Background: Diabetes mellitus is associated with cognitive deficits in humans and animals. These deficits are paralleled by neurophysiological and structural changes in brain. In diabetic animals, impairments of spatial learning, memory, and cognition occur in association with distinct changes in hippocampus, a key brain area for many forms of learning and memory and are particularly sensitive to changes in glucose homeostasis. However, the multifactorial pathogenesis of diabetic encephalopathy is not yet completely understood. Apoptosis plays a crucial role in diabetes-induce neuronal loss in hippocampus. Methods: The effects of diabetes on hippocampus and cognitive/behavioral dysfunctions in experimental models of diabetes are reviewed, with a focus on the negative impact on increased neuronal apoptosis and related cellular and molecular mechanisms. Results: Of all articles that were assessed, most of the experimental studies clearly showed that diabetes causes neuronal apoptosis in hippocampus through multiple mechanisms, including oxidative stress, inhibition of caspases, disturbance in expression of apoptosis regulator genes, as well as deficits in mitochondrial function. The balance between pro-apoptotic and anti-apoptotic signaling may determine the neuronal apoptotic outcome in vitro and in vivo models of experimental diabetes. Conclusions: Dissecting out the mechanisms responsible for diabetes-related changes in the hippocampal cell apoptosis helps improve treatment of impaired cognitive and memory functions in diabetic individuals.

Helicobacter pylori infection is a common health problem related to many gastrointestinal disorders. This study aims to estimate the total and age specific prevalence of Helicobacter Pylori infection in Iran. We systematically reviewed all national and international databases and finally identified 21 studies were eligible for meta-analysis. Each of them were assigned a quality score using STROBE checklist. Due to significant heterogeneity of the results, random effects model was used to estimate the pooled prevalence and 95% confidence interval of Helicobacter Pylori infection. All statistical analyses were performed using STATA. V11 software. The pooled prevalence (95% confidence interval) of Helicobacter Pylori infection among all population, children and adults were estimated as 54% (53%- 55%), 42% (41%- 44%) and 62% (61%- 64%) respectively. Helicobacter Pylori, has infected more than half of Iranian people during the last decade. Preventive strategies as well as taking into account this infection during clinical visits should be emphasized to reduce its transmission and prevalence within the community.