The Effect of Intermittent Fasting on Brain Health

Functional near infrared spectroscopy (fNIRS) will be performed during the cognitive n-back task. fNIRS approach generates data that represent a relative change in oxygenated and deoxygenated hemoglobin measured over the cortical brain tissues. Neurovascular coupling will be evaluated as a change in oxy- and deoxy-hemoglobin between before and after completion of study.

Flicker light-induced dilation of the retinal vessels (percentage increase over baseline diameter) will be measured in the right or left eye of each study participant using the Dynamic Vessel Analyzer (DVA, IMEDOS Systems, Jena, Germany). The change in retinal vessel diameters is tracked and reported as a %change from baseline, before and after completion of study.

EEG signal will be collected to generate spectral data. These data will be used for comparison of EEG activity between before and after treatment. Units of measure - power spectral density. Reported as a %change from baseline, before and after completion of study.

Changes in microvascular endothelial function will be assessed using laser speckle contrast imaging (LSCI) in the hand using the flow mediated dilation approach. The change in skin perfusion is calculated and reported as a %change from baseline, between before and after completion of study.

The arterial stiffness will be measured using the pulse wave analysis approach (SphygmoCor, Atcor medical, Itasca IL, or similar). Analysis generated the augmentation index which will be used for comparison before and after completion of study.

Video recordings of the sublingual vasculature will be performed using the high definition video camera GlycoCheck (Microvascular health solutions). Data collected will include perfused boundary region (um), and will be used for comparison before and after completion of study.

Video recordings of the sublingual vasculature will be performed using the high definition video camera GlycoCheck (Microvascular health solutions). Data collected will include capillary density (mm/mm^2), and will be used for comparison before and after completion of study.

Video recordings of the sublingual vasculature will be performed using the high definition video camera GlycoCheck (Microvascular health solutions). Data collected will include red blood cell velocity (um/sec), and will be used for comparison before and after treatment.

The allocation of one's limited capacities to deal with an abundance of environmental stimulation will be measured in a combined "Flanker Inhibitory Control and Attention Test".Units of measure - score (from 0 to 10, bigger number is better). Reported as a %change from baseline.

The ability to store information until the amount of information to be stored exceeds one's capacity to hold that information will be measured using the "List Sorting Working Memory Test". Unit of measure - overall score (bigger number is better). Reported as a %change from baseline.

The capacity to plan, organize and monitor the executive of behaviors that are strategically directed in a goal-oriented manner will be measured using the "Dimensional Change Card Sort Test". Units of measure - score (from 0 to 10, bigger number is better). Reported as a %change from baseline.

Pattern Comparison Processing Speed Test assesses the amount of information that can be processed within a certain unit of time. Items are simple so as to purely measure processing speed. Units of measure - score (from 0 to 130, bigger number is better). Reported as a %change from baseline.

Weight and body composition using a bioimpedance scale and/or DXA scan. Reported as a %change from baseline, before and after completion of study

Dietary intake data for 24-hour recalls will be collected and analyzed using the Automated Self-Administered 24-hour (ASA24) Dietary Assessment Tool, version 2022, developed by the National Cancer Institute (https://epi.grants.cancer.gov/asa24). Estimated dietary intakes will be used to determine whether a participant was in a hypocaloric, eucaloric, or hypercaloric state during the intervention.

Total daily energy expenditure will be estimated using the Mifflin-St. Jeor equation. Estimated total daily energy expenditure will be used to determine whether a participant was in a hypocaloric, eucaloric, or hypercaloric state during the intervention.

Complete metabolic panel. Reported as a %change from baseline, before and after completion of study

Cognitive processes involved in the acquisition, storage and retrieval of new information, will be measured using the "Picture Sequence Memory Test". Unit of measure - overall score (bigger number is better). Reported as a %change from baseline.

Picture Vocabulary Test measures receptive vocabulary administered in a computer-adaptive test (CAT) format. Respondents select the picture that most closely matches the meaning of the word, before and after treatment. Unit of measure - overall score (bigger number is better). Reported as a %change from baseline.

Using fMRI, we will determine the changes in BOLD activation during standardized cognitive task. Reported as change in BOLD signal before and after intervention.