BackgroundPrevious studies on the relationship between blood pressure (BP) and psychological morbidity are conflicting. To resolve this confusing picture we examined the hypothesis that there is a non-linear relationship between panic and systolic BP (SBP) and explored the association of generalized anxiety symptoms with SBP.MethodWe used data from the population-based Nord-Trøndelag health study (HUNT) in which all 92 936 individuals aged ⩾20 years residing in one Norwegian county were invited to participate. Panic was assessed using one item from the anxiety subscale of the Hospital Anxiety and Depression Scale (HADS) and generalized anxiety with the remaining six items of this subscale. SBP was the mean of two measurements by an automatic device.ResultsA total of 64 871 respondents had SBP recorded (70%). Both unadjusted (n=61 408) and adjusted analyses provided evidence for a non-linear relationship between panic and SBP, represented by a U-shaped curve with a minimum prevalence of panic at around 140 mmHg. The relationship was strengthened after adjustment for confounders, with the quadratic term significantly associated with panic (p=0.03). Generalized anxiety symptoms were associated only with low SBP.ConclusionsThe U-shaped relationship between SBP and panic provides a unifying explanation for the separate strands of published literature in this area. The results support the hypothesis that high BP and panic disorder could share brainstem autonomic and serotonergic abnormalities. By contrast, generalized anxiety symptoms were more common only at lower BPs, suggesting that any biological link between panic and high BP does not extend to generalized anxiety.