OBESITY & HYPERTENSION – ‘TWO PEAS IN A POD’

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A.O. Akanji

Department of Medical Sciences, Frank H Netter, MD, School of Medicine, Quinnipiac University, USA.

Abstract

There is a global epidemic of obesity and hypertension. These two relatively common disorders derive from a basic underlying pathophysiologic abnormality, like ‘two peas in a pod’ There is a consensus that obesity predicts the future development of hypertension and that the relationship between blood pressure and body weight is linear independent of gender, age, and socioeconomic status. This brief commentary outlines the pathogenetic mechanisms for the obesity-hypertension association. These mechanisms are likely complex, multifactorial, and polygenic with possible roots in early ontogeny. A unifying hypothesis should integrate food intake and excess (resulting in weight gain) with increased sympathetic nervous activity (resulting in increased blood pressure). The adipokine, leptin,
appears well suited to fill that role – its hypothalamic signaling pathways and neurovascular outcomes are therefore explored in some detail. An understanding of these relationships from the perspectives of both epidemiology and pathophysiology is crucial to the management of both disorders – obesity with hypertension – and particularly more so in developing countries that lack the resources to deal with the looming epidemic of atherosclerotic cardiovascular disease.

Keywords: Obesity, Hypertension, Metabolic syndrome, Leptin, Sympathetic nervous system.

Introduction

The prevalence of obesity has ballooned over the past several years, independent of gender, race, ethnicity, or socio-economic stratification. In global terms, the prevalence of obesity and associated cardiovascular disease (CVD) has increased to the extent that >1 billion people are overweight or obese with staggering economic costs. It is currently estimated that obesity accounts for 2–7% of total global healthcare costs.^1.2. In the US, about 68% of adults are either overweight or obese, and rates in children and adolescents are rising, now close to 33%. These observations are mirrored by reports from not only other developed countries of Europe and Australasia but also in developing countries.^1,2

Concerning Africa, the World Health Organization (WHO; Africa Region) projected that 1 in 5 adults and one in 10 children and teenagers are likely to be obese by December 2023. The WHO further suggested that the prevalence of obesity among African adults and children/ adolescents will range from 14 -31% and 5 -17% respectively. In some support, a Lancet study from rural and urban Malawian subjects reported obesity rates of 9-44% in men and women, dependent on rural or urban domicile.³ The problem of overweight children is particularly concerning – in 2019, the continent was home to 24% of the world’s overweight children aged less than five years.

A systematic review and meta-analysis performed on a large number of subjects in Nigeria indicated that the respective prevalence rates of overweight and obesity were 26% and 15.0%, with an increasing trend, especially among urban dwellers.⁴ A study conducted in the Enugu metropolis (South-Eastern region of Nigeria) reported that obesity increased the odds of hypertension by as much as 50%.⁵

It is well recognized that increased body mass is an important CVD risk factor contributing to the current epidemic of atherosclerotic cardiovascular disease (ASCVD) particularly with its association with metabolic syndrome, hypertension, diabetes, dyslipidemia, and insulin resistance.

In an almost parallel fashion to obesity prevalence, there is also recognition of an increasing global prevalence of hypertension. In 2010, 31% of the world’s adults had hypertension with respective prevalence rates of 29% and 32% in high-income countries (HIC) and low to middle-income countries (LMIC).² This translates globally to about 1.4 billion people, distributed as 349 million in HIC and 1.04 billion in LMIC.²