to-treat basis) and a 0.26 point improvement on the CGIC score (treated as a continuous scale) (mean difference -0.26, 95% confidence interval 0.06, 0.46 on an intention-to-treat basis) compared with placebo at 6 weeks. There were statistically significantly higher numbers of patients from the physostigmine group withdrawing from the trial (22/183 vs 2/183)(OR 5.92, 95% confidence limits 2.59, 13.54) and suffering at least one event of nausea, vomiting, diarhoea, anorexia, dizziness, stomach pain, flatulence or sweating compared with placebo at 6 weeks. The best dose physostigmine (mean 27mg/day) was associated with a 2.0 point improvement on ADAS-Cog score (mean difference -2.02, 95% confidence interval -3.59, -0.45 on an intention to treat basis) compared with placebo at 12 weeks. There were statistically significantly higher numbers of patients from the physostigmine group withdrawing from the trial due to adverse events (13/83 vs 5/93)(OR 3.05, 95% confidence limits 1.15, 8.07) and suffering at least one event of nausea, vomiting, diarhoea, anorexia, dizziness, stomach pain, tremor, asthenia or sweating compared with placebo at 12 weeks. When no attempt was made to identify responders and all relevant patients with Alzheimer's disease were randomized, fixed dose physostigmine (mean 33 mg/day) was associated with a statistically significantly higher number withdrawing (234/358 vs 31/117)(OR 4.82, 95% confidence limits 3.17, 7.33), withdrawing due to adverse events (196/358 vs 10/117) (OR 6.54, 95%confidence limits 4.29, 9.95) and suffering at least one event of nausea, vomiting, diarhoea, anorexia, dizziness, stomach pain, dyspepsia, sweating, asthenia, dyspnoea or abnormal dreaming compared with placebo at 24 weeks. The results from the study of the verum patch physostigmine show that the double dose (delivering mean dose 12mg/day) was associated with statistically significantly higher numbers suffering at least one adverse event of vomiting, nausea or abdominal cramps compared with placebo at 24 weeks, but placebo was associated with statistically significantly greater numbers of gastrointestinal complaints at 24 weeks compared with single-dose physostigmine.

REVIEWERS' CONCLUSIONS

The evidence of effectiveness of physostigmine for the symptomatic treatment of Alzheimer's disease is limited. Even in a controlled release formulation designed to overcome the short half-life, physostigmine showed no convincing benefit and adverse effects remained common leading to a high rate of withdrawal.

Alzheimer's disease: more than a 'cholinergic disorder' - evidence that cholinergic-monoaminergic interactions contribute to EEG slowing and dementia

The loss of cognitive (particularly mnemonic) abilities constitutes a prominent symptom of Alzheimer's disease (AD). These cognitive symptoms occur in close relation to the slowing of the electroencephalogram (EEG), and it is likely that the inability of cortical circuits to maintain an activated state contributes to the behavioral disorganization in AD. The 'cholinergic hypothesis' of AD suggests that many of the cognitive and EEG symptoms are related to the atrophy of basal forebrain cholinergic neurons, which innervate the neocortex and hippocampus, among others. However, data from behavioral and electrophysiological studies in rats suggest that selective reductions in cholinergic transmission result in relatively small mnemonic impairments, and only a partial reduction in EEG activation. Thus, cholinergic atrophy alone may not be sufficient to cause the marked changes in cognition and cortical activity typical of AD. Cholinergic deficits do, however, make neural circuits susceptible to additional neurodegenerative processes. In rats, lowered serotonergic or noradrenergic activity alone often produces only minor impairments in learning/memory tasks and does not block EEG activation. The same monoaminergic deficits, however, result in severe behavioral impairments, and reduce or abolish EEG activation when they occur in a brain already affected by lowered cholinergic activity. There is an abundance of evidence that monoamines are reduced in AD. These degenerative processes, when occurring in a neural environment compromised by cholinergic atrophy, may then contribute to the disturbances in cortical processing and cognition/behavior in AD. A prediction derived from this theory is that an enhancement of monoaminergic functions may have beneficial effects on behavior and cortical activity. Preliminary experiments support this idea: combined cholinergic-monoaminergic stimulation can be more effective in reversing behavioral (Morris water maze) impairments and EEG slowing in rats with multiple neurotransmitter deficiencies than cholinergic enhancement alone. Thus, a stimulation of monoaminergic activity, in conjunction with cholinergic therapies, may provide an effective treatment option for AD.

Free radicals in Alzheimer's dementia: currently available therapeutic strategies

Substantial evidence now exists that oxidative stress may play an important role in the etiopathogenesis of DAT. The different sources of oxidative stress in DAT are suggesting several pharmacological opportunities for influencing the disease. It is possible to distinguish 2 major types of possible therapeutic agents according to their pharmacological point of attack. 1. Radical scavengers, agents directly interacting with free radicals. Candidates of this type are gingko biloba, vitamins A, C, E and estrogen. 2. Antioxidants, which are able to prevent or decrease the production of free radicals by use of specific neuropharmacological properties. Candidates are selegiline, a MAO-B inhibitor well established in the therapy of Parkinson's disease, and tenilsetam, which is believed to be an AGE-inhibitor. Recent in vitro studies have demonstrated the efficacy of both types of therapeutic agents by preventing or delaying oxidative neural damage. Some clinical data exist regarding the antidementive properties particularly in terms of gingko biloba, selegiline and vitamin E. The efficacy studies about these compounds seem to indicate a promising future strategy in the therapy of DAT. But it is too early to draw definite conclusions since it is well known that all of our candidate substances do not act specifically as radical scavengers or antioxidants.

Selegiline in treatment of behavioral and cognitive symptoms of Alzheimer disease

OBJECTIVE

To evaluate the effects of selegiline on behavioral and cognitive symptoms of patients with Alzheimer disease.

DATA SOURCES

An English-language MEDLINE search (1982-1995) was used to identify the review articles and human clinical trials discussed in this article.

STUDY SELECTION

Double- and single-blind and open-label trials were reviewed. Studies were also reviewed if selegiline was evaluated comparatively with other agents. Review articles were used for background information.

DATA EXTRACTION

Data were evaluated from human studies. Studies were critiqued on the basis of design, methodology, duration, sample size, and the degree to which neuropsychological tests used in each study were compared.

DATA SYNTHESIS

Selegiline is a selective, irreversible inhibitor of monoamine oxidase type B. Eight of 11 controlled trials showed selegiline had a positive effect on cognition (e.g., word fluency, delayed recall, total recall). Two of 5 controlled trials evaluating selegiline's effect on behavior (e.g., anxiety, tension, excitement, depression) showed a positive effect.

CONCLUSIONS

The role of selegiline remains to be determined by large well-controlled long-term clinical trials. Selegiline may be a useful agent in managing behavioral and cognitive symptomatology associated with Alzheimer disease. Given that the management of Alzheimer disease is symptomatic and no standard treatment exists, selegiline should be considered among the various options.

The clinical potential of Deprenyl in neurologic and psychiatric disorders

This article reviews the results of clinical studies with Deprenyl in various neurologic and psychiatric disorders except Parkinson's disease. Promising results could be observed both in narcolepsy in a dose of at least 20 mg/day in three different trials and in one study of Tourette's syndrome including attention hyperactivity disorders using an average dosis of 8.1 mg/ day. Controversial results were reported for Alzheimer's disease. On the one hand significant improvement of cognitive functions was found by various authors. On the other hand in a more recent study no effect on the progression of the disease could be observed. For depression a higher dosage of deprenyl between 30 to 60 mg/day appears to be necessary for effective treatment. No positive results were found in amyotrophic lateral sclerosis and in tardive dyskinesias.

L-deprenyl and physostigmine for the treatment of Alzheimer's disease

The present study evaluated the safety of and obtained preliminary data on the cognitive effects of L-deprenyl and physostigmine in patients with Alzheimer's Disease. Seventeen outpatients with Alzheimer's Disease participated in a double-blind crossover study in which they received 4 weeks of L-deprenyl at a dose of 10 mg p.o., q.d., and 4 weeks of placebo in random order. During both the L-deprenyl and placebo periods, patients received cognitive assessments during physostigmine (0.5 mg) and placebo infusions separated by 2 days. The cognitive effects of these agents alone and in combination were measured with digit span, verbal fluency, list learning, praxis, delayed recall, and delayed recognition tasks. Fifteen patients completed the study. The two drugs, used alone or in combination, were safe and well tolerated. Analyses of variance demonstrated that neither physostigmine nor L-deprenyl, whether given alone or in combination, significantly improved cognition, when compared with the double placebo condition.