New research – involving more than 1 million men in Sweden – finds that differences in heart rate and blood pressure in late adolescence may be associated with an increased lifetime risk for psychiatric disorders, including obsessive-compulsive disorder, schizophrenia, and anxiety disorders.
Previous smaller studies have reported elevated resting heart rate in people with major depressive disorder, post-traumatic stress disorder, generalized anxiety disorder, panic disorder, and psychotic disorders. Alterations in blood pressure have also been observed in people with schizophrenia, anxiety, and depression.
However, results of these studies have been inconsistent, with some studies reporting higher or lower blood pressure levels, and they have been skewed, in part, by side effects of medications.
The researchers aimed in this new large-scale cohort study to investigate whether differences in resting heart rate and blood pressure are associated with psychiatric disorders during the lifetimes of men in Sweden.
Researchers from Sweden and Finland conducted a study based on data of 1,794,361 Swedish men whose resting heart rate and blood pressure were measured at military conscription at an average age of 18 years between 1969-2010.
Antti Latvala, Ph.D., of the University of Helsinki in Finland, and co-authors included several potential factors that may influence the outcome of the results, including physical, cognitive, and socioeconomic factors. They included height, weight, and body mass index (BMI), due to their potential association with both cardiovascular functioning and the risk for mental disorders.
The data were adjusted for general cognitive ability (IQ), because, according to the study authors, IQ is associated with psychiatric morbidity, although its association with resting heart beat and blood pressure is unknown.
Similarly, compared with males in the lower heart rate category, men in the higher heart rate category had a 21 percent increased risk for schizophrenia and an 18 percent greater risk for anxiety. In contrast, teenage males with a lower resting heartbeat were linked to substance use disorders and violent convictions, particularly after adjusting for physical fitness.
The study authors reported similar associations for OCD, schizophrenia, anxiety, substance use disorders, and violence with higher and lower blood pressure readings.
“In this large-scale longitudinal cohort study, we found men with higher resting heart rate and higher blood pressure in late adolescence to be more likely to have received a diagnosis of OCD, schizophrenia, or anxiety disorder later in life,” say the authors.
The strongest associations were seen with OCD, with men in the higher resting heart rate category 70-80 percent more likely to be at risk than men in the lower category. Correspondingly, men in the highest blood pressure category had a 30-40 percent greater risk for OCD than men in the lowest blood pressure category.
“Our findings are novel; there are no previous prospective studies linking these cardiovascular measures to subsequent OCD, schizophrenia, or anxiety disorders,” the researchers note. However, they say that their findings cannot establish cause and effect.
The researchers point out that the data included were for men; therefore, it is uncertain whether the same results would be seen in women.
“Compared with men, women have a higher heart rate but show relatively greater parasympathetic control of the heart,” note the authors. “While these differences are poorly understood, they imply that associations between resting heart rate and psychiatric disorders may be different in men and women.”
Antti Latvala and colleagues summarize their findings:
“In a large and representative sample of men, higher resting heart rate and blood pressure in late adolescence were associated with subsequent diagnoses of OCD, schizophrenia, and anxiety disorders, whereas lower resting heart rate and blood pressure were associated with subsequent diagnoses of substance use disorders and violent criminality.”
These associations should be confirmed in other longitudinal studies, the authors write, and the underlying mechanisms should be investigated with more comprehensive measures to clarify causation, they conclude.