Conditions: Alzheimer Disease
Keywords: Alzheimer disease memantine cholinesterase inhibitors magnetic resonance spectroscopy N-acetylaspartate inositol cerebrospinal fluid tau proteins amyloid beta-protein
Allocation: NA | Intervention model: SINGLE_GROUP
Enrollment: 12
Healthy volunteers: no

Brief summary:
We are studying subjects with mild to moderate Alzheimer's disease who have been on a stable dose of any cholinesterase inhibitor \[donepezil (Aricept), rivastigmine (Exelon), or galantamine (Razadyne)\] for at least 3 months, and have not previously taken memantine (Namenda). This is an open-label study, with magnetic resonance spectroscopy (MRS) as the primary outcome measure, along with neuropsychological testing, and optional lumbar puncture, evaluating patients on their stable dose of a cholinesterase inhibitor over 24 weeks, followed by another 24 weeks on memantine in combination with stable dose of cholinesterase inhibitor. The purpose of this study is to characterize the progression of disease using MRS, cerebrospinal fluid (CSF) biomarkers, and cognitive outcome measures, and to determine whether changes in cognitive function on neuropsychological testing are correlated to changes in MR spectroscopic and/or CSF biomarkers.

Detailed description:
Alzheimer's disease (AD) is the most common cause of dementia. The current US prevalence is estimated at over 4 million people, and it ranks as the 8th leading cause of mortality in the United States, accounting for over 60,000 deaths per year.

Memantine is the newest medication approved by the FDA for the treatment of AD. Since it works on a different transmitter system, it can be used in combination with the other FDA-approved treatments for AD, tacrine, donepezil, rivastigmine, or galantamine (collectively referred to as cholinesterase inhibitors).

It remains to be determined what effect currently available AD treatments have on the underlying structural and functional correlates of the dementia process. While preclinical evidence suggests that memantine decreases neuronal toxicity in vitro, it is not clear whether this translates into a beneficial effect in patients with AD.

One of the most pressing challenges underlying clinical trials in AD is the need to validate reliable surrogate biomarkers of disease progression. Proton magnetic resonance spectroscopy (MRS) allows for in vivo detection and measurement of brain metabolites. The spectroscopic features that have been most consistently observed in AD patients, as compared with patients with other causes of dementia, or with normal subjects, have been elevated myo-inositol (mI) and reduced N-acetylaspartate (NAA) .

Evaluation of cerebrospinal fluid (CSF) via lumbar puncture affords a minimally invasive window into the biochemical substrate enveloping the brain. Multiple previous studies of AD patients compared with control subjects have demonstrated decreased CSF beta-amyloid, and elevated CSF tau protein. Previous longitudinal studies have documented the stability of CSF beta-amyloid over one year and CSF tau over two years in AD, suggesting that these may be possible stable target measures for therapeutic intervention.

The purpose of this study is to characterize the progression of disease using MRS, CSF biomarkers, and cognitive outcome measures in patients with mild to moderate Alzheimer's disease after 24 weeks of observational treatment with stable dose of a cholinesterase inhibitor, and after another 24 weeks of open-label memantine treatment in addition to stable dose of a cholinesterase inhibitor.

Arms:
arm 1: 24-week observational lead-in period, wherein patients already on a stable dose of donepezil, rivastigmine, or galantamine continue on that dose, followed by a 24-week open-label memantine period, wherein patients receive open-label memantine treatment titrated to a dose of 20 mg per day, in addition to their ongoing stable cholinesterase inhibitor treatment

Interventions: intervention 1: memantine
Intervention descriptions: intervention 1: 24-week observational lead-in period, wherein patients already on a stable dose of donepezil, rivastigmine, or galantamine continue on that dose, followed by a 24-week open-label memantine period, wherein patients receive open-label memantine treatment titrated to a dose of 10 mg orally b.i.d., in addition to their ongoing stable cholinesterase inhibitor treatment

Protocol document: