Consumption of Potatoes, Avocados and Chickpeas and Cognitive Function in Older Adults

The Effect of Consumption of Potatoes, Avocados and Chickpeas Daily for 6 Months on Cognitive Function in Older Adults

Cognitive impairment is also a major risk factor for development of dementia later in life. Findings from the investigators studies suggest that the carotenoids, lutein and zeaxanthin may be important in cognitive function in the elderly. Avocados are a source of these carotenoids. The investigators study evaluates long-term avocado intervention as a treatment strategy for age-related cognitive impairment which could possibly prevent the onset of dementia. The investigators have also shown that lutein supplementation significantly improved verbal fluency scores in healthy older women. Based on these findings, the next logical step will be to investigate the ability of lutein and zeaxanthin contained in avocados to influence cognitive function in older adults. The investigators hypothesize that there will be a significant increase in cognitive function measures in older adults provided with meals containing 1 avocado/day at the end of 6 months, while no significant improvements will be observed in older adults given daily meals containing chickpeas and/or potatoes.

The proposed study is designed as a randomized, placebo controlled trial that tests the effects of 6 month supplementation with 1 avocado/day on cognitive function in older adults. Secondary analyses will determine whether baseline macular pigment (lutein in retina which canbe measured non invasivley) density predicts relative effectiveness of the intervention on cognitive function. Secondary outcomes include plasma biomarkers of oxidative stress and inflammation.

The study is designed as a placebo controlled trial that tests the effects of 6 month supplementation with daily meals containing 1 avocado or isocaloric amounts of chickpeas and/or potatoes on cognitive function in older adults. Subjects will be randomly assigned to one of the two groups. Secondary analyses will determine whether baseline macular pigment density (a non invasive measure of lutein and zeaxanthin in neural tissue) predicts relative effectiveness of the intervention on cognitive function. Secondary outcomes include plasma biomarkers of oxidative stress and inflammation. Participants will be recruited from community-dwelling men and women aged >50 yr, and potential participants will be screened to meet cognitive and functional criteria. Participants will be pre-screened by telephone; those who appear to meet criteria will undergo further screening. The study will include baseline (0 month), 3 and 6 month visits for study procedures, and monthly telephone calls. Given that there is a visible difference between the two interventions, a blinded study is not possible.

Inclusion Criteria:

• men and women age > 50 years
• BMI 19-30 kg/m2
• lutein intake of < 3 mg/d
• Docosahexaenoic acid intake < 250 mg/d (including supplements)
• Mini mental state exam (MMSE) score > 24
• Macular pigment density < 0.4 at 0.5 degrees
• Beck Depression Inventory < 20
• free of known disease
• BMI 19-29 kg/m2
• must be able to give written informed consent
• have normal hematologic parameters
• normal values of plasma albumin
• normal values for liver and kidney function (Appendix A)
• no use of carotenoid, n3 fatty acid, multivitamin/mineral, (> 2 months).

Exclusion Criteria:

• history of active small bowel disease or resection
• atrophic gastritis
• hyperlipidemia (LDL >120 mg/dL or triglycerides >150 mg/dL)
• hypertension (>150/90 mm Hg)
• diabetes, alcoholism (>2 drinks/d or 14 drinks/week)
• pancreatic disease
• anemia, and bleeding disorders (as determined by screening interview)
• avocado, potato or chickpea allergy
• pregnancy or lactation
• diseases that interfere with fat absorption, e.g. colitis, celiac disease, Crohn's disease, cystic fibroids (as determined by screening interview)
• medications that interfere with fat absorption, e.g. bile sequestrants (as determined by screening interview)
• use of antipsychotic, antimanic, anti-inflammatory, monoamine inhibitors, or dementia medications
• smoking or use of nicotine patches or gum (within past 6 months)
• use of drugs suspected of interfering with metabolism of blood clotting, e.g. warfarin (as determined by screening interview)
• subjects having extremely high dietary intakes of carotenoids as indicated by screening plasma values > NHANES 95th percentile for lutein/zeaxanthin, beta-carotene, cryptoxanthin, or lycopene
• stroke,head injury with loss of consciousness or seizures.
• Non English speaking: This is a small study with a sample size. Logistically and financially, getting materials translated for such a small study is not feasible.