Metformin in Amnestic Mild Cognitive Impairment

Phase 2

Completed

Conditions: Mild Cognitive Impairment

Interventions: Drug: Placebo
Drug: Metformin

Registration Number: NCT00620191

Lead Sponsor: Columbia University

Brief Summary: Hyperinsulinemia and type 2 diabetes (T2D) are important potential risk factors for cognitive decline and Alzheimer's disease (AD). Two thirds of the US adult population are at risk for hyperinsulinemia and T2D, and half of the population 85 years and older have AD. Peripheral hyperinsulinemia can impair the clearance of amyloid beta in the brain, the main culprit in AD. Thus, the investigators hypothesize that lowering peripheral insulin in overweight persons with amnestic mild cognitive impairment (AMCI), a transition state between normal cognition and AD, can decrease the risk of cognitive decline and progression to AD. The investigators propose to conduct a phase II double blinded placebo controlled randomized clinical trial of metformin, a safe and effective medication that prevents hyperinsulinemia and diabetes, to test this hypothesis among 80 overweight persons aged 55 to 90 years with AMCI. The main outcome of the study will be changes in performance in a memory test (total recall of the Selective Reminding Test) and the Score a test of general cognitive function used in clinical trials (the Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-Cog)). Another aim is to compare brain function in an area affected by Alzheimer's disease between the metformin and placebo group mean changes from beginning to end among 40 participants using a PET scan.

Detailed Description: The prevalence of Alzheimer's disease (AD) is expected to quadruple by the year 2047. There are no known curative or preventive measures for AD. Current treatment options for AD only address symptoms, and no treatments are available that focus on delaying the actual disease process. One of the currently accepted hypothesis of the pathogenesis of AD is that the main culprit is the accumulation of Aβ in the brain, and this process has become a target for treatments and preventive measures. Amnestic mild cognitive impairment (MCI) has been used to describe a transitional state between normal cognitive function and AD, and has thus been targeted for interventions. Persons with MCI progress to AD at the rate of nearly 10% to 15% per year. The criteria most commonly used for the definition of AD dementia from MCI. The investigators propose to use these criteria with slight modification to recruit persons for a pilot trail of AD prevention in persons with amnestic MCI.

Peripheral hyperinsulinemia (high insulin levels) potentially impair Aβ clearance, and in this study we are proposing to use metformin, an insulin lowering agent, to prevent AD by improving Aβ clearance in the brain. The insulin resistance syndrome and hyperinsulinemia are common in individuals with and without diabetes, and are related to increased risk of cardiovascular and cerebrovascular outcomes. Hyperinsulinemia predicts the development of diabetes; therefore, diabetes can be considered a consequence and a marker of past hyperinsulinemia. According to NHANES III data, more than 40% of the population over the age of 60 years has problems of glucose intolerance or diabetes, all related to insulin resistance and hyperinsulinemia. The investigators have found that the risk of AD in individuals without diabetes increases with increasing levels of fasting insulin, and that high insulin levels are related to a faster decline in memory scores. The high prevalence of hyperinsulinemia and diabetes (49% of the elderly in Northern Manhattan) and its biological plausibility as a risk factor for cognitive decline and AD has attracted increasing attention. In this application we are targeting hyperinsulinemia, the most important risk factor for AD identified in the elderly population of Northern Manhattan. The risk of AD attributable to hyperinsulinemia or diabetes in Northern Manhattan was 39%, and is higher in Hispanics and African-Americans, who have a higher prevalence of diabetes and insulin resistance, and will comprise the majority of our sample.

Recruitment & Eligibility

Status: COMPLETED

Sex: All

Target Recruitment: 80

Inclusion Criteria

Not provided

Exclusion Criteria

Not provided

Study & Design

Study Type: INTERVENTIONAL

Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
Matching Placebo	Placebo	Placebo identical to metformin
Metformin	Metformin	Metformin 1000 mg twice a day

Primary Outcome Measures

Name	Time	Method
Change in Score of the Alzheimer's Disease Assessment Scale-cognitive Subscale (ADAS-cog)	12 months	The ADAS-cog is an aggregate for several cognitive tests intended to provide a global cognitive score and consists of 11 tasks. The tasks (and corresponding score range)) are Word Recall (0-10), Naming (0-4), Commands (0-5), Constructional Praxis (0-5) Ideational Praxis (0-5), Orientation (0-8), Word Recognition (0-12), Language (0-5), Word Finding Difficulty (0-5), and Remembering Test Instructions (1-5). The range of aggregate scores (sum of scores) is 1 to 69, with higher scores meaning worse cognitive performance. The change was calculated subtracting the baseline score from the final visit score.
Change in Total Recall Score in the Selective Reminding Test	12 months	The Selective Reminding Test measures verbal learning and delayed recall through a multiple-trial list-learning paradigm. Patients are presented aurally with a list of 12 words for trial 1 and are asked to recall as many as possible. For trials 2-6, there is a selective presentation of only those words not recalled on the previous trial. Trial 7 is similar to the other trials but is assessed after an 11-minute delay. The score for the selective reminding test is the unweighted average of seven individual study results (min=0 and max=84) Higher scores indicate a better cognitive performance. The total recall score from the first visit was subtracted from that of the last visit to calculate the change in score (total words recalled).

Secondary Outcome Measures

Name	Time	Method
Change in Relative Glucose Uptake (rCMRg) in the Posterior Cingulate-precuneus.	12 months	Change in relative glucose uptake (rCMRgl) in the posterior cingulate-precuneus measured with subscale (ADAS-Cog) from brain \[18\]F-labeled 2-deoxy-2-fluoro-D-glucose (FDG) positron emission tomography (PET). The unit for rCMRgl is %. The results presented are absolute differences in rCMRgl, presented in % units; the change was calculated subtracting the baseline rCMRgl from the follow-up rCMRgl