A limitation of this study is the relatively small size of
the participant population, which may partially account
for the weak association between some of the measurements
in our results. While the number of cases will be
continuously increased in our future study, we anticipate
that this study will lead to the realization of cognitive
impairment and some structural abnormalities of brain
in COPD patients in the field. Second, other brain regions,
especially the entorhinal cortex, transentorhinal and parahippocampal
gyrus which also play a critical role in the
neural control of cognitive function need to be examined.
Third, the MMSE, which has proven useful and sufficient
for cognitive measurements, provides a broad scale and
does not include measures of executive function. A
neuropsychological testing battery will have to be considered
in future studies to provide detailed analysis and
quantification of cognitive functions of patients. Nonetheless,
Table 4 Relationships between the relative test values
and MMSE score in the groups with COPD of different
severity
Test
parameter
Mild-to-moderate
COPD group MMSE
(n = 37)
Severe COPD
group MMSE
(n = 48)
Total COPD
group MMSE
(n = 85)
r P r P r P
PaO2 0.59