Page 96 - 2020_01-Haematologica-web

P. Shah et al.
day. Sixty-one percent of subjects had a level of education equivalent to high school or superior. Seventy-two per- cent reported that they had a high level of competitiveness on the visit screening questionnaire.
Vasoconstriction due to mental stress
As determined from the photoplethysmogram, there was a significant drop in microvascular blood flow during both cognitive tasks (N-back and Stroop, P<0.0001) and the PA task (P<0.0001) (Figure 3). Figure 2 (signal 2) shows a typical response of vasoconstriction in one subject. The drop in microvascular blood flow from baseline was greater during the PA task than during the cognitive tasks. A similar vasoconstriction response was observed when the microvascular blood flow was assessed by laser- Doppler flowmetry. Subjects had higher anxiety scores
immediately after completing the tasks than at baseline (STAI Y-1, mean difference=6; P=0.0007). Eighty-five per- cent of patients with SCD and 75% of controls showed vasoconstriction compared to baseline during at least one cognitive task. Eighty-five percent of SCD patients and 87.5% of controls had decreases in mean blood flow dur- ing the PA task. There was no difference in the magnitude of responses between individuals with SCD and controls. Demographic variables such as age, gender, race, number of days from last menstruation, and laboratory values were not associated with the magnitude of the vasocon- striction response.
The Stroop test caused greater vasoconstriction than the N-back task, irrespective of the order in which the tests were presented (P=0.019) (Figure 3). Subjects who were randomized to perform the Stroop task first had greater
Figure 3. Microvascular blood flow under mental stress in all subjects. Significant vasoconstriction occurred during all mental stress tasks compared to baseline. Open diamonds represent group median values. SE: standard error of mean.
AB
Figure 4. Effect of error rate during mental stress tasks on blood flow. (A, B) Mean ± standard error (SE) of microvascular blood flow and accuracy scores in sublevels of the N-Back (zeroback, oneback, twoback and threeback) task (A) and Stroop (onestroop, twostroop and threestroop) (B).
86
haematologica | 2020; 105(1)