A Decentralized Study on Dietary Influences on Cognitive Functions

Study Overview
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Brief Summary
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The current study aims to investigate the cognitive effects of diet-induced blood glucose fluctuations on cognitive performance in healthy older adults over multiple days, taking advantage of the currently available techniques to continuously measure blood glucose levels and to assess cognitive performance in a real-life setting. In this fully decentralized study, subjects will undergo two times a three-day measurement period, where their blood glucose will be continuously measured by a minimally invasive sensor and where the cognitive performance is measured at multiple time points throughout a day using a short test battery administered on their mobile phone. In addition to receiving standardized breakfast and lunch meals, the subjects are administered a low-GI(Glycemic Index) or normal-GI(Glycemic Index) snack in the morning and afternoon.

Detailed Description
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The study has two main scientific objectives. First, the investigators aim to investigate the acute effect of a low versus high-GI snack taken mid-morning or mid-afternoon on cognition, appetite, alertness and mood. To this end the investigators will compare the pre-snack and  2-hour snack measurements of the two snacks. The investigators hypothesize that the low-GI(Glycemic Index) snack, due to a blunted and sustained PPGR, leads to better cognition, appetite and alertness ratings. Secondly, the investigators aim to explore how daily fluctuations in blood glucose are associated with cognition, mood, appetite and alertness in healthy older adults. To this end the investigators will conduct exploratory correlational analyses between blood glucose parameters, the behavioural outcomes, and subject characteristics.

Official Title
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A Decentralized Study on Dietary Influences on Cognitive Functions

Conditions
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Glucose Metabolism, Cognitive Function

Intervention / Treatment
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* Other: Intervention
* Other: Control


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Aged 50 - 65 years Own and use a smartphone that is capable to run the study applications (Android 4.4 or later, OS 12.0 or later) Adequate fluency in the English language to understand the inform consent process, study instructions and study assessments Sufficient vision and hearing to complete study procedures based on medical judgment Willing and able to participate and to give written consent to comply with study procedures Exclusion Criteria: Presence or history of a metabolic, neurological, or psychiatric disease Use of prescription or OTC medication that may influence gastrointestinal, metabolic or neurological functioning Any health, functional or lifestyle factor that in the judgement of the investigator may interfere with the ability to comply with study procedures and/or the generation of valid study data Known food allergies Use of illicit drugs Alcohol intake >1 units/day • BMI <18.5 or >30 kg/m² Are a member of the research team or their immediate family members. Immediate family member is defined as spouse, parent, child, or sibling, whether biological or legally adopted

Ages Eligible for Study
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Minimum Age: 50 Years
Maximum Age: 65 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Other
Allocation: Randomized
Intervention Model: Crossover Assignment
Interventional Model Description: The study will be carried out according to a decentralized, randomized, placebo controlled, double-blind, cross-over design.
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Experimental<br>Low-GI snack, administered at 10.00 and 16.00 during the test days | Other: Intervention<br>* The low GI snack is a biscuit with a Glycemic Index of 23.8 ± 3.3. The low GI snack contains plain flour, fibre, plant-based protein, vegetable oil and a low GI sweetener. The interventional snacks (control, experimental) are matched for caloric content.<br>|
| Active Comparator: Control<br>Normal GI snack, administered at 10.00 and 16.00 during the test days | Other: Control<br>* The normal GI snack is a biscuit with a Glycemic Index of 54.4 ± 6.3. The control snack is formulated using basic ingredients for a biscuit recipe consisting of all-purpose flour, butter, sugar, vanilla flavour, baking soda, egg and salt.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Spatial working Memory | Spatial working memory is measured using Dot Memory Task. During the task, participants are presented with a set of dots on a mobile screen for a brief period of time. Following a short delay, a second set of dots is presented, and participants are asked to determine whether any of the dots in the second set were also present in the first set. Participants respond by pressing a button to indicate whether the second set of dots was a match or a non-match to the first set. The task typically involves varying the number of dots in each set to determine the participant's working memory capacity. The primary outcomes are accuracy(%) and reaction speed in milliseconds. | 6 test days | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Subjective Cognitive ability | On a Visual Analog Scale that ranges from 0 to 100, where 0 represents Not at all and 100 indicates Very Much, the answer to the question regarding one's cognitive ability, 'I am feeling mentally sharp, is obtained. | 6 test days | 
| Subjective Alertness | On a Visual Analog Scale that ranges from 0 to 100, where 0 represents Not at all and 100 indicates Very Much, the answer to the question regarding one's alertness, I am feeling tired, is obtained. | 6 test days | 
| Subjective Mood | On a Visual Analog Scale that ranges from 0 to 100, where 0 represents Not at all and 100 indicates Very Much, the answer to the question regarding one's mood, I am feeling relaxed, is obtained. | 6 test days | 
| Subjective Appetite | On a Visual Analog Scale that ranges from 0 to 100, where 0 represents Not at all and 100 indicates Very Much, the answer to the question regarding one's appetite, I am feeling hungry, is obtained. | 6 test days | 
| Blood Glucose | Blood glucose is measured continuously through Freestyle Libre CGM (Continuous Glucose Monitor) for 11 days | 11 days | 
| Speed of processing | The speed of processing is measured using the Symbol Search Task. The task involves presenting participants with pairs of symbols on a screen and requiring them to match these pairs with other pairs displayed at the top of the screen. Two pairs of symbols are presented at the bottom of the screen, and participants are asked to quickly determine which of the two pairs matches the pairs displayed at the top of the screen. The task measures the median reaction time (in milliseconds) of correctly matched symbol pairs. Participants are given a brief interval of 200 milliseconds between each response and the following stimulus to complete the task. This task is used to assess how quickly individuals can process visual information and make accurate decisions. | 6 test days | 
| Sustained attention | Sustained attention is measured using a 3-min Psychomotor Vigilance Task (PVT). The outcome variables are the median reaction time (ms) of valid responses and the number of lapses (reaction time exceeding 500ms). | 6 Test days |