Surprising links between hypertension and these 4 diseases
Key Takeaways
Hypertension increases the risk of heart attack and stroke, and represents a public-health scourge of gargantuan proportions. According to the CDC, more than 500,000 US deaths in 2019 had hypertension as a primary or secondary cause. Overall, 116 million American adults either have the condition or take antihypertensive medications. Alarmingly, only 24% of adults with hypertension have the disease under control.
Hypertension is inextricably linked to a gamut of other diseases, representing various organ systems. Here’s a look at four such relationships.
Ischemic stroke
One major repercussion of chronic hypertension involves cerebral arteries/arterioles, with increases in cerebrovascular resistance and brain hypoperfusion evident. Of note, pial vessels develop smaller lumens and increased tone in the long-term secondary to hypertension. Furthermore, hypertension increases the severity/extent of hypoperfusion and reduces the amount of penumbral tissue during ischemic stroke. (The penumbra is the hypoperfused tissue girding the ischemic core, to which blood flow is too low to sustain electric activity but high enough to maintain ion channels.)
According to the authors of a review published in the Journal of Cerebral Blood Flow & Metabolism, prolonged cerebrovascular resistance can lead to hypoperfusion and play a pivotal role in cerebral small vessel disease (CSVD), which in turn can lead to stroke. Hypertension also heightens pulse pressure and shear stress on the endothelium, resulting in disruption of the blood-brain barrier and vascular wall damage. These pathologic processes also contribute to CSVD.
Chronic hypertension interferes with cerebral circulation via structural remodeling, which entails hypertrophy and inward remodeling of cerebral arterioles. Higher levels of angiotensin II in hypertension mediates inward remodeling in cerebral arteries and arterioles, which helps explain the clinical utility of angiotensin-converting (ACE) inhibitors. Intriguingly, hypertension itself doesn’t trigger this remodeling.
Depression
Hypertension and depression combine in sinister ways and can increase the risk for all-cause mortality. In a study published in the Scandinavian Journal of Primary Care, investigators found that symptoms of depression are common in hypertensive patients without comorbidities who know they have hypertension. In other words, it appears that a person merely knowing that they have hypertension can play a role in depression.
“Many modifiable, lifestyle-associated factors may contribute to the association of hypertension and depressive symptoms,” the authors wrote. “Clinicians should consider depressive symptoms when treating hypertensive subjects and find ways to enhance their psychological well-being in order to promote a favourable lifestyle and control of hypertension.”
HIV
Hypertension is a burgeoning problem in those with HIV, with patients on antiretroviral therapy (ART) exhibiting a higher prevalence of the disease. According to global meta-analysis data cited by the authors of an article published in Hypertension, 35% of HIV-infected adults taking ART have hypertension compared with 30% of adults without HIV. Moreover, in adults aged 50 years or more, more than 50% have hypertension. The authors also cited data suggesting that among 80,000 US veterans, hypertension led to a twofold higher risk of incident acute myocardial infarction in those with HIV compared with those without it. HIV also increases the risk of other types of heart disease and all-cause mortality.
The authors wrote that novel pathophysiological mechanisms in individuals with HIV and hypertension include microbial translocation, chronic inflammation, immune suppression/reconstitution, viral tropism, lipodystrophy, adipokines, and HIV-related renal disease.
Obstructive sleep apnea
In the general population, the presence of obstructive sleep apnea (OSA) ranges between 4% and 7%, whereas hypertension affects between 30% and 40% of people. In those with OSA, about half also have hypertension, according to the Sleep Foundation.
In healthy people, blood pressure drops by between 10% and 20% at night, which is referred to as “blood pressure dipping.” People with severe OSA drop by less than 10% during sleep. This non-dipping pattern increases the risk of heart disease. Moreover, those with OSA have higher blood pressure when they wake up in the morning. This morning surge may also increase the chance of heart disease. OSA can also increase daytime blood pressure levels, depending on severity.
OSA leads to overactivation of the sympathetic nervous system, which in turn may lead to hypertension. Every time airways collapse in a person with OSA, breathing ceases, which leads to sympathetic activation and blood pressure spikes. When a person with OSA is roused from sleep after an OSA event, sympathetic tone and blood pressure spike to an even greater magnitude.
The sleep disruption of OSA prompts the adrenal glands to release catecholamines, including epinephrine and dopamine, which activate the sympathetic system and elevate blood pressure.
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