Reduced emotional responsiveness in individuals with marginal elevation in blood pressure within the normal range: Evidence from altered affect-modulated startle response

Reduced responsiveness to emotional stimuli (‘emotional dampening’) has been observed in normotensives with elevated blood pressure (BP) and hypertensives but it is not known whether this is due to aberrant responding to emotional information at the involuntary level and whether it is also associated with minimal elevations in BP in the normal range. In this study, we examined emotional dampening using the affect-modulated startle paradigm given its proven sensitivity to motivational states of approach and withdrawal, typically independent of conscious intentional control. Acoustically elicited startle eye-blink modulation was measured using electromyography of the orbicularis oculi muscle beneath the left eye in 59 healthy individuals while they viewed pleasant, unpleasant and neutral standardized pictures. The expected startle attenuation to pleasant pictures, and startle potentiation to unpleasant pictures, relative to neutral pictures, was found in people in the comparison (N = 29) but not elevated BP (N = 30) group. This finding was further supported by significant moderating effect (assessed using ANCOVA and sub-sample analysis) of BP on valence-startle amplitude relationship. The comparison BP group also showed slower latencies to response onset for pleasant stimuli compared to neutral and unpleasant, with no effect of valence in the elevated BP group. However, BP did not moderate the valence-onset latency relationship. Our findings indicate that previously reported emotional dampening associated with elevated BP extends to reduced involuntary emotional reactivity and to individuals with even minimal BP elevations (i.e. higher but still within the normal range). Future research needs to confirm these findings in hypertensive individuals, preferably using within-subjects designs.