Blunted autonomic response to standing up and head-up tilt in individuals with intellectual disabilities
Previous research suggests individuals with intellectual disabilities (ID) may experience autonomic dysfunction, however this has not been thoroughly investigated. PURPOSE: To compare the autonomic response to standing up (active orthostasis) and head up tilt (passive orthostasis) in individuals with ID to a control group without ID. METHODS: Eighteen individuals with and 18 individuals without ID were instrumented with an ECG-lead and finger-photoplethysmography for continuous heart rate and blood pressure recordings. The active and passive orthostasis protocol consisted of 10 minutes supine rest, 10 minutes standing, 10 minutes supine recovery, 5 minutes head-up tilt at 70 degrees, followed by 10 minutes supine recovery. The last five minutes of each position was used to calculate hemodynamic and autonomic function (time- and frequency-domain heart rate and blood pressure variability measures and baroreflex sensitivity). RESULTS Individuals with ID had higher heart rate during baseline and recovery (p<0.05), and an attenuated hemodynamic (stroke volume, heart rate) and heart rate variability response to active and passive orthostasis (interaction effect p<0.05) compared to individuals without ID. Mean arterial pressure (MAP) was higher in individuals with ID at all timepoints. CONCLUSION Individuals with ID demonstrated altered hemodynamic and autonomic regulation compared to a sex- and age-matched control group, evidenced by a higher mean arterial pressure and a reduced response in parasympathetic modulation to active and passive orthostasis.