A double-blinded, placebo-controlled, randomized trial of the neuropsychologic efficacy of cranberry juice in a sample of cognitively intact older adults: pilot study findings

Abstract

Objectives: The aim of this research was to conduct the first known clinical trial of the short-term (i.e., 6 weeks) efficacy of cranberry juice on the neuropsychologic functioning of cognitively intact older adults.

Participants: Fifty (50) community-dwelling, cognitively intact volunteers, > or = 60 years old, who reported no history of dementia or significant neurocognitive impairments, participated in this study.

Design: A 6-week, double-blind, placebo-controlled, randomized, parallel-group, clinical trial was utilized. Participants were randomly assigned to receive either 32 ounces/day of a beverage containing 27% cranberry juice per volume (n = 25) or placebo (n = 25) for 6 weeks, and administered a series of neuropsychologic tests at both pretreatment baseline and again after 6 weeks of either cranberry juice or placebo treatment to assess treatment-related changes.

Outcome measures: Efficacy measures consisted of participants' raw scores on the following standardized neuropsychologic tests: Selective Reminding Test, Wechsler Memory Scale-III Faces I and Faces II subtests, Trail Making Test (Parts A and B), Stroop Color and Word Test, and the Wechsler Adult Intelligence Scale- III Digit Symbol-Coding subtest. A subjective Follow-up Self-report Questionnaire was also administered to participants at the conclusion of the end-of-treatment phase assessments.

Results: Two-factor, mixed analyses of variance (ANOVA) revealed no significant group (cranberry juice and placebo) by trial (pretreatment baseline and end-of-treatment assessments) interactions across all of the neuropsychologic tests and measures utilized in this study when a Bonferroni corrected alpha level was used to correct for multiple comparisons (i.e., .05/17 group by trial comparisons = .003). Pearson Chi-Square analyses of the groups' self-reported changes over the 6-week treatment phase in their abilities to remember, thinking processes, moods, energy levels, and overall health on the Follow-up Self-report Questionnaire revealed no significant relationships. However, a nonsignificant trend (X2(1) = 2.373, p = 0.123) was noted for participants' self-reported overall abilities to remember from pretreatment baseline to the end-of-treatment assessment. Specifically, more than twice as many participants in the cranberry group (n = 9, 37.5%) rated their overall abilities to remember by treatment end as "improved" as compared to placebo controls (n = 4, 17.4%).

Conclusions: Taken together, no significant interactions were found between the cranberry and placebo groups and their pretreatment baseline and end-of-treatment phase (after 6 weeks) standardized neuropsychologic assessments. A nonsignificant trend was noted, however, on a subjective, self-report questionnaire where twice as many participants in the cranberry group rated their overall abilities to remember by treatment end as "improved" compared to placebo controls.