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Lung disease tied to greater risk for dementia, mild cognitive impairment

Both restrictive and obstructive lung disease were associated with greater risk for incident dementia and mild cognitive impairment in middle-aged adults, according to findings recently published in the American Journal of Respiratory and Critical Care Medicine.

“Prior studies have suggested that poor lung health may be linked to great risk of dementia or worsening cognitive ability. Though these studies have provided valuable information, they often had relatively short follow-up or did not have careful ascertainment of dementia. Dementia has a very long natural history, meaning that it takes a long time for the disease to develop,” Pamela L. Lutsey, MD, PhD, of the division of epidemiology and community health at the University of Minnesota, told Healio Family Medicine.

Lutsey and colleagues analyzed data from 14,184 participants (mean age, 54.2 years) of the Atherosclerosis Risk in Communities cohort that underwent spirometry and were asked about lung health. During a median of 23 years follow-up, participants’ dementia and mild cognitive impairment were ascertained by hospital records and/or comprehensive neurocognitive exams.

Researchers found compared with those without respiratory symptoms or disease, the odds for dementia or mild cognitive impairment were higher among participants with restrictive (multivariable-adjusted OR = 1.58; 95% CI, 1.15-2.19) and obstructive lung disease (multivariable-aOR = 1.29; 95% CI, 1.05-1.59). These associations were similar in analyses limited to nonsmokers and occurred in both Alzheimer’s disease-related dementia and cerebrovascular etiologies. In addition, forced vital capacity and low FEV₁ were also tied to increased risk for dementia.

“I had actually expected to see the strongest associations with obstructive lung disease,” Lutsey said in the interview.

“However, the stronger association with restrictive impairment is not entirely surprising. Diseases which result in restrictive impairment, such as idiopathic pulmonary fibrosis and sarcoidosis, are characterized by reduced lung volumes and low oxygen levels. Extensive work in experimental rodent models of sleep apnea have suggested that intermittent low oxygen levels may damage neurons. Our study is novel in that relatively little research has evaluated the impact of a constant state of hypoxemia, which may be common in the context of restrictive impairment, on neurologic structure and function,” she continued.

Lutsey added the findings, if shown to be causal, might have an impact that goes beyond a clinician’s office.

“If confirmed that lung disease is also linked to dementia, both individuals and policy makers would have added incentive to make changes that protect lung health, as doing so may also prevent dementia. – by Janel Miller

Disclosures: Healio Family Medicine was unable to determine the authors’ relevant financial disclosures prior to publication.