Effect of Probiotic Supplementation on Cognitive Function and Metabolic Status in Alzheimer's Disease: A Randomized, Double-Blind and Controlled Trial
Authors: Ebrahim Kouchaki
Zatollah Asemi
Elmira Akbari
Fereshteh Bahmani
Omid Reza Tamtaji
Gholam Ali Hamidi
Reza Daneshvar Kakhaki
Mahmoud Salami
Journal: Frontiers in aging neuroscience (2016)
Discipline: NEUROSCIENCE & BEHAVIOR
Keywords: Alzheimer's disease; clinical trial; cognitive function; metabolic status; probiotic.
Affiliations: Physiology Research Center, Kashan University of Medical Sciences Kashan, Iran., Research Center for Biochemistry and Nutrition in Metabolic Diseases, Kashan University of Medical Sciences Kashan, Iran., Department of Neurology, School of Medicine, Kashan University of Medical Sciences Kashan, Iran.

Abstract:  Alzheimer's disease (AD) is associated with severe cognitive impairments as well as some metabolic defects. Scant studies in animal models indicate a link between probiotics and cognitive function. This randomized, double-blind, and controlled clinical trial was conducted among 60 AD patients to assess the effects of probiotic supplementation on cognitive function and metabolic status. The patients were randomly divided into two groups (n = 30 in each group) treating with either milk (control group) or a mixture of probiotics (probiotic group). The probiotic supplemented group took 200 ml/day probiotic milk containing Lactobacillus acidophilus, Lactobacillus casei, Bifidobacterium bifidum, and Lactobacillus fermentum (2 × 109 CFU/g for each) for 12 weeks. Mini-mental state examination (MMSE) score was recorded in all subjects before and after the treatment. Pre- and post-treatment fasting blood samples were obtained to determine the related markers. After 12 weeks intervention, compared with the control group (-5.03% ± 3.00), the probiotic treated (+27.90% ± 8.07) patients showed a significant improvement in the MMSE score (P &lt;0.001). In addition, changes in plasma malondialdehyde (-22.01% ± 4.84 vs. +2.67% ± 3.86 μmol/L, P &lt;0.001), serum high-sensitivity C-reactive protein (-17.61% ± 3.70 vs. +45.26% ± 3.50 μg/mL, P &lt;0.001), homeostasis model of assessment-estimated insulin resistance (+28.84% ± 13.34 vs. +76.95% ± 24.60, P = 0.002), Beta cell function (+3.45% ± 10.91 vs. +75.62% ± 23.18, P = 0.001), serum triglycerides (-20.29% ± 4.49 vs. -0.16% ± 5.24 mg/dL, P = 0.003), and quantitative insulin sensitivity check index (-1.83 ± 1.26 vs. -4.66 ± 1.70, P = 0.006) in the probiotic group were significantly varied compared to the control group. We found that the probiotic treatment had no considerable effect on other biomarkers of oxidative stress and inflammation, fasting plasma glucose, and other lipid profiles. Overall, the current study demonstrated that probiotic consumption for 12 weeks positively affects cognitive function and some metabolic statuses in the AD patients. Clinical trial registration: http://www.irct.ir/, IRCT201511305623N60. 

Retracted: No

PubPeer comments:
 Authors cannot use a same miR-NC as negative control in miRNA mimic or inhibitor transfection experiment, because miRNA mimic is double-strand RNA while inhibitor is single-strand RNA. ![file] , 
 We thank Takifugu Stictonotusu2019s comment about our work. The miR-425 mimic, miRNA mimic negative control and miR-425 inhibitor and miRNA inhibitor negative control were obtained from RiboBi (China). We conducted our experiments using miR-425 mimic inhibitor and the corresponding negative controls. We abbreviated miRNA mimic negative control to miR-NC in miR-425 mimic transfecting assays. We abbreviated miRNA inhibitor negative control to miR-NC in miR-425 inhibitor transfecting assays. ,