TABLE 3.
Mean cognitive scores by quintiles of selenium levels measured in nail samples, People’s Republic of China, December 2003–May 2005
| Quintiles of selenium level in nail samples (μg/g) |
||||||
|---|---|---|---|---|---|---|
| Quintile 1 (n = 393) | Quintile 2 (n = 406) | Quintile 3 (n = 390) | Quintile 4 (n = 406) | Quintile 5 (n = 405) | p value | |
| CSID* score (SD*) | 23.96 (3.47) | 24.96 (3.49) | 25.81 (3.44) | 25.83 (3.58) | 26.15 (3.35) | <0.001 |
| IU* Story Recall Test (SD) | 4.68 (2.32) | 4.86 (2.72) | 5.11 (2.87) | 5.67 (3.03) | 6.28 (3.12) | <0.001 |
| Animal Fluency Test (SD) | 12.67 (4.50) | 12.84 (4.99) | 12.50 (4.91) | 12.90 (5.24) | 12.77 (4.92) | 0.8063 |
| CERAD* Word List Learning Test (SD) | 12.59 (3.90) | 12.68 (3.90) | 12.98 (3.82) | 13.16 (3.96) | 13.81 (4.06) | <0.001 |
| CERAD Word List Recall Test (SD) | 4.49 (1.87) | 4.35 (1.84) | 4.71 (1.97) | 4.74 (1.92) | 4.88 (2.02) | <0.001 |
| IU Token Test (SD) | 14.32 (5.47) | 15.39 (5.35) | 16.22 (5.07) | 16.73 (5.25) | 17.35 (4.88) | <0.001 |
| Composite z score (SD) | −0.19 (0.72) | −0.10 (0.72) | 0.01 (0.72) | 0.08 (0.78) | 0.19 (0.77) | <0.001 |
*
CSID, Community Screening Instrument for Dementia; SD, standard deviation; IU, Indiana University; CERAD, Consortium to Establish a Registry for Alzheimer’s Disease.