Table 2.
Measures of Apathy at 6 Weeks in 60 Patients With Alzheimer's Disease Randomly Assigned to Methylphenidate or Placebo
| Measure | Methylphenidate (n = 29) | Placebo (n = 31) | P Value |
|---|---|---|---|
| No. of patients with wk 6 data, n | 28 | 29 | |
| Apathy Evaluation Scale (AES) | |||
| Estimated score at 6 wk, mean (SE)a | 48.9 (2.1) | 52.0 (2.1) | |
| Estimated change from baseline to 6 wk, mean (SE)a | −1.9 (1.5) | 0.6 (1.4) | |
| Estimated treatment effect (methylphenidate – placebo), mean (95% CI)a | −2.5 (−6.5 to 1.6) | .23 | |
| ≥ 4-point improvement in AES from baseline to 6 wk, n (%) | 9 (32) | 8 (28) | .78 |
| ≥ 8-point improvement in AES from baseline to 6 wk, n (%) | 5 (18) | 3 (10) | .47 |
| ADCS-CGI-C change in apathy, n (%) | |||
| Marked improvement | 2 (7) | 0 (0) | |
| Moderate improvement | 4 (14) | 1 (3) | |
| Minimal improvement | 10 (36) | 7 (24) | |
| No change | 11 (39) | 20 (69) | |
| Minimal worsening | 1 (4) | 1 (3) | |
| Moderate worsening | 0 (0) | 0 (0) | |
| Marked worsening | 0 (0) | 0 (0) | |
| Estimated treatment effect (methylphenidate vs placebo), OR (95% CI)b | 3.7 (1.3 to 10.8) | .02 | |
| Neuropsychiatric Inventory apathy subscale | |||
| Estimated score at 6 wk, mean (SE)a | 2.9 (0.5) | 5.1 (0.5) | |
| Estimated change from baseline to 6 wk, mean (SE)a | −4.4 (0.6) | −2.6 (0.6) | |
| Estimated treatment effect (methylphenidate – placebo), mean (95% CI)a | −1.8(−3.4 to −0.3) | .02 | |
The score, change, and treatment effect are the model-based estimates (calculated using mixed model regression). The treatment effect is the comparison of within treatment group change from enrollment (the difference of differences) controlling for the stratification variable. A negative number favors methylphenidate. The number of people with ≥ 4- and ≥ 8-point improvement in AES score was compared using Fisher exact test.
The treatment effect is the odds ratio (calculated using proportional odds logistic regression) of being at or better than a given ADCS-CGI-C category for methylphenidate vs placebo controlling for the stratification variable. A number greater than 1 favors methylphenidate.
Abbreviations: ADCS-CGI-C = Alzheimer's Disease Cooperative Study-Clinical Global Impression of Change, CI = confidence interval, OR = odds ratio, SE = standard error.