Characteristics and findings of included studies
| Number of patients | |
| COPD | 11 171 |
| Other forms of cognitive impairment diagnosed prior to inclusion | 46 |
| Controls | 48 689 |
| Age years mean | 67.53 |
| Cognitive impairment instruments used in more than one study | |
| Halstead-Reitan Test Battery | 3 |
| Wechsler Adult Intelligence Scale | 3 |
| Mental Deterioration Battery | 3 |
| Trail Making Test A-D | 7 |
| Wechsler Test of Adult Reading | 2 |
| Mini Mental State Examination | 14 |
| Wechsler Memory Scale-III test battery | 5 |
| Grooved pegboard test | 2 |
| Seashore Rhythm Test | 3 |
| Study design | |
| Cohort | 7 |
| Case–control | 14 |
| Observational | 2 |
| Cross-sectional | 2 |
| Interventional | 1 |
| Review articles (not included in table) | 5 |
| Studies reporting COPD and cognitive impairment | |
| An association between COPD and cognitive impairment | 20 |
| No association | 2 |
| Studies with statistically significant differences seen in COPD# | |
| Memory | 5 |
| Attention | 3 |
| Fluency | 4 |
| Language | 2 |
| Visuospatial | 3 |
COPD: chronic obstructive pulmonary disease. #: not all included studies reported domain-specific results.