  A large body of work links traumatic brain injury (TBI) in adulthood to the
onset of Alzheimer's disease (AD). AD is the chief cause of dementia, leading
to reduced cognitive capacity and autonomy and increased mortality risk. More
recently, researchers have sought to investigate whether TBI experienced in
early-life may influence trajectories of cognitive dysfunction in adulthood. It
has been speculated that early-life participation in collision sports may lead
to poor cognitive and mental health outcomes. However, to date, the few studies
to investigate this relationship have produced mixed results. We propose to
extend this literature by conducting a prospective study on the effects of
early-life participation in collision sports on later-life cognitive health
using the Swedish Adoption/Twin Study on Aging (SATSA). The SATSA is unique in
its sampling of monozygotic and dizygotic twins reared together (respectively
MZT, DZT) and twins reared apart (respectively MZA, DZA). The proposed analysis
is a prospective study of 660 individuals comprised of 270 twin pairs and 120
singletons. Seventy-eight (11.8% individuals reported participation in
collision sports. Our primary outcome will be an indicator of cognitive
impairment determined by scores on the Mini-Mental State Examination (MMSE). We
will also consider several secondary cognitive outcomes including verbal and
spatial ability, memory, and processing speed. Our sample will be restricted to
individuals with at least one MMSE score out of seven repeated assessments
spaced approximately three years apart. We will adjust for age, sex, and
education in each of our models.
