Clinical Research Directory

Long-Term Effects of Walnut Consumption on Brain Function

Rationale: Healthy foods, including mixed nuts, may improve brain function, which is essential for cognitive and metabolic health, and may contribute to improved food intake regulation. It is therefore important to investigate the specific effects of walnuts on cerebral blood flow responses before and after intranasal insulin administration, as well as their associated functional benefits. The investigators hypothesize that long-term walnut consumption improves vascular function and insulin-sensitivity in the brain, thereby enhancing cognitive performance and appetite control in abdominally obese men and women. Objective: The primary objectives are to investigate in abdominally obese adults the effects of 24-week walnut consumption on (regional) vascular function and insulin-sensitivity in the brain, while the investigators will also assess changes in cognitive performance and appetite-related brain reward activity (secondary objectives). Cerebral blood flow responses before (brain vascular function) and after the administration of intranasal insulin spray (brain insulin-sensitivity) will be quantified by the non-invasive gold standard magnetic resonance imaging (MRI)-perfusion method Arterial Spin Labeling (ASL). Study design: This intervention study will have a randomized, controlled parallel design. The total study duration will be 24 weeks. Study population: Fifty-five abdominally obese men and (postmenopausal) women (aged 45-75 years) without a history of cardiovascular diseases or complaints will participate. This study population is expected to have a decreased cerebral blood flow at baseline and are also at increased risk of cognitive impairment, allowing for improvement by the intervention. Intervention: Study participants will receive daily 50 g (about 15% of energy) of raw walnuts (walnut intervention) or no walnuts (control intervention) for 24 weeks. Main study parameters/endpoints: At baseline and after 24 weeks (follow-up), participants will visit the research facilities for assessments. The primary endpoint is the difference in the cerebral blood flow response before and after intranasal insulin administration between the walnut and control intervention. Cognitive performance will be assessed, while the investigators will also focus on appetite-related brain reward activity (secondary outcomes).

Timing and Resistance Exercise: Impact on Eating and Metabolism

Exercise timing (morning or evening) for optimal weight control is a research topic urgently addressed by scholars in the relevant field. Due to the better control of energy metabolism and physical activity levels in the morning, existing research on resistance exercise and eating behavior primarily focuses on experiments conducted in the morning, with only one study in the afternoon. No research has yet compared the potential differences between morning and evening resistance exercise. A one-year study aims to investigate the impact of morning and evening resistance exercise on physiological metabolism and eating behavior. Eighteen healthy male participants will be randomly assigned to a crossover design study, including AM exercise, PM exercise, and control (rest condition) trials. Variables including subjective appetite, appetite hormones (ghrelin, peptide YY), food preferences, ad libitum eating, dietary records, energy expenditure, and PBMCs circadian rhythm genes will be measured. This preliminary study through a multidimensional observation, the results will contribute to understanding the potential differences and mechanisms of morning and evening resistance exercise on physiological metabolism and eating behavior. In practical applications, conducting resistance exercise in the evening or at night aligns better with current lifestyles. The findings of this study can support the optimization of exercise benefits by validating the choice of exercise timing.