Project Summary: Suicide is the 10th leading cause of death in the United States with the national economic
costs of suicide approximated to be $53 billion annually. While suicide’s causes are complex, suicide clusters in
families and it is widely hypothesized that interactions between an underlying genetic predisposition and
environmental factors are in suicide’s causal pathway. We recently reported a heightened risk of suicide
following short-term exposure to fine particulate matter and nitrogen dioxide among all suicides in Salt Lake
County, Utah from 2000-2010. Complementary studies investigating the relationship between weather and
suicide have found that suicide risk increases following exposure to excessive heat, solar radiation and draught.
To date, studies have largely focused on the effects of single air pollutants or weather variables on suicide.
Thus, complex mixtures, which more realistically reflect a person’s daily exposure to ambient air pollution and
weather, have not been examined in regards to suicide. In addition, the underlying characteristics that
influence a person’s vulnerability to suicide following exposure to air pollutants and weather variables are
largely unknown yet their recognition is critical for developing effective interventions. The goals of the
proposed study are to 1) investigate thoroughly the gaps in our current knowledge of the individual, additive
and combined effects of multiple short-term environmental exposures (i.e. ambient air pollutants and weather
variables) on suicide risk, 2) identify the demographic, clinical, and familial characteristics that increase a
person’s susceptibility to suicide following short-term exposure to ambient air pollution and weather, and 3)
identify and characterize genetic variants that interact with short-term ambient air pollution and weather to
increase suicide risk. We are uniquely positioned at the University of Utah to carry out the proposed work. Data
resources already available to our research team include molecular data from >5,500 cases (Illumina
Psycharray data; whole genome sequence data is available on a subset of 665 cases). Clinical and demographic
information is available from the Utah State Office of the Medical Examiner and the Utah Population Database
(UPDB). The UPDB includes multi-generation genealogical records, demographic data, vital records data,
information on early life conditions, and current medical information on ~11 million individuals in Utah. We
will use a nested case-control design analyzed in a multi-exposure Bayesian framework to quantify the effects
of multiple environmental exposures and identify underlying individual-level and familial susceptibilities.
Gene-environment interactions will be investigated using case-only and case-crossover study designs. Study
results may lead to the development of clinical, educational and/or pharmacological interventions for suicide,
targeted at high-risk individuals.