4 | DISCUSSION
To our knowledge, our report is the first to show that lung cancer
itself without metastasis can cause cognitive impairment. Cancer of the
non-central nervous system has been shown to induce cognitive
impairment; however, its mechanism has not been well
studied.7 Moreover, little is known of the cognitive
function of patients with cancer prior to surgery, with only 3 studies
having evaluated the cognitive function of patients newly diagnosed with
breast cancer.7
The SAS and pathophysiological evidence in isolation cannot fully
explain the patient’s cognitive impairment. SAS can induce cognitive
impairment, especially the obstructive form of SAS, which has been
associated with general cognitive impairment.8 Our
current case presented general cognitive impairment one year after the
baseline visit, which gradually worsened despite the successful
introduction of CPAP. The patient did not show the typical cognitive
impairment of AD, although the pathophysiological findings using
PiB-PET, THK5351-PET, and IMP-SPECT indicated AD type impairment.
A limitation of our current report is that, although we observed the
patient longitudinally and in detail, we had only one case. Cohort
studies investigating non-central nervous system cancers, divided by
type, remain to be performed.