Establishing the feasibility and preliminary efficacy of a health belief model based educational training program on health belief perceptions and dementia-preventive behaviors in people with type 2 diabetes.

This quasi-experimental study evaluated feasibility and preliminary efficacy of dementia-preventive educational training intervention program based on the health belief model for improving perceived health beliefs and dementia-preventive behaviors among people with type 2 diabetes mellitus. Two community hospitals with 72 eligible participants were chosen from 12 local institutions using simple random sampling method. One hospital (22 patients) was allocated to dementia-preventive educational training intervention, and the other hospital (23 patients) was allocated to control intervention (using simple random sampling). Primary study outcome was feasibility, and secondary outcomes were changes in dementia prevention behaviors and health belief perceptions. Recruitment rate was 62.5% (45/72) and 22 patients in each group totally completed outcome measures and attended sessions, indicating feasibility of the intervention and study design. There were no significant differences between groups at baseline. After training, participants in the intervention group had significantly higher scores than control group in prevention behaviors and perceptions of health beliefs. The intervention group experienced significant with-group changes in outcomes. Results show that conducting a subsequent fully powered experimental study is feasible, and the intervention has promising efficacy.

Perception of benefits and barriers associated with dementia prevention behaviors among people with diabetes.

Type 2 diabetes mellitus is a risk factor for developing dementia and a public health concern around the world. Identifying any predictive factors associated with diabetes-related dementia prevention behaviors are of value in helping to prevent dementia. From six community hospitals in Chiang Mai, Thailand, 182 people aged 30-60 years were enrolled in a cross-sectional study and completed a written questionnaire on dementia prevention behaviors and perceptions of health beliefs. Multiple linear regression analysis was applied to determine possible associations between dementia prevention behaviors and health belief perceptions. A high level of preventive behavior was associated with high perceptions of the benefits of, and barriers to, dementia prevention and longer duration of patients' diabetes. Findings indicate the predictive role of the two factors in the perception of health beliefs about dementia prevention behaviors among the participants. Although further testing with different samples and in different locations is warranted, education programs for health practitioners that integrate the findings of this study would be beneficial to improvement of dementia prevention behaviors in people with diabetes.

DPP-4 inhibitor and PPARγ agonist restore the loss of CA1 dendritic spines in obese insulin-resistant rats.

BACKGROUND AND AIMS: Obesity induced by high-fat diet (HFD) impaired brain insulin receptor function, caused cognitive decline as well as reduced dendritic spine density. Previous studies suggested that dipeptidyl peptidase IV (DPP-4) inhibitor and peroxisome proliferator-activated receptor-gamma (PPARγ) agonist exerted the neuroprotective effects in obese insulin-resistant rats. However, the effects of these drugs on dendritic spines in obese insulin-resistant rats have not yet been investigated. In the present study, we determined the effects of DPP-4 inhibitor and PPARγ agonist on dendritic spines density of obese insulin-resistant rats caused by HFD. METHODS: Male Wistar Rats were divided into two groups. Animals in each group were fed with normal diet (ND) or HFD for 12 weeks. After then, rats in each group were subdivided into three subgroups to receive either vehicle or vildagliptin (3 mg/kg/day) or pioglitazone (10 mg/kg/day) for 3-4 weeks. At the end of the experiment, the metabolic parameters and density of dendritic spines in CA1 hippocampus were determined. RESULTS: We found that HFD-fed rats caused peripheral insulin resistance as well as the reduction of the density of dendritic spines in CA1 hippocampus. Treatment with both DPP-4 inhibitor and PPARγ agonist in HFD-fed rats improved insulin sensitivity as well as increased the number of dendritic spines in CA1 hippocampus. Moreover, both drugs have equally improved this deterioration. CONCLUSION: Our findings indicate that DPP-4 inhibitor and PPARγ agonist restored the reduction of dendritic spines caused by HFD, suggesting the beneficial roles of DPP-4 inhibitors and PPARγ agonists in neurodegenerative disorders.

Combined therapy of iron chelator and antioxidant completely restores brain dysfunction induced by iron toxicity.

BACKGROUND: Excessive iron accumulation leads to iron toxicity in the brain; however the underlying mechanism is unclear. We investigated the effects of iron overload induced by high iron-diet consumption on brain mitochondrial function, brain synaptic plasticity and learning and memory. Iron chelator (deferiprone) and antioxidant (n-acetyl cysteine) effects on iron-overload brains were also studied. METHODOLOGY: Male Wistar rats were fed either normal diet or high iron-diet consumption for 12 weeks, after which rats in each diet group were treated with vehicle or deferiprone (50 mg/kg) or n-acetyl cysteine (100 mg/kg) or both for another 4 weeks. High iron-diet consumption caused brain iron accumulation, brain mitochondrial dysfunction, impaired brain synaptic plasticity and cognition, blood-brain-barrier breakdown, and brain apoptosis. Although both iron chelator and antioxidant attenuated these deleterious effects, combined therapy provided more robust results. CONCLUSION: In conclusion, this is the first study demonstrating that combined iron chelator and anti-oxidant therapy completely restored brain function impaired by iron overload.

DPP4-inhibitor improves neuronal insulin receptor function, brain mitochondrial function and cognitive function in rats with insulin resistance induced by high-fat diet consumption.

High-fat diet (HFD) consumption has been demonstrated to cause peripheral and neuronal insulin resistance, and brain mitochondrial dysfunction in rats. Although the dipeptidyl peptidase-4 inhibitor, vildagliptin, is known to improve peripheral insulin sensitivity, its effects on neuronal insulin resistance and brain mitochondrial dysfunction caused by a HFD are unknown. We tested the hypothesis that vildagliptin prevents neuronal insulin resistance, brain mitochondrial dysfunction, learning and memory deficit caused by HFD. Male rats were divided into two groups to receive either a HFD or normal diet (ND) for 12 weeks, after which rats in each group were fed with either vildagliptin (3 mg/kg/day) or vehicle for 21 days. The cognitive function was tested by the Morris Water Maze prior to brain removal for studying neuronal insulin receptor (IR) and brain mitochondrial function. In HFD rats, neuronal insulin resistance and brain mitochondrial dysfunction were demonstrated, with impaired learning and memory. Vildagliptin prevented neuronal insulin resistance by restoring insulin-induced long-term depression and neuronal IR phosphorylation, IRS-1 phosphorylation and Akt/PKB-ser phosphorylation. It also improved brain mitochondrial dysfunction and cognitive function. Vildagliptin effectively restored neuronal IR function, increased glucagon-like-peptide 1 levels and prevented brain mitochondrial dysfunction, thus attenuating the impaired cognitive function caused by HFD.

PPARγ agonist improves neuronal insulin receptor function in hippocampus and brain mitochondria function in rats with insulin resistance induced by long term high-fat diets.

We previously demonstrated that a high-fat diet (HFD) consumption can cause not only peripheral insulin resistance, but also neuronal insulin resistance. Moreover, the consumption of an HFD has been shown to cause mitochondrial dysfunction in both the skeletal muscle and liver. Rosiglitazone, a peroxizome proliferator-activated receptor-γ ligand, is a drug used to treat type 2 diabetes mellitus. Recent studies suggested that rosiglitazone can improve learning and memory in both human and animal models. However, the effects of rosiglitazone on neuronal insulin resistance and brain mitochondria after the HFD consumption have not yet been investigated. Therefore, we tested the hypothesis that rosiglitazone improves neuronal insulin resistance caused by a HFD via attenuating the dysfunction of neuronal insulin receptors and brain mitochondria. Rosiglitazone (5 mg/kg · d) was given for 14 d to rats that were fed with either a HFD or normal diet for 12 wk. After the 14(th) week, all animals were euthanized, and their brains were removed and examined for insulin-induced long-term depression, neuronal insulin signaling, and brain mitochondrial function. We found that rosiglitazone significantly improved peripheral insulin resistance and insulin-induced long-term depression and increased neuronal Akt/PKB-ser phosphorylation in response to insulin. Furthermore, rosiglitazone prevented brain mitochondrial conformational changes and attenuated brain mitochondrial swelling, brain mitochondrial membrane potential changes, and brain mitochondrial ROS production. Our data suggest that neuronal insulin resistance and the impairment of brain mitochondria caused by a 12-wk HFD consumption can be reversed by rosiglitazone.