UNITE Project: understanding neurocognitive impairment after trauma exposure–study protocol of an observational study in Christchurch, New Zealand

INTRODUCTION: Our previous research has demonstrated significant cognitive effects of earthquake exposure 2–3 years following the Canterbury earthquake sequence of 2011. Such impairment has major implications for a population trying to recover, and to rebuild, a devastated city. This study aims to examine psychological, cognitive and biological factors that may contribute to subjective cognitive difficulties in a large group of individuals exposed to the Canterbury earthquake sequence. METHODS AND ANALYSIS: Two-hundred earthquake-exposed participants from an existing large cohort study (Christchurch Health and Development Study, CHDS) will be recruited. Inclusion is based on results of online screening of the CHDS cohort, using the Cognitive Failures Questionnaire. Individuals scoring the highest (n=100) and lowest (n=100), representing the highest and lowest levels of subjective cognitive impairment, are selected. Exclusions are: psychotic/bipolar disorders, serious substance/alcohol dependence, chronic medical conditions, pregnancy and previous serious head injury. Participants will undergo a half-day assessment including clinician-rated interviews, self-report measures, objective and subjective cognitive assessments, blood sample collection and physical measurements. The primary analysis will compare cognitive, psychological and biological measures in ‘high’ and ‘low’ subjective cognitive impairment groups. The study will have power (p<0.05, α=0.8) to show a difference between groups of 0.4 SD on any variable. ETHICS AND DISSEMINATION: Ethical approval for this study was granted by the New Zealand Health and Disability Ethics Committee. The online screening component of the study received ethical approval on 1 April 2021 (16/STH/188, PAF 7), and the main study (subsequent to screening) received approval on 16 August 2021 (Northern A 21/NTA/68). All participants provide written informed consent. Findings will be disseminated initially to the CHDS cohort members, the wider Canterbury community, and then by publication in scientific journals and conference presentations. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov Registry (NCT05090046).