My research focuses on population-based studies of environmental, occupational, genetic (and gene-environment interactions) and lifestyle risk and protective factors for neurodegenerative diseases, specifically Parkinson’s disease and dementias/cognitive impairment; cancers and cardiovascular disease. I have a special research interest in Hispanic/Latino and low-income populations and in developing educational interventions aimed at childhood obesity prevention.

Select Papers



Meta-analysis concluding that the synthesis of evidence from 40 years of epidemiologic literature supports an association between
brain cancer and farming with its potential for exposure to chemical pesticides

Editorial for special issue of the journal Cancers "Environmental Carcinogens and Cancer Risk"

Study showing that consumption of water from private wells located in areas with documented historical agricultural pesticide use and presumably contaminated with pesticides is associated with an increased Parkinson’s disease risk.

A gene-environment analysis which examined whether PD risk depended on the combined presence of alpha-synuclein gene polymorphisms, pesticide exposures, and smoking, and whether effects varied by age-of-onset.

Study associating components of ambient air pollution (O3, PM2.5 and NO2) with cognitive dysfunction in healthy cognitively intact adults in Los Angeles.

Organochlorine chemicals, specifically DDT/DDE and PCBs, measured in the serum are not associated with breast cancer.

Lifestyle - Adventist Health Study-2 Cohort


Better observed physical function indicated by the Physical Performance Test (PPT) was associated with higher scores on processing speed tasks among healthy elderly adults: the Adventist Health Study-2. Associations between PPT and processing speed were stronger among participants who followed vegetarian dietary patterns. Click here for study reprint.

An exploratory study of vegetarian dietary patterns and cognitive function among elderly adults: the Adventist Health Study-2 did not support differences in processing speed, executive function, or memory/language abilities between vegetarians and non-vegetarians but did suggest that a more stable dietary pattern which was characteristic of vegetarians was associated with better memory/language abilities.

A long chain omega-3 score (comprised of DHA+EPA) was negatively correlated with MRI Ktrans values in the internal capsule of the brain, indicating higher omega-3 levels were associated with greater blood-brain barrier (BBB) integrity in this region. Trends were observed for a positive correlation between the long chain omega-3 score and both memory and language scores, but not with executive function, speed, or motor control. Click here for study reprint.

Study showing that a vegetarian diet modulates aging-associated circulating miRNAs in a sex-dependent manner of differential expression for certain miRNAs, which may be related in a beneficial manner to the healthspan.



Adverse childhood experiences (ACEs) and Multiple Sclerosis (MS) in a cohort study of adult Icelandic women.

Passive smoking exposure from home, work and other social settings is not convincingly protective of Parkinson's disease.

Vitamin D receptor polymorphisms, but not ultraviolet radiation (UVR), may modulate Parkinson's disease risk in a population highly exposed to UVR throughout lifetime.

A functional vitamin D receptor polymorphism is associated with cognitive decline in Parkinson's disease in a case-only analysis.

An experimental study showing that women who received a working memory training program showed significant improvements in their visuospatial and verbal working memory compared to controls.


Childhood obesity

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Compared to their classmates who did not participate in the intervention, LA Sprouts participants had significantly greater reductions in BMI z-scores and waist circumference and significant increases in dietary fiber intake.

LA Sprouts participants also had improvements in motivation to eat fruits and vegetables and a greater change in their perceptions of their ability to cook and garden.

Cardiovascular disease


Studies of subclinical atherosclerosis measured by carotid artery intima-media thickness and the clustering of risk factors in the metabolic syndrome on different aspects of cognitive function among middle-aged and older adults.

Markers of arteriosclerosis in the retinal microvasculature are associated with lower cognitive function.

Longitudinal analysis showing that brachial artery vasoreactivity and anatomical measures of atherosclerosis are correlated among subjects with coronary artery disease.