The Acute Effect of a Walnut Intervention on Cognitive Performance, Brain Activation, and Serum Markers of Inflammation in Young Adults
Condition: Cognitive Change; Mood; Inflammatory Response; Brain Derived Neurotrophic Factor Level; Satiety
MeSH terms: Inflammation
Study type: Interventional

Summary: 
      This study investigates the effect of acute walnut consumption on the cognitive behaviour,
      mood, brain activation, and markers of inflammation in young adults. In a within subjects
      design participants will receive a 50 g walnut or placebo intervention in a randomised order
      with a one week washout between interventions.
    

Detailed description: 
      Participants will attend two test session days separated by a 7 day wash out period. The
      procedure on each day will be identical save for the intervention breakfast which will either
      be a walnut rich muesli containing 50g walnut and 50g mixed cereal ingredients (active
      intervention), or control muesli containing 100g mixed cereal ingredients (placebo
      intervention). The order of intervention will be randomised such that 50% of participants
      receive the active intervention during visit 1 and 50% during visit 2. Participants will be
      required to follow a low flavonoid diet for 48 hours in advance of testing and to fast (water
      only) for the final 12 hours of this period. The test day will be 8hrs in total starting at
      0830.

      Cognitive Measures: There will be four cognitive task battery sessions taking place at
      baseline, then 2, 4, and 6 hours following intervention. The cognitive battery will last for
      30 minutes and include:

        -  Auditory Verbal Learning Task (AVLT) - Participants hear and recall a list of 15 words
           on 8 occasions followed by a forced choice visual recognition task (10 minutes
           duration).

        -  Modified Attention Network Task (MANT) - Participants view different arrays of arrows
           displayed on a monitor and respond by indicating the direction of the arrow closest to a
           central fixation point (8 minutes duration).

        -  Switching Task - Participants view eight equally spaced radii of circle displayed in
           such a way that there are four equally spaced segments above and below a bold line.
           Stimulus digits selected from between 1 - 9 (excluding 5) appear in each segment in
           turn. Participants respond to digits above the bold line in terms of whether they are
           odd or even and below the bold line in terms of whether they are above or below the
           number 5 (10 minutes duration).

        -  PANAS-NOW - This measure of trait mood will be completed at the beginning and end of
           each task battery giving a total of 8 measurements across the day. Participants rate the
           extent to which they are experiencing 20 different emotions on a 5-point Likert scale
           ranging from 'very slightly' to 'very much' (1 minute duration).

      EEG: All participants will be tested in our dedicated lab within the Reading University
      Centre for Integrative Neuroscience and Neurodynamics using the Brain Products EEG system
      with 32 channel active electrode caps. At Baseline, 2, 4 and 6 hrs waveband PSD data will be
      recorded during all tasks with specific attention being paid to the theta bandwidth during
      the AVLT and gamma bandwidth during the executive function tasks. ERP data, anchored to each
      trial of the executive function tasks, will also be considered with specific attention being
      given to latency and strength of N1 and P3 peaks.

      Bloods: Participants will have bloods taken twice on each test visit with a draw being taken
      from each arm. The initial draw will be taken immediately prior to the baseline task battery
      and then immediately prior to either the 2, 4 or 6 hr session with the second draw time being
      randomised in such a way that 16 participants will have blood drawn at 2hrs, 16 at 4hrs, and
      16 at 6hrs. Following each draw, the blood samples will be left to clot for 30-60 minutes.
      The serum will be separated via centrifuge and stored at at -80°C until analysis is complete.
      Whole blood samples will not be stored at any point during the study. Blood serum will be
      analysed for anti-inflammatory ability, as well as levels of BDNF, a signalling protein known
      to be positively related to memory function. To determine possible mechanisms of action of
      walnut components through which the walnut polyphenols produce their beneficial effects,
      microglial cells from rats will be exposed to serum from participants in both walnut and
      placebo conditions prior to exposure to an inflammatory challenge (LPS). Markers of
      inflammation will then be assessed including extracellular release of nitric oxide (NO) and
      tumor necrosis factor-alpha (TNF-α) as well as intracellular levels of inducible nitrous
      oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). We will then determine if those subjects
      with the most protective serum in the cell model are those with the better cognitive
      performance.

      Appetite Measures: Ratings of subjective appetite and fullness will be taken using visual
      analogue scales after baseline, breakfast, and each of the remaining test sessions. As a
      further measure of satiety, weighted food measurements will be taken before and after
      consumption of the standard low flavonoid/PUFA lunch (given immediately after task battery
      session 3 at 1330) to ascertain total food consumption.
    

Intervention name(s): Control; 50 g Walnut
Intervention type(s): Other; Other
Intervention description(s): 100 grams breakfast cereal; 50 grams walnuts mixed with 50 gram breakfast cereal.
Allocation: Randomized
Intervention model: Crossover Assignment
Intervention model description: Participants will be assigned to both the walnut and control conditions in a randomised order.
Masking: Triple (Participant, Investigator, Outcomes Assessor)
Primary purpose: Basic Science
Keywords: Flavonoid; Omega 3 Fatty Acid