Mild cognitive impairment was more likely in patients with chronic obstructive pulmonary disease (COPD), particularly the longer it went on, a study showed.
Physician-diagnosed COPD was associated with an 83% elevated likelihood of developing non-amnestic mild cognitive impairment, Michelle M. Mielke, PhD, of the Mayo Clinic in Rochester, Minn., and colleagues found.
That link was significant after full adjustment for other factors, including age, smoking and Alzheimer's genetics, although associations with the amnestic type of mild cognitive impairment -- thought to be a precursor to Alzheimer's disease -- were not, the researchers reported online in JAMA Neurology.
There was a dose-response relationship with mild cognitive impairment both of the non-amnestic type and overall.
Hazard ratios were highest among individuals with COPD diagnosed more than 5 years prior to the baseline assessment in the Mayo Clinic Study on Aging (1.58 overall, 95% CI 1.04-2.40, and 2.58 non-amnestic, 95% CI 1.32-5.06).
That prospective population-based cohort included 1,425 people, ages 70 to 89, at baseline who were cognitively normal when randomly selected from the county around the Mayo Clinic.
"Our findings highlight the importance of COPD as a risk factor for mild cognitive impairment and may provide a substrate for early intervention to prevent or delay the onset and progression of mild cognitive impairment," Mielke's group concluded.
Prior studies have linked COPD, particularly severe cases, to poor performance on attention, memory, and executive function tests.
Chronic lack of oxygen and excess carbon dioxide may damage the brain over time, and systemic inflammation and vascular problems also linked to COPD could play a role as well, Mielke and colleagues suggested.
Primary source: JAMA Neurology
Source reference: Singh B, et al "A prospective study of chronic obstructive pulmonary disease and the Risk for mild cognitive impairment" JAMA Neurol online, March 17, 2014.