Table 2.
Studies reporting serum levels of β-carotene.
| Study | Location | Level of Evidence | Study Design | Participant Characteristics | Blood Levels | Condition | Outcome of Interest | Cognitive Test Used | Reference |
|---|---|---|---|---|---|---|---|---|---|
| Gerger et al. (2019) | Germany | 2 | Multi-centered randomized controlled trial | n = 56; female; aged 73.1 ± 5,8 y | BC (μM): 0.74 ± 0.65 | Subjects with mild cognitive impairment participating in the NeuroExercise study | Global cognition Verbal memory Working memory Attention Executive function |
MoCA ISLT ONB TMT |
[32] |
| Johnson et al. (2013) | USA(Georgia) | 4 | Cross-sectional | n = 298, of which 78 were octogenarians and 220 centenarians; male and female | BC (nmol/L): octogenarians, 568 ± 855; centenarians, 460 ± 432 |
Institutionalized and community-dwelling subjects compared; study conducted from 2001 to 2009 | Memory processing speed Attention Executive functioning |
MMSE GDRS SIB FOME WAIS-III Similarities subtest BDS COWAT |
[35] |
| Akbaraly et al. (2007) | France | 4 | Cross-sectional | n = 589; 361 female and 228 male; aged 73.5 ± 3 y | Trans-BC levels, 0.73 ± 0.52 μmol/L; cis-BC levels, 0.10 ± 0.12 μmol/L | Healthy old subjects | Global cognition Motor speed Working memory Executive function Attention and logical reasoning Verbal fluency |
MMSE TMTA TMTB DSST WFT |
[36] |
| Perkins et al. (1999) | USA | 4 | Cross-sectional | n = 4809; female; aged >60 y | BC normalized on units of total cholesterol: <0.06; 0.06–0.09; 0.09–0.15; >0.15 | Elderly, multi-ethnic group followed from 1988 to 1994 | Memory | Assessed using delayed recall (6 points from a story and 3 words), with poor memory defined by a combined score < 4 | [43] |
| Perrig et al. (1997) | Switzerland | 4 | Longitudinal and cross-sectional comparisons |
n = 442; 312 male, 132 female; aged 65 to 94 y |
BC measured in 1971 (T1) and 1993 (T2); BC levels (µg/dL): T1, 0.51 ± 0.31; T2, 0.72 ± 0.48 |
Healthy old subjects selected in T2 by random sampling from a large cohort established in T1; cognitive function assessed in T2 |
Implicit and explicit memory Working memory Semantic memory |
Free recall and recognitionWAIS-R Vocabulary test |
[28] |
T, time. Other abbreviations are presented in the Abbreviations section.