Cognitive deficits seen in PAH may be due to blood vessel remodeling

Small study finds mild impairments, suggests link to changes in vessels in brain

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by Andrea Lobo |

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About one-quarter of the pulmonary arterial hypertension (PAH) patients in a small study showed cognitive deficits, typically mild impairments in executive function and memory.

Problems in abilities like executive function — a set of skills that include thinking, self control, and readily accessible memory that’s part of everyday life — might be related to changes in cerebral blood vessels.

Structural changes (remodeling) in blood vessels of the lungs possibly drive the cognitive problems identified in these patients, the investigators suggested.

“Further investigation is needed to determine the relationship between cognitive impairment and pulmonary vascular and cerebrovascular remodeling in PAH,” they wrote.

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Cognitive deficits were reported in previous studies in PAH patients

The study, “Cognitive impairment in pulmonary arterial hypertension,” was published in the journal Annals of Clinical and Translational Neurology.

PAH is caused by the narrowing of pulmonary arteries, which carry blood from the heart through the lungs, raising blood pressure in those arteries and weakening the heart’s right ventricle.

Previous studies indicate that the disease can affect other organs, and some studies suggest cognitive problems could be fairly common in people with PAH.

However, “both the underlying mechanism and the relationship between cardiopulmonary and cognitive dysfunction in PAH are unknown,” the researchers wrote.

Scientists with Yale University School of Medicine examined 23 adults diagnosed with PAH between February 2020 and December 2021 at their clinic.

Patients’ mean age was 63, a majority were women (52%), and most (91%) identified as white. None were diagnosed with any condition related to cognitive difficulties.

6 of 23 patients showed problems in executive function on a cognition test

Cognitive function was determined using the Self-Administered Gerocognitive Exam (SAGE) score, a screening tool that measures cognition in several domains, and is used to identify mild cognitive impairment and early dementia. A score below 17 indicates a deficit.

Six people (26%) met the criteria for cognitive impairment, most commonly mild, corresponding to a SAGE score of 15 or 16. All had problems related to executive function, and most had difficulties in memory, calculation, and visual and spatial tasks.

These findings are consistent with a cognitive impairment syndrome associated with remodeling in pulmonary blood vessels, suggesting similar blood vessels changes in certain regions of the brain, the researchers noted.

“Further investigation is needed to determine the relationship between cognitive impairment and pulmonary vascular and cerebrovascular remodeling in PAH,” they wrote. “Decreased cerebral blood flow resulting from diminished cardiac output could play a role in this process as well.”

Cognitive evaluation was performed on the same day as cardiopulmonary exercise testing, used to determine pulmonary hypertension stage and severity. In this study, it consisted of going up and down a step for three minutes, combined with lung function assessment.

The parameter most closely associated with cognitive impairment was a lower gas exchange-derived pulmonary vascular capacitance (GXCAP), a measure previously shown to correlate with pulmonary artery ability to expand and contract.

Systemic oxygen desaturation after exercise, meaning insufficient blood oxygen, also correlated with the patients’ cognitive deficits.

“The decrease in GXCAP and systemic [oxygen] desaturation observed in the current study most likely represent increased … pulmonary vascular burden and vascular remodeling seen in PAH,” the researchers wrote.

Study limitations included its small size, small number of patients of various racial groups, and limited cognitive testing measures.

“Directions for future studies include larger studies with more in-depth cognitive testing … and investigations of the relationship between pulmonary vascular remodeling, cerebrovascular disease, and cognitive impairment in PAH,” the scientists concluded.

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