Cognitive Function and Cue-Reactivity Study
Condition: Cognitive Performance; Food Cravings
Study type: Observational

Summary: 
      We are interested in testing differences in cognitive function and food reactivity at various
      time points in individuals following low and high carbohydrate diets. We wish to achieve an
      understanding of these time-specific differences using repeated measures analysis of variance
      (ANOVA), with diet condition (low vs. high carbohydrate) as a between subject factor and time
      as a within-subject factor.
    

Detailed description: 
      Participants will be recruited from the parent study The Safety and Efficacy of Low and High
      Carbohydrate Diets. Participants will attend one 30-minute training session to learn the
      computer tasks and rate food desirability. Participants will rate their desire to eat "24"
      foods on a "9"-point Likert scale (e.g., 1 = do not desire at all; 5 = neutral, neither
      desire nor not desire; 9 = desire extremely). These ratings will be used to establish
      emotionally salient and neutral cues for the computerized tests (i.e., Cue Reactivity and
      Stroop test) used during the study.

      Each individual will participate on separate occasions in one 45-60 minute testing session
      before onset of treatment (week 0), and four 45-60 minute testing sessions that coincide with
      treatment assessments in the approved study (weeks 12, 26, 54). Testing will be conducted one
      and a half hours following consumption of a standard snack to ensure that all participants
      are in the same metabolic state. Participants will complete three consecutive computerized
      tests in the following order: 1) Continual Performance Test (CPT), 2) Stroop test, 3) Cue
      Reactivity Test. Based on a previous study showing impairments in cognitive function one week
      after initiation of a low carbohydrate diet, participants will also complete a 5-minute
      cognitive task (e.g., Continual Performance Task) one and four weeks after modifications in
      eating have begun. On these weeks, participants will be given a small snack prior to the
      group meeting. Testing will occur at the conclusion of weekly group meetings, ensuring that
      participants have abstained from food for approximately one and half hours.

      The 15 minute cue reactivity test consists of three cue trials that vary only in terms of the
      cue presented (one neutral non-food cue, one neutral food cue, and one emotionally salient
      food cue). The order of these trials will be presented in a counter-balanced
      order.Participants will complete a VAS questionnaire, rating their feelings of hunger,
      craving, and anxiety. Participants will insert dental rolls prior to each of three,
      five-minute cue-presentation trials. While participants insert the dental rolls, the
      experimenter will place the relevant cue on a platter. This platter will have a divider/
      barrier attached to it that obstructs the cue from the participant's view while the
      experimenter is in the room. After the rolls are inserted and the cue is placed on the
      platter, the experimenter will leave the room, and rotate the platter via remote control
      until the cue is in clear view of the participant.5-minute psychophysiologic data (i.e.,
      heart rate, skin conductance) acquisition will begin as the platter is being rotated.
      Participants will be instructed via audiotape to focus their attention on the cue, imagine
      picking it up, smelling it, and tasting it, etc. At the end of this 5-minute interval, blood
      pressure measures will be taken.Participants will remove the dental rolls and place them in a
      plastic zip-lock bag.The experimenter will return to the room and ask the participant to
      complete the post-trial VAS questionnaire, rating their feelings of hunger, craving, and
      anxiety. Then participants will be provided with one ounce of water.
    

Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        all participants who took part in the Safety and Efficacy of Low and High Carbohydrate
        Diets study
      
Biospecimen description: 
      salivary cortisol