Uncovering sedentary behaviour: a comprehensive exploration of patterns and health effects among older adults with an intellectual disability

Abstract

Methods This thesis explores the sedentary behaviour (SB) levels of adults with an intellectual disability using diverse self-report methods and an objective measurement tool, to ultimately determine the effects of this SB on their physical heath. The study was conducted as part of the Intellectual Disability Supplement to the Irish Longitudinal Study on Aging (IDS-TILDA), a longitudinal study running in Ireland for over thirteen years which gathers health and lifestyle information every three years from a group of randomly selected Irish adults over 40 years of age, of all levels of intellectual disability, across all living circumstances to improve their health outcomes as they age. The IDS-TILDA study runs in parallel with the general population TILDA study so results may be directly compared. There were three main sources of data for this study, the Computer Assisted Personal Interview (CAPI), Pre-interview Questionnaire (PIQ) and the Health Fair. The CAPI was the primary source of self-reported information. It was a face-to-face personal interview between participants and/or a proxy and a trained researcher. Information on social, environmental, health, functional limitations and areas including physical activity (PA) and TV habits were collected. The PIQ was sent to participants to complete a week before the CAPI interview and consisted of questions on demographic, chronic health, medication and PA. Objective assessment of activity was also part of the data contributing to this study. As part of the objective health measurement of IDS-TILDA a device called an activPAL was fitted to gather sedentary and activity information on those participants who consented. Initially, a systematic review was executed to determine the prevalence of SB in the adult intellectual disability population and a literature review explored the effects of SB on health. The Systems of Sedentary Behaviour (SOS) framework was used to structure and frame results. Risk factors for SB were determined from the literature and examined. Objective measures of SB were investigated using several activPAL variables including total sedentary time, time spent lying down and time in various bouts of SB. In addition, inactivity was evaluated using steps, METs and Physical Activity level (PAL). The Barthel Index (BI) was used to examine the functional status of participants. Individual health conditions, the number of health conditions and a comorbidity index, Cumulative Index Rating Scale (CIRS-G) were used to assess participant?s health status. Comprehensive bivariate and multivariate investigations were completed on all data using regression models and decision trees. Data imputation was completed to improve the reliability of results.

Major findings High levels of SB are present in the intellectual disability population. The systematic review determined prevalence of SB was over 60% which compared to 67% observed in this study. Mostly people purported to watch between 1-3 hours of TV a day but overall using TV as a proxy for SB may not be the best choice especially for those with a more severe/profound level of intellectual disability. Novel risk factors for SB in the intellectual disability population were found including those who had difficulty walking 100 yards and those who got up later in the morning. People who were more active, as measured by activPAL, performed more sit-to-stand transitions and had more functional independence, while those who were less active had more cardiac health conditions. Participants who had elevated sedentary time observed associations with more endocrine conditions. More time spent in extended periods of SB saw a decrease in functional capacity and an increase in comorbidities present, particularly upper GI conditions. Conversely more time spent in shorter periods of SB was related to an increase in functional independence and the presence of decreased comorbidities, specifically a reduction in respiratory conditions, which is one of the leading causes of death in this population. Psychiatric conditions, which were the most common comorbidity observed in this study, were associated with more sedentary periods of up to two hours.