Cognitive function in idiopathic pulmonary fibrosis

The purpose of this study was to investigate whether there is evidence that individuals with severe idiopathic pulmonary fibrosis (IPF) have cognitive deficits when compared to individuals with healthy lungs. Participants completed five neuropsychological tests: Trail Making Test (TMT) A and B, Stroop Color Word Test (1, 2, 3), Hopkins Verbal Learning Test, Boston Naming Test, and Grooved Pegboard Test, additionally, the short form-36 and Beck Depression Index. Twelve participants (7 male, mean age 69.3, 9.4 years) comprised the severe IPF group defined by a diffusion capacity for carbon monoxide (DLCO) <30%. Thirty-four patients (22 male, mean age 63.2, 9.6 years) comprised the mild-to-moderate group with a DLCO >30%. Participating spouses (n = 15, 4 male) served as the control group and had a mean age of 66.0, 10.8 years. Controlling for gender and age, the severe group had a significantly longer mean TMT B time (69.4, 135.9 seconds) than the mild group and the control group (86.7 seconds vs 83.2 seconds; p = 0.004 and 0.008 respectively), suggesting inferior performance on tasks requiring speed divided attention. In addition, the severe group had a significantly lower number of correctly identified colors in the Stroop 3 test (22.4 vs 30.6 vs 38.6; p < 0.001), suggesting slower processing speeds when requiring suppression of a familiar response. Participants with severe IPF had worse cognitive function than mild IPF or control subjects. Further research is needed to explain these findings and to develop interventions tailored to address these deficits.