Measures

Information on age, gender, and health condition (good/bad) was collected.

To evaluate olfactory function based on participants’ subjective senses, an olfactory visual analog scale (VAS), which takes into consideration the sensory impact of the test on participants, was used^{20, 21)}. The olfactory VAS uses a 10 cm (100 mm) scale bar, the left end of which indicates “I do not recognize it at all (0%)” and the right “I recognize it fully (100%)”. Participants were asked to mark a place on a line representing their degree of awareness of olfactory sensation, and the length (mm) from the left end of the line to the marked place was recorded as the VAS score (%). Takebayashi et al.²¹⁾ reported that this olfactory VAS has a correlation with the T&T olfactometer threshold test and that the cutoff value for olfactory disorders with a sensitivity of 95.5% and specificity of 88.0% is 47.0%.

In the present study, participants suspected of a clear olfactory disorder (olfactory VAS score of <47) were excluded from analysis.

The UPSIT is an olfaction test that is utilized worldwide. However, as the original version includes 11 scents not familiar to Japanese people, they were modified to create a Japanese version (UPSIT-J). This test is composed of 40 aromas (Table 1)¹⁹⁾. In this study, the questionnaire listed the Japanese names of the 40 scents on the UPSIT-J²²⁾ and the participants were asked, “Have you ever experienced recalling the past when you smelled this aroma in everyday life?” for each scent, determining the presence or absence of reminiscence experiences in everyday life when the participant smelled each one. Furthermore, in consideration of the burden on participants, instead of asking them to answer by actually smelling items, a questionnaire was distributed asking them to reflect on their daily lives.

^aItems names are not present in the UPSIT.