Table 2:
The associations of GDS score at baseline with baseline cognitive function and with cognitive decline
| model 1 | ||||||
|---|---|---|---|---|---|---|
| cognitive domain | effect | estimate | SE | DF | t value | p |
| Overall cognitive score | *GDS bl | −0.1175 | 0.02102 | 1014 | −5.59 | <.0001 |
| GDS bl · t yr | −0.00060 | 0.000348 | 1495 | −1.72 | 0.0854 | |
| Executive functions | GDS bl | −0.1863 | 0.03617 | 1013 | −5.15 | <.0001 |
| GDS bl · t yr | −0.00086 | 0.000676 | 729 | −1.28 | 0.2019 | |
| Working memory/ attention | GDS bl | −0.04562 | 0.02709 | 1028 | −1.68 | 0.0924 |
| GDS bl · t yr | −0.0005 | 0.000564 | 1495 | −0.89 | 0.3736 | |
| Semantic categorization | GDS bl | −0.1551 | 0.02927 | 1008 | −5.3 | <.0001 |
| GDS bl · t yr | −0.0001 | 0.000448 | 1479 | −0.23 | 0.8175 | |
| Episodic memory | GDS bl | −0.08165 | 0.02795 | 1035 | −2.92 | 0.0036 |
| GDS bl · t yr | −0.00141 | 0.000708 | 719 | −2 | 0.0462 | |
| model 2 | ||||||
| cognitive domain | effect | estimate | SE | DF | t value | p |
| Overall cognitive score | GDS bl | −0.1170 | 0.02142 | 971 | −5.46 | <.0001 |
| GDS bl · t yr | −0.00053 | 0.000358 | 693 | −1.48 | 0.1387 | |
| Executive functions | GDS bl | −0.1781 | 0.03647 | 971 | −4.88 | <.0001 |
| GDS bl · t yr | −0.00084 | 0.00069 | 714 | −1.21 | 0.2257 | |
| Working memory/ attention | GDS bl | −0.05381 | 0.0279 | 984 | −1.93 | 0.0541 |
| GDS bl · t yr | −0.00021 | 0.000573 | 1441 | −0.37 | 0.7146 | |
| Semantic categorization | GDS bl | −0.1512 | 0.02972 | 968 | −5.09 | <.0001 |
| GDS bl · t yr | −0.00008 | 0.000456 | 1429 | −0.18 | 0.8582 | |
| Episodic memory | GDS bl | −0.08547 | 0.02866 | 992 | −2.98 | 0.0029 |
| GDS bl · t yr | −0.00127 | 0.00073 | 701 | −1.74 | 0.829 | |
GDS bl is the GDS score at baseline and t is the follow-up time in year. GDS bl · t yr is the interaction term. A non-significant GDS bl · t yr interaction suggests that the effect of baseline GDS on cognition is constant over time. Because the coefficient for GDS bl is negative, a significant positive interaction indicates that the effect of baseline GDS on cognition diminishes over time, whereas a significant negative interaction indicates that the effect worsens over time. Controlling for other covariates and assuming no change in GDS during follow-up, every χ increase in baseline GDS is associated with B GDSbl · (χ) + B GDSbl · t yr · (χ t) change in cognitive z score. For example, for episodic memory domain, if subject A had a baseline GDS score 2 points higher than subject B, then the z score for subject A would be 0.082 ·2 + 0.001 · 2 ·1 = 0.162 (Model 1) lower than subject B at follow-up Year 1, and 0.082·2 + 0.001 · 2 ·3 = 0.170 at year 3.
Model 1: controlling for age, sex, education
Model 2: controlling for age, sex, education, diabetes duration, cholesterol, creatinine, HbA1c, triglycerides, systolic and diastolic blood pressure, BMI at baseline.