Changes in CSF acetyl- and butyrylcholinesterase activity after long-term treatment with AChE inhibitors in Alzheimer's disease

OBJECTIVES

  To measure cerebrospinal fluid (CSF) activity of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) in patients with Alzheimer's disease (AD) participating in randomized clinical trials from three European centers, before and after long-term treatment with different AChE inhibitors (AChEIs).

MATERIALS AND METHODS

  Of the 144 patients included in the study, 104 were treated with donepezil, 15 with galantamine, 16 with rivastigmine, and nine with placebo. CSF AChE and BChE activities were measured at baseline and after 1- year treatment.

RESULTS

Donepezil and galantamine groups showed a significant increase in CSF AChE activity at follow-up, while no changes for BChE activity were observed; in donepezil group, a positive correlation between plasma concentration and AChE activity was documented. Conversely, in rivastigmine group, a decrease in CSF activity of both enzymes was observed. CSF AChE and BChE activities were not correlated with the clinical outcome in any group considered. CSF biomarkers did not show any change after treatment.

CONCLUSIONS

  AChEIs differently influence the activity of target enzymes in CSF independent of their pharmacodynamic effects.

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.

CSF biomarkers for Alzheimer's Disease: levels of beta-amyloid, tau, phosphorylated tau relate to clinical symptoms and survival

Cerebrospinal fluid (CSF) samples from 21 patients with a clinical diagnosis of Alzheimer's disease (AD) participating in a 5-year treatment study with the choline esterase inhibitor tacrin were retrospectively analyzed for the contents of beta-amyloid (Abeta42), total tau (T-tau) and phosphorylated tau (P-tau). A significant positive correlation between the level of P-tau and the number of symptoms according to the DSM-IV criteria (p = 0.041) and the NINCDS-ADRDA (p = 0.029) was observed (i.e. higher levels were found in cases with more symptoms). A significant positive correlation between T-tau, P-tau and ADAS-cog score was identified (i.e. higher levels were found with more severe cognitive dysfunction). Patients who died during the 5-year follow-up had significantly lower levels of Abeta42 (p = 0.011) than those who were still alive. Patients who had died in a 6-year follow-up had significantly lower levels of Abeta42 (p = 0.034) and higher levels of T-tau (p = 0.041) than patients still alive.

CONCLUSION

CSF biomarkers do aid the clinical diagnosis of AD. Increased levels of P-tau and T-tau are possible markers for severity and abundance of symptoms in AD. Low levels of Abeta42 may indicate a higher risk of early death in AD.

Five-year outcome of cholinergic treatment of Alzheimer's disease: early response predicts prolonged time until nursing home placement, but does not alter life expectancy

Fifty consecutive outpatients with Alzheimer's disease (AD) received treatment with the cholinesterase inhibitor tacrine in an open longitudinal study. Assessments using Mini-Mental State Examination, Alzheimer's Disease Assessment Scale - cognitive subscale, and a global rating were made at baseline and at 6, 12, 24, 36, 48 and 60 months. Three outcome groups were characterized: responders, unchanged and deteriorated. Additional outcome measures were time until nursing home placement, and mortality rate. At 6 months -75%, at 12 months -42%, at 24 months -20%, and after that 10% of the patients still on medication had improved or remained stable. The mortality rate did not differ between the outcome groups. Response to tacrine treatment at 6 or 12 months was found to predict a prolonged time until nursing home placement. No predictors for a positive treatment response could be identified at baseline.