Donepezil in Alzheimer's disease: what to expect after 3 years of treatment in a routine clinical setting

Disease progression meta-analysis model in Alzheimer's disease

BACKGROUND

Various authors have evaluated disease progression in Alzheimer's disease (AD), using patient data from individual clinical studies or pooled data across various trials. We conducted a systematic review of public data sources from 1990 to 2008 for all available AChE inhibitor studies, as well as clinical studies that evaluated the rate of deterioration in AD patients. Unique to this analysis, we developed a model based on literature data to describe the longitudinal response in the Alzheimer's Disease Assessment Scale-Cognitive (ADAS-cog) (change from baseline) in mild to moderate severity AD patients. The model was used to estimate disease progression for both placebo-treated patients and acetylcholinesterase (AChE)-inhibitor treated patients, and factors that affected disease progression.

METHODS

We collected 576 mean ADAS-cog changes from baseline data points of 52 trials, representing data from approximately 19,972 patients and more than 84,000 individual observations. The model described the rate of disease progression, the evident placebo effect, and the symptomatic effect of AChE-inhibitors. Baseline ADAS-cog, Mini-Mental State Examination score, age, and year of publication were tested as covariates.

RESULTS

The disease progression in mild to moderate AD patients across all available and relevant literature sources was estimated as 5.5 points per year. An Emax-type model best described the symptomatic drug effect of AChE inhibitors. The rate of disease progression (underlying disease progression) was no different between placebo and AChE-inhibitors groups. Baseline ADAS-cog is a significant covariate in disease progression. Baseline age was also tested as a covariate in the rate of disease progression, but the model was unable to describe any effects of age, likely because of the narrow distribution of mean age (literature-level analysis). There was no significant impact of publication year in the model.

CONCLUSIONS

Baseline ADAS-cog is a significant covariate affecting the rate of disease progression, and it describes or at least explains the different rates of deterioration evident in early or late stages of the disease. There was no significant impact of publication year in the model, suggesting that disease progression has not slowed in more recent trials.

Can CSF biomarkers or pre-treatment progression rate predict response to cholinesterase inhibitor treatment in Alzheimer's disease?

OBJECTIVE

The main objective of this study was to investigate possible predictors of response to cholinesterase inhibitor (ChEI) treatment, including pre-treatment progression rates and levels of the cerebrospinal fluid (CSF) biomarkers. A secondary objective was to evaluate whether treatment with ChEI changed progression.

METHODS

Out-patient individuals (n = 191) with the clinical diagnosis of Alzheimer's disease received ChEI treatment and were part of the Swedish Alzheimer Treatment Study (SATS), a prospective, longitudinal, non-randomised study in a routine clinical setting. Patients were assessed with MMSE, ADAS-cog and a global rating (CIBIC) at baseline, 2 months and every 6 months for a total period of 3 years. The following potential predictors of treatment response were investigated: age, gender, APOE epsilon 4 carrier, education, duration of disease, cognitive level, pre-treatment progression rate (in MMSE) and the levels of the CSF biomarkers A beta 42, T-tau and P-tau.

RESULTS

Fast pre-treatment progression rate was a predictor of treatment response even after adjusting for baseline severity, another positive predictor of response. Patients in the fastest quartile of pre-treatment progression rates were significantly more prone to be responders at 2 months (adjusted OR 6.6, p = 0.001) and 6 months (adjusted OR 10.4, p < 0.001) than those in the slowest progressing quartile. Moreover, the linearity of progression was significantly changed by ChEI treatment at 6 months compared to the pre-treatment period.

CONCLUSION

The rate of pre-treatment progression was the most consistent positive predictor of ChEI treatment response in the routine clinical setting. The progression rate was significantly changed by ChEI treatment.

Long-term rivastigmine treatment in a routine clinical setting

OBJECTIVE

The aim of the study was to observe the effects of long-term rivastigmine treatment in patients with mild to moderate Alzheimer's disease (AD) in a routine clinical setting.

METHODS

This was a prospective, open-label, observational, multicentre, non-randomized study. Outcome measures included the Mini Mental State Examination (MMSE), the Clinician's Interview-Based Impression of Change (CIBIC) and the Alzheimer's Disease Assessment Scale - cognitive subscale (ADAS-cog).

RESULTS

Of 217 patients initiated into rivastigmine treatment, 62% (n = 135) remained on treatment for 24 months. Most patients droped out due to nursing home placement or side effects. Eighty per cent and 67% of completers exhibited a symptomatic attenuation of cognitive decline (< or = 4-point deterioration) as assessed by using the MMSE and ADAS-cog respectively. Forty-four per cent showed an unchanged/improved CIBIC rating.

CONCLUSIONS

Over 60% of patients remained on treatment for 2 years in this routine clinical setting. In patients who remained on treatment, rivastigmine appeared to stabilize their condition and prevented or delayed symptomatic decline.

Changes in cognitive domains during three years in patients with Alzheimer's disease treated with donepezil

Background

The objective was to identify separate cognitive domains in the standard assessment tools (MMSE, ADAS-Cog) and analyze the process of decline within domains during three years in Alzheimer's disease (AD) patients with donepezil treatment.

Method

AD patients (n = 421) were recruited from a clinical multi-centre study program in Sweden. Patients were assessed every six months during three years. All patients received donepezil starting directly after study entry. After dropouts, 158 patients remained for analyses over three years. Data for the other patients were analysed until they dropped out (4 groups based on length in study).

Results

Factor analyses of all items suggested that there were three intercorrelated factors: a General, a Memory and a Spatial factor for which we constructed corresponding domains. Overall there was a cognitive improvement at six months followed by a linear drop over time for the three domains. Some group and domain differences were identified. Patients who remained longer in the study had better initial performance and a slower deterioration rate. The early dropouts showed no improvement at six months and many dropped out due to side effects. The other groups displayed a performance improvement at six months that was less pronounced in the Memory domain. Before dropping out, deterioration accelerated, particularly in the Spatial domain.

Conclusion

The course of illness in the three domains was heterogeneous among the patients. We were not able to identify any clinically relevant correlates of this heterogeneity. As an aid we constructed three algorithms corresponding to the cognitive domains, which can be used to characterize patients initially, identify rapid decliners and follow the course of the disease.

Acute but not chronic donepezil increases muscarinic receptor-mediated signaling via arachidonic acid in unanesthetized rats

Donepezil, an acetylcholinesterase (AChE) inhibitor used for treating Alzheimer's disease patients, is thought to act by increasing brain extracellular acetylcholine (ACh), and ACh binding to cholinergic receptors. Muscarinic receptors are coupled to cytosolic phospholipase A2 (cPLA2) activation and arachidonic acid (AA) release from synaptic membrane phospholipid. This activation can be imaged in rodents as an AA incorporation coefficient k*, using quantitative autoradiography. Acute and chronic effects of donepezil on the AA signal, k* for AA, were measured in 81 brain regions of unanesthetized rats. Twenty min after a single oral dose (3.0 mg/kg) of donepezil, k* was increased significantly in 37 brain regions, whereas k* did not differ from control 7 h afterwards or following chronic (21 days) of donepezil. Pretreatment with atropine prevented the 20-min increments in k* following donepezil. Donepezil also increased the brain ACh concentration and reduced brain AChE activity, but did not change cPLA2 activity, regardless of administration regimen. These results show that donepezil acutely increases the brain AA signal that is mediated by ACh acting at muscarinic receptors, but that this signal is rapidly desensitized despite continued elevated brain ACh concentration. In contrast, the AA signal in response to arecoline was not altered following donepezil.

The usefulness of cube copying for evaluating treatment of Alzheimer's disease

AIMS

Cube copying measures visuospatial ability, which is often impaired in Alzheimer's disease (AD). Cube copying was examined as an evaluation of cholinesterase inhibitor (ChEI) treatment in AD.

METHODS

Eighty-five ChEI-treated AD patients were included. Cube drawings made at prebaseline, baseline, 6 months, and 12 months were assessed. Cube drawings from 56 healthy individuals were also examined.

RESULTS

The healthy individuals remained stable in cube copying, whereas untreated AD patients deteriorated during a median period of 6 months. When treatment was given, the deterioration was interrupted. After 12 months, Mini-Mental State Examination (MMSE) had deteriorated compared with baseline whereas cube copying was unchanged.

CONCLUSIONS

The results indicate that cube copying can be used to evaluate ChEI treatment. It might also show a more long-lasting response to treatment than MMSE. Cube copying only measures a narrow cognitive function and can preferably be used with MMSE, which evaluates visuospatial ability poorly.