Trial of Pistachio Consumption in Older Adults

The investigators will assess 6-month changes in the Mobile Toolbox (MTB) fluid cognition composite (FCC) score via MyCap. Participants will be instructed to install the MyCap app on their personal smartphones to complete the assessments. The FCC score considers the following domains (tests): associative memory (Face and Names), episodic memory (Arranging Pictures), working memory (Sequences), processing speed (Number-Symbol Match), and executive function (Arrow Matching for inhibitory control, Shape-Color Sorting for cognitive flexibility). The FCC score will be calculated by standardizing scores for each MTB test using means and standard deviations (SD) across the entire sample and averaging z-scores across the six tests (mean=0; SD=1). Higher FCC scores will indicate better cognitive function.

The investigators will assess 6-month changes in seated systolic and diastolic blood pressure (in mmHg).

The investigators will assess 6-month changes in total score for the "Life Satisfaction for the Third Age-Short Form" questionnaire, a validated self-rated 12-item assessment of successful aging and psychological well-being among older adults. Participants will be instructed to select an answer that most closely reflect their attitude towards each statement on a Likert scale from 1 (strongly disagree) to 6 (strongly agree). Scores may range from 6-72, in which a higher score indicates greater life satisfaction.

The investigators will assess 6-month changes in the Mobile Toolbox "Shape-Color Sorting" test as a measure of cognitive flexibility, a component of executive function (individual cognitive domain). Participants are primary scored on rate correct per second, using the number of correct trials per second as a derived score. Raw rate scores may range from 0-10, in which a higher score indicates better cognitive flexibility.

The investigators will assess 6-month changes in the Mobile Toolbox "Arrow Matching" test as a measure of inhibitory control, a component of executive function (individual cognitive domain). Participants are primary scored on rate correct per second, using the number of correct trials per second as a derived score. Raw rate scores may range from 0-10, in which a higher score indicates better inhibitory control.

The investigators will assess 6-month changes in the Mobile Toolbox "Faces and Names" test as a measure of associative memory (individual cognitive domain). The test consists of one encoding phase and three memory phases: Face Recognition, Name Recall, and Name Recognition (possible score range for each: 0-12). Total raw scores may range from 0-36, in which a higher score indicates better associative memory.

The investigators will assess 6-month changes in body weight (in kg).

The investigators will assess 6-month changes in lipid profiles, including total cholesterol, low-density lipoprotein cholesterol (Friedewald calculated), high-density lipoprotein cholesterol, and triglycerides. All lipids will be reported as mg/dL.

The investigators will assess 6-month changes in fasting blood glucose (in mg/dL).

The investigators will assess 6-month changes of insulin-like growth factor-1 in the blood (in ng/mL).

The investigators will assess 6-month changes of interleukin-6 in the blood (in pg/mL).

The investigators will assess 6-month changes in the Mobile Toolbox "Arranging Pictures" test as a measure of episodic memory (individual cognitive domain). This test scores the sum of adjacent pairs correctly placed across two trials. Raw scores range from 0-26 (14 images results in a maximum of 13 adjacent pairs correct per trial), in which a higher score indicates better episodic memory.

The investigators will assess 6-month changes in the Mobile Toolbox "Sequences" test as a measure of working memory (individual cognitive domain). This score is the total number of items (individual sequence) correctly answered. The possible raw score range is 0-30, in which a higher score indicates better working memory.

The investigators will assess 6-month changes in the Mobile Toolbox "Number-Symbol Match" test as a measure of processing speed (individual cognitive domain). The test includes 144 total items, with up to 16 successive screens of 9 items each presented, and examinees have 90 seconds to complete as many items as possible. This score is the total number of items correctly answered in 90 seconds. The possible raw score range is 0-144, in which a higher score indicates better processing speed.

The investigators will assess 6-month changes in waist circumference (in cm).

The investigators will assess 6-month changes in serum lutein (in µmol/L) as a marker of compliance with pistachio consumption. Participants in the pistachio group are expected to have increases in serum lutein levels, while participants in the usual group are expected to have no changes.

The investigators will assess 6-month changes in serum gamma tocopherol (mg/L) as a marker of compliance with pistachio consumption. Participants in the pistachio group are expected to have increases in serum gamma tocopherol levels, while participants in the usual group are expected to have no changes.