Methylene blue reduces Aβ levels and rescues early cognitive deficit by increasing proteasome activity


Year of Publication: 
Contact PI Name: 
Salvatore Oddo
Contact PI Affiliation: 
Department of Physiology, University of Texas Health Science Center, San Antonio, Texas, USA
David X. Medina, Antonella Caccamo
Primary Reference (PubMED ID): 
Funding Source:
Study Goal and Principal Findings: 

Promising results have emerged from a phase II clinical trial testing Methylene blue (MB) as a potential therapeutic for Alzheimer disease (AD), where improvements in cognitive functions of AD patients after 6 months of MB administration have been reported. Despite these reports, no preclinical testing of MB in mammals has been published, and thus its mechanism of action in relation to AD pathology remains unknown. In order to elucidate the effects of MB on AD pathology and to determine its mechanism of action, we used a mouse model (3xTg-AD) that develops age-dependent accumulation of Aβ and tau and cognitive decline. Here, we report that chronic dietary MB treatment reduces Aβ levels and improves learning and memory deficits in the 3xTg-AD mice. The mechanisms underlying the effects of MB on Aβ pathology appears to be mediated by an increase in Aβ clearance as we show that MB increases the chymotrypsin-and trypsin-like activities of the proteasome in the brain. To our knowledge, this is the first report showing that MB increases proteasome function and ameliorates AD-like pathology in vivo. Overall, the data presented here support the use of MB for the treatment of AD and offer a possible mechanism of action.

Therapeutic Agent

Therapeutic Information: 
Therapy Type:

Animal Model

Model Information: 
Model Type:
Strain/Genetic Background: 
Not Reported

Experimental Design

Is the following information reported in the study?: 
Power/Sample Size Calculation
Blinded for Treatment
Pharmacokinetic Measures
Toxicology Measures
Duration of Treatment
Age of Animal at the Beginning of Treatment
Sex as a Biological Variable
Number of Premature Deaths
Statistical Plan
Inclusion/Exclusion Criteria Included
Randomized into Groups
Blinded for Outcome Measures
Pharmacodynamic Measures
ADME Measures
Route of Delivery
Frequency of Administration
Age of Animal at the End of Treatment
Study Balanced for Sex as a Biological Variable
Number of Excluded Animals
Genetic Background
Conflict of Interest


Outcome MeasuredOutcome Parameters
  • Morris Water Maze
  • Histopathology
  • beta Amyloid Deposits
  • Neurofibrillary Tau Tangles
  • phospho-Tau
  • Biochemical
  • Amyloid Precursor Protein (APP)
  • APP-CTF83 (CTF alpha)
  • APP-CTF99 (CTF beta)
  • Adenosine Triphosphate (ATP)
  • Autophagosomal Marker LC3-I
  • Autophagosomal Marker LC3-II
  • Autophagy-Related Protein 7 (Atg7)
  • Beclin 1
  • Chymotrypsin-Like Activity
  • Trypsin-Like Activity
  • Peptidylglutamyl-Peptide Hydrolyzing (PDPH) Activity
  • Cytochrome C Oxidase Subunit 4 (COX IV)
  • Immunochemistry
  • Brain-beta Amyloid Peptide 40
  • Brain-beta Amyloid Peptide 42
  • Brain-beta Amyloid Deposits
  • phospho-Tau
  • Toxicology
  • Body Weight
  • General Health