Alzheimer's disease (AD) is the most common dementia and the trigger of its pathological cascade is widely believed to be the overproduction and accumulation of β-amyloid protein (Aβ) in the affected brain. However, effective AD remedies are still anxiously awaited. Recent evidence suggests that curcumin may be a potential agent for AD treatment. In this study, we used 5×FAD transgenic mice as an AD model to investigate the effects of curcumin on AD. Our results showed that curcumin administration (150 or 300 mg/kg/day, intragastrically, for 60 days) dramatically reduced Aβ production by downregulating BACE1 expression, preventing synaptic degradation, and improving spatial learning and memory impairment of 5×FAD mice. These findings suggest that curcumin is a potential candidate for AD treatment.

Background:Early diagnosis assumes a vital role in an effective treatment of Alzheimer's disease (AD). Most of the current studies can only make an AD diagnosis after the manifestation of typical clinical symptoms. The present study aimed to investigate typical and other biomarkers of AD to find a possible early biomarker.Methods:A total of 14 5XFAD mice (at 3 and 6 months old), with 14 age-matched wild-type (WT) mice as control, were enrolled in this case-control study. Morris water maze test was performed to evaluate the cognitive function; buried food pellet test and olfactory maze test were employed to investigate the olfactory function; immunofluorescence to detect amyloid deposition and positron emission tomography to examine 2-deoxy-2-(18 F) fluoro-D-glucose ([18 F]-FDG) uptake in the hippocampus and cerebral cortex.Results:With the increasing age, cognitive performance (P = 0.0262) and olfactory function were significantly deteriorated (day 1 P = 0.0012, day 2 P = 0.0031, day 3 P = 0.0160, respectively) and the (18 F)-FDG uptake was markedly decreased in multi-cerebral regions including the olfactory bulb (P < 0.0001), hippocampus (P = 0.0121), and cerebral cortex (P < 0.0001). Of note, in 3-month-old 5XFAD mice, a significant decline of (18 F)-FDG uptake in the olfactory bulb was found when compared with that of age-matched WT mice (P = 0.023) while no significant difference was present when the uptakes in other cerebral regions were compared.Conclusions:The decline of (18 F)-FDG uptake in the olfactory bulb occurs earlier than other incidents, serving as an earlier in vivo biological marker of AD in 5XFAD mice and making early diagnosis of AD possibly.

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