Too much of a good thing? Overexertion of self-control and dietary adherence in individuals with Type 2 diabetes.

OBJECTIVES: The resource model of self-control posits that self-control is a finite resource that can be depleted. Individuals with diabetes must continually restrict their diet, requiring self-control. As a result, dietary adherence is difficult, and lapses are common. People with diabetes who overexert self-control following a lapse may be especially likely to experience a subsequent relapse, as suggested by the resource model. This investigation used the resource model of self-control to test whether overexertion of dietary self-control following a lapse would be predictive of a subsequent relapse in dietary control. DESIGN: We tested this prediction in a daily diary study of 128 individuals with diabetes (Mage  = 66.12). METHODS: Participants' reports of their daily dietary adherence were used to define lapses in adherence, post-lapse adherence, and relapses. RESULTS: Individuals who overexerted self-control after a lapse were more likely to experience a subsequent relapse (OR = 3.276, p = .016) and to do so sooner (HR = 2.12, p = .023). CONCLUSIONS: People with diabetes may seek to compensate for a lapse in adherence by overexerting self-control, but doing so may deplete their self-control and increase the risk of a future relapse. Statement of contribution What is already known on this subject? The resource model of self-control posits that self-control is a limited resource that can be temporarily depleted. Numerous experimental studies have demonstrated support for this model showing that when participants are instructed to engage in a self-control task, they produce less self-control on a subsequent task. The majority of the existing studies are not conducted in naturalistic settings and do not use patient populations. What does this study add? This study is an ecologically valid test of the resource model of self-control. This study applies the resource model of self-control to a patient population.

Oral contraceptives and nicotine synergistically exacerbate cerebral ischemic injury in the female brain.

Oral contraceptives (OC) and smoking-derived nicotine (N) are known to synergistically increase the risk and severity of cerebral ischemia in women. Although it has been known for some time that long-term use of OC and nicotine will have an increased risk of peripheral thrombus formation, little is known about how the combination of OC and nicotine increases severity of brain ischemia. Recent laboratory studies simulating the conditions of nicotine exposure produced by cigarette smoking and OC regimen of women in female rats confirms that the severity of ischemic hippocampal damage is far greater in female rats simultaneously exposed to OC than to nicotine alone. These studies also demonstrated that the concurrent exposure of OC and nicotine reduces endogenous 17ß-estradiol levels and inhibits estrogen signaling in the brain of female rats. The endogenous 17ß-estradiol plays a key role in cerebrovascular protection in women during their pre-menopausal life and loss of circulating estrogen at reproductive senescence increases both the incidence and severity of cerebrovascular diseases. Therefore, OC and nicotine induced severe post-ischemic damage might be a consequence of lack of estrogen signaling in the brain. In the present review we highlight possible mechanisms by which OC and nicotine inhibits estrogen signaling that could be responsible for severe ischemic damage in females.

Periodic 17ß-estradiol pretreatment protects rat brain from cerebral ischemic damage via estrogen receptor-ß.

Although chronic 17ß-estradiol (E2) has been shown to be a cognition-preserving and neuroprotective agent in animal brain injury models, concern regarding its safety was raised by the failed translation of this phenomenon to the clinic. Previously, we demonstrated that a single bolus of E2 48 hr prior to ischemia protected the hippocampus from damage in ovariectomized rats via phosphorylation of cyclic-AMP response element binding protein, which requires activation of estrogen receptor subtype beta (ER-ß). The current study tests the hypothesis that long-term periodic E2-treatment improves cognition and reduces post-ischemic hippocampal injury by means of ER-ß activation. Ovariectomized rats were given ten injections of E2 at 48 hr intervals for 21 days. Hippocampal-dependent learning, memory and ischemic neuronal loss were monitored. Results demonstrated that periodic E2 treatments improved spatial learning, memory and ischemic neuronal survival in ovariectomized rats. Additionally, periodic ER-ß agonist treatments every 48 hr improved post-ischemic cognition. Silencing of hippocampal ER-ß attenuated E2-mediated ischemic protection suggesting that ER-ß plays a key role in mediating the beneficial effects of periodic E2 treatments. This study emphasizes the need to investigate a periodic estrogen replacement regimen to reduce cognitive decline and cerebral ischemia incidents/impact in post-menopausal women.

The relationship of perceived neighborhood social climate to walking in Hispanic older adults: a longitudinal, cross-lagged panel analysis.

OBJECTIVE: This study examines possible bidirectional relationships between neighborhood climate (i.e., perceived neighborhood social environment) and walking behavior across a 12-month period in older Hispanics. METHOD: A population-based sample of 217 community-dwelling older Hispanics in Miami, Florida, completed measures of perceived neighborhood climate and neighborhood walking, at two assessment time points (12 months apart). RESULTS: Structural equation modeling analyses revealed that neighborhood climate predicted subsequent walking 12 months later, such that more positive perceptions of neighborhood climate predicted more walking. Follow-up analyses revealed that older adults who resided in the top half of neighborhoods based on perceived neighborhood climate scores at initial assessment were 2.57 times as likely to have walked at least one block in the last week at follow-up, relative to older adults residing in neighborhoods whose climate was in the lower half. DISCUSSION: Perceptions of a more positive neighborhood social environment may promote walking in urban, older Hispanics.