Evidence suggests that curcumin, the phytochemical agent in the spice turmeric, might be a potential therapy for Alzheimer's disease (AD). Its antioxidant, anti-inflammatory properties have been investigated extensively. Studies have also shown that curcumin can reduce amyloid pathology in AD. The underlying mechanism, however, is complex and is still being explored. In this study, we used the APPswe/PS1dE9 double transgenic mice, an AD model, to investigate the effects and mechanisms of curcumin in the prevention and treatment of AD. The water maze test indicated that curcumin can improve spatial learning and memory ability in mice. Immunohistochemical staining and Western blot analysis were used to test major proteins in β-amyloid aggregation, β-amyloid production, and β-amyloid clearance. Data showed that, 3 months after administration, curcumin treatment reduced Aβ40 , Aβ42 , and aggregation of Aβ-derived diffusible ligands in the mouse hippocampal CA1 area; reduced the expression of the γ-secretase component presenilin-2; and increased the expression of β-amyloid-degrading enzymes, including insulin-degrading enzymes and neprilysin. This evidence suggests that curcumin, as a potential AD therapeutic method, can reduce β-amyloid pathological aggregation, possibly through mechanisms that prevent its production by inhibiting presenilin-2 and/or by accelerating its clearance by increasing degrading enzymes such as insulin-degrading enzyme and neprilysin.

No abstract

The combination of GEPT extracts can reduce levels of endogenous Abeta peptide in APPV717I transgenic mice through the inhibition of PS1 activity rather than BACE1 and the promotion of IDE and NEP activity. Lower-expression of PS1 and over-expression of IDE or NEP may be helpful in potentially lowering brain Abeta levels in subjects with AD, and hence GEPT appears to offer potential that should be explored in AD.

No abstract

Recent studies have shown the therapeutic potential of curcumin in Alzheimer’s disease (AD). In 2014, our lab found that curcumin reduced Aβ40, Aβ42 and Aβ-derived diffusible ligands in the mouse hippocampus, and improved learning and memory. However, the mechanisms underlying this biological effect are only partially known. There is considerable evidence in brain metabolism studies indicating that AD might be a brain-specific type of diabetes with progressive impairment of glucose utilisation and insulin signalling. We hypothesised that curcumin might target both the glucose metabolism and insulin signalling pathways. In this study, we monitored brain glucose metabolism in living APPswe/PS1dE9 double transgenic mice using a micro-positron emission tomography (PET) technique. The study showed an improvement in cerebral glucose uptake in AD mice. For a more in-depth study, we used immunohistochemical (IHC) staining and western blot techniques to examine key factors in both glucose metabolism and brain insulin signalling pathways. The results showed that curcumin ameliorated the defective insulin signalling pathway by upregulating insulin-like growth factor (IGF)-1R, IRS-2, PI3K, p-PI3K, Akt and p-Akt protein expression while downregulating IR and IRS-1. Our study found that curcumin improved spatial learning and memory, at least in part, by increasing glucose metabolism and ameliorating the impaired insulin signalling pathways in the brain.

BackgroundDecline in verbal episodic memory is a core feature of amnestic mild cognitive impairment (aMCI). The delayed story recall (DSR) test from the Adult Memory and Information Processing Battery (AMIPB) discriminates MCI from normal aging and predicts its conversion to Alzheimer’s dementia. However, there is no study that validates the Chinese version of the DSR and reports cut-off scores in the Chinese population.MethodsA total of 631 subjects were screened in the memory clinics of Dongzhimen Hospital, Beijing University of Chinese Medicine, China. 249 were considered to have normal cognition (NC), 134 met diagnostic criteria for MCI according to the MCI Working Group of the European Consortium on Alzheimer's Disease, and 97 met criteria for probable Alzheimer’s disease (AD) according to the NINCDS/ADRDA criteria, 14 exhibited vascular dementia (VaD), and 50 had a diagnosis of another type of dementia. Receiver operating characteristic (ROC) curve analyses were used to calculate the story recall cutoff score for detecting MCI and AD. Normative data in the NC group were obtained as a function of age and education.ResultsIn this Chinese sample, the normative mean DSR score was 28.10 ± 8.54 in the 50–64 year-old group, 26.22 ± 8.38 in the 65–74 year-old group, and 24.42 ± 8.38 in the 75–85 year-old group. DSR performance was influenced by age and education. The DSR test had high sensitivity (0.899) and specificity (0.799) in the detection of MCI from NC using a cut-off score of 15.5. When the cutoff score was 10.5, the DSR test obtained optimal sensitivity (0.980) and specificity (0.938) in the discrimination of AD from NC. Cutoff scores and diagnostic values were calculated stratified by age and education.ConclusionsThe Chinese version of the DSR can be used as a screening tool to detect MCI and AD with high sensitivity and specificity, and it could be used to identify people at high risk of cognitive impairment.

Significant losses of synapses have been demonstrated in studies of Alzheimer's disease (AD), but structural and functional changes in synapses that depend on alterations of the postsynaptic density (PSD) area occur prior to synaptic loss and play a crucial role in the pathology of AD. Evidence suggests that curcumin can ameliorate the learning and memory deficits of AD. To investigate the effects of curcumin on synapses, APPswe/PS1dE9 double transgenic mice (an AD model) were used, and the ultra-structures of synapses and synapse-associated proteins were observed. Six months after administration, few abnormal synapses were observed upon electron microscopy in the hippocampal CA1 areas of the APPswe/PS1dE9 double transgenic mice. The treatment of the mice with curcumin resulted in improvements in the quantity and structure of the synapses. Immunohistochemistry and western blot analyses revealed that the expressions of PSD95 and Shank1 were reduced in the hippocampal CA1 areas of the APPswe/PS1dE9 double transgenic mice, but curcumin treatment increased the expressions of these proteins. Our findings suggest that curcumin improved the structure and function of the synapses by regulating the synapse-related proteins PSD95 and Shank1.

No abstract