Table 5.

Comparison of the changes of neurocognitive function according to the type of shift work.

Domain	Type of Shift Work	Model 1		Model 2		Model 3
		LSmeans	p-Value	LSmeans	p-Value	LSmeans	p-Value
Composite memory	3-day cycle	8.38	0.503	9.26	0.493	8.68	0.483
	6-day cycle	4.74		5.06		4.59
	9-day cycle	3.81		4.82		4.18
	21-day cycle	6.50		7.35		7.07
Verbal memory	3-day cycle	−20.17	0.030	−15.78	0.060	−15.92	0.071
	6-day cycle	−15.49 9		−12.13		−12.07
	9-day cycle	−25.95 6,21		−13.01		−21.21
	21-day cycle	−17.19 9		−15.78		−12.68
Visual memory	3-day cycle	6.20	0.327	6.39	0.246	5.34	0.313
	6-day cycle	1.30		0.61		0.12
	9-day cycle	1.49		1.30		0.69
	21-day cycle	3.79		3.59		3.29
Complex attention	3-day cycle	0.21	0.563	0.29	0.499	−0.15	0.547
	6-day cycle	7.03		7.75		6.86
	9-day cycle	4.11		4.53		4.29
	21-day cycle	5.63		6.50		6.32
Psychomotor speed †	3-day cycle	2.04	0.307	2.40	0.215	1.81	0.279
	6-day cycle	0.31		0.10		−0.41
	9-day cycle	3.66		3.96		3.15
	21-day cycle	2.71		2.68		2.15
Motor speed ‡	3-day cycle	4.21	0.131	3.25	0.075	3.20	0.112
	6-day cycle	3.14		1.92		1.69
	9-day cycle	4.31		3.29		2.81
	21-day cycle	1.00		−0.39		−0.50
Processing speed ††	3-day cycle	−2.66 21	<0.001	−0.23 21	<0.001	−1.47 21	<0.001
	6-day cycle	−4.21 9,21		−2.37 9,21		−2.93 9,21
	9-day cycle	1.12 6		3.60 6		2.64 6
	21-day cycle	3.88 3,6		6.36 3,6		5.50 3,6
Reaction time	3-day cycle	−0.69	0.986	1.64	0.907	2.52	0.860
	6-day cycle	−0.56		0.71		1.47
	9-day cycle	0.04		2.41		3.50
	21-day cycle	−0.09		1.57		2.41
Cognitive flexibility	3-day cycle	−3.24 21	<0.001	−3.02 21	<0.001	−2.88 21	<0.001
	6-day cycle	−3.74 21		−4.53 21		−4.62 21
	9-day cycle	0.20 21		−0.36 21		−0.05 21
	21-day cycle	5.25 3,6,9		4.90 3,6,9		5.18 3,6,9
Executive functioning	3-day cycle	−3.52 21	<0.001	−3.21 21	<0.001	−3.10 21	<0.001
	6-day cycle	−4.78 21		−5.51 21		−5.39 21
	9-day cycle	−0.46 21		−0.83 21		−0.59 21
	21-day cycle	4.77 3,6,9		4.42 3,6,9		4.80 3,6,9
Neurocognitive index	3-day cycle	1.46	0.291	2.19	0.269	1.52	0.225
	6-day cycle	1.57		1.77		2.92
	9-day cycle	2.35		3.00		4.55
	21-day cycle	3.99		4.53		2.07

Analyzed by general linear model. Types of shift work with significant differences in multiple comparisons are listed with a superscript (³: 3-day cycle, ⁶: 6-day cycle, ⁹: 9-day cycle, ²¹: 21-day cycle). Model 1: unadjusted. Model 2: adjustment for age, sex, and education level. Model 3: Model 2 + adjustments for income, job, and ISI/PHQ-9 scores. LSmeans: least square means. ^† PHQ-9 score (β: 1.05, 95% confidence interval (CI) 0.54 to 1.56) was significantly associated with change in the domain of psychomotor speed. ^‡ Age was significantly associated with change in the domain of reaction time in Model 2 (β: −0.30, 95% CI −0.48 to −0.12) and Model 3 (β: −0.26, 95% CI −0.48 to −0.03). ^†† ISI (β: −0.58, 95% CI −0.94 to −0.21) and PHQ-9 (β: 1.32, 95% CI 0.67 to −1.98) scores were significantly associated with change in the domain of processing speed.