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. 2017 May 10;46(6):988–993. doi: 10.1093/ageing/afx077

Subjective cognitive concerns are associated with objective memory performance in Caucasian but not African-American persons

Jonathan D Jackson 1,2,1, Dorene M Rentz 1,2,3, Sarah L Aghjayan 3, Rachel F Buckley 1,2,4, Tamy-Fee Meneide 1, Reisa A Sperling 1,2,3, Rebecca E Amariglio 1,2,3
PMCID: PMC5860175  PMID: 29088363

Abstract

Objective

subjective cognitive concerns (SCC) have been proposed as a means of identifying individuals at risk for Alzheimer's disease (AD). However, the utility of SCCs has not been well-explored for African-Americans, who are twice as likely to develop AD dementia as Caucasians. We investigated whether race affects the association between SCCs and objective memory performance.

Methods

we used a composite of three SCC questionnaires, and three challenging episodic memory tests. We studied 289 (61% female; African-American n = 47) clinically normal older individuals. Two hierarchical linear regressions assessed the modifying role of race on the association between SCC and objective memory performance. The first regression was conducted on the full sample, while the second matched the racial groups on age, estimated verbal IQ and socioeconomic status.

Results

in the full sample, both groups reported similar levels of SCCs, P = 0.10, although African-Americans performed worse on the memory tasks, P < 0.001. No group differences were observed in the matched sample. The SCC × race interaction term was nonsignificant in the full sample, β = 0.109, P = 0.09, but was significant in the matched sample, β = 0.422, P = 0.037. While a significant correlation was observed between SCCs and memory among Caucasians, r = −0.401, the correlation was not found among African-Americans, r = −0.052.

Conclusions

results suggest that the dissociation between SCCs and memory performance in African-Americans may indicate qualitative differences in how diverse groups endorse cognitive concerns, even after considering socioeconomic and educational factors.

Keywords: memory, subjective cognitive concern, race, African-American, older adult

Introduction

Mounting evidence suggests that subjective cognitive concerns (SCCs) are an early indicator of decline consistent with Alzheimer's disease (AD) [1–9], and are correlated with objective memory performance [10]. SCCs may therefore complement objective memory measures, particularly prior to clinical impairment. Yet the utility of SCCs has not been well explored in groups that may differ in dementia risk. For example, African-Americans are thought to be twice as likely as Caucasians to develop dementia [11–14] (dementia rates are noted to be lower in some African cohorts [12]), suggesting dementia risk is influenced by physical or cultural environment or perhaps a genetic–environment interaction. Moreover, African-Americans tend to perform worse than Caucasians on cognitive measures in older adulthood [15–21], which has been attributed to lifestyle factors such as socioeconomic status (SES), early-life education and literacy [21–29].

Research on racial differences in SCCs has not been widely studied. To our knowledge, only two studies have examined SCCs in older African-Americans with respect to cognition. One study found that Caucasians were more likely to report SCCs but tended to outperform African-Americans on a cognitive screening test [16]. In contrast, African-Americans had greater cognitive decline over 3 years relative to Caucasians while controlling for depression, baseline cognitive performance and education. Another study found no relationship between subjective complaints and objective memory performance [30]. Though both studies had large sample sizes, they did not directly compare racial differences on robust measures of SCCs.

The focus of this preliminary study was to investigate differences in SCCs as a function of race, and whether these differences were associated with subjective concerns and objective measures of cognition using detailed and challenging measures. Furthermore, using an a priori, matched-pairs analysis, we sought to clarify whether measures commonly cited in differentiating health outcomes for African-Americans and Caucasians, namely SES and estimated verbal IQ [13, 21, 23, 24, 27–29], could likewise account for observed differences in the endorsement of SCCs and their association with objective memory performance. In this way, the matched-pair analysis complements and extends the full sample analysis, determining whether SCC interacts with race in associating with memory performance once verbal IQ and SES are controlled. Given that African-Americans and Caucasians cohorts in many studies differ on memory performance, education, reading ability and SES, variables relevant for cognitive assessment [12, 13, 15, 16, 22–24, 26, 31], the matched-pairs analysis is an appropriate tool, facilitating clear comparisons between groups when these variables are held constant.

Methods

A total of 289 participants (age: 73.7 ± 6.2, years of education: 15.7 ± 3.1, 60.6% women, 16.3% African-American) were studied using protocols and informed consent procedures approved by the Partners Healthcare Human Research Committee. Inclusion and exclusion criteria are further detailed in the Supplementary data, Appendix, available at Age and Ageing online.

SCCs composite

Participants completed three SCC questionnaires including: (i) the self-rated version of the Everyday Cognition scale (E-Cog [32]), (ii) the Memory Functioning Questionnaire (MFQ [33, 34]) and (iii) a set of 7 yes-or-no questions that have been used previously in large epidemiological studies to assess cognitive changes in older individuals [1, 35]. As in Ref. [36], we combined these scales to create an SCC composite score, which is detailed in the Supplementary data, Appendix, available at Age and Ageing online. Higher composite scores indicate more subjective concerns. All SCC questionnaires were completed prior to cognitive testing.

Memory performance factor

A description of the derivation of the memory factor score was reported in Ref. [37]. Briefly, the factor was comprised of weighted scores from three challenging memory tests: The Face-Name Associative Memory Exam task [36, 38], delayed recall from the Six-Trial Selective Reminding Test [39] and free recall performance from the Memory Capacity Test [40, 41]. Higher scores indicate better memory performance.

Analytic approach

We performed a pair of hierarchical linear regression analyses to address our primary question regarding the effects of race, SCCs, and the interaction of these variables on objective memory performance. The first regression was comprised of the full sample (n = 289), while the second matched a subset of Caucasian participants to the African-American participants on age, estimated verbal IQ and SES (n = 94). Matching was conducted using the FUZZY algorithm in SPSS version 22.0. All continuous variables were standardised, and the standardised variables were multiplied to create interaction terms. Because of known effects on cognitive outcomes related to race [13, 21, 23, 24, 27–29], covariates included sex, symptoms of depression (GDS score), APOE4 status, age, estimated verbal IQ (American National Adult Reading Test [42]), SES based on educational and vocational attainment (Hollingshead Two-Factor Index [43]), where higher scores refer to lower social privilege. We preferred verbal IQ over years of education as a covariate because it is more sensitive to variation in educational quality, which is known to affect racial differences in cognitive performance [26], perhaps due to socioeconomic differences between the groups. In the matched sample, sex, symptoms of depression and APOE comprised the covariates. In each regression model, covariates were entered first, followed by SCC, race and the SCC × race interaction in the second step. An alpha of 0.05 was set to indicate significance. Between-groups comparisons were conducted after using's Levene's test for equality of variances. Where necessary, unequal-variance t tests were used in place of Student's t test to compensate for heteroscedasticity.

Results

Demographic information as a function of race is reported in Table 1. Relative to Caucasians (n = 242), African-Americans (n = 47) reported fewer years of education (t(287) = 4.27, P < 0.001), lower MMSE scores (t(54.4) = 3.24, P = 0.002), lower verbal IQ (t(54.0) = 6.43, P < 0.001), and worse socioeconomic standing (t(287) = 4.13, P < 0.001). African-Americans also performed worse on the memory factor (t(287) = 4.84, P < 0.001), but reported no more SCCs than Caucasians (t(56.76) = 1.69, P = 0.10). There were no group differences with respect to age or depression (ts < 1), or of apolipoprotein E4 status (χ2(1) = 0.527, P = 0.468).

Table 1.

Mean (SDs) demographic information as a function of race.

Measure Caucasian Caucasian (matched sample) African-American
N (female) 242 (139) 47 (26) 47 (36)
Age 73.8 (6.2) 74.6 (6.8) 73.3 (6.4)
Education* 16.1 (3.1) 13.8 (3.2) 14.0 (2.9)
Mini-Mental State Exam* 29.1 (1.0) 28.7 (1.1) 28.4 (1.4)
American National Adult Reading Test* 122.6 (7.8) 110.0 (6.6) 111.0 (11.9)
Hollingshead index* 26.3 (14.7) 33.9 (14.6) 36.1 (15.9)
Geriatric depression scale 2.4 (2.4) 1.8 (2.0) 2.5 (3.2)
Memory factor score* 5.7 (2.1) 4.4 (1.8) 4.1 (2.0)
Subjective cognitive concerns composite 0.0 (0.7) 0.0 (0.7) 0.2 (1.0)
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*P < 0.05 between full Caucasian sample and African-Americans, Mann–Whitney U.

In the matched sample, relative to Caucasians (n = 47), African-Americans (n = 47) demonstrated no differences in age (t < 1), years of education (t < 1), MMSE (t(92) = 1.12, P = 0.27), verbal IQ (t < 1), socioeconomic standing (t < 1), depression (t(73.4) = 1.27, P = 0.21), memory (t < 1), or SCCs (t(92) = 1.49, P = 0.14), or of apolipoprotein E4 status (χ2(1) = 0.532, P = 0.466). Because the sample size was relatively limited, we also conducted Wilcoxon signed-rank tests on the variables and covariates in the matched sample to determine whether distributional differences emerged as a function of race. No distributional differences emerged as a function of age (Z = 1.106, P = 0.269), verbal IQ (Z = 0.776, P = 0.437), GDS (Z = 1.185, P = 0.236), SES (Z = 1.004, P = 0.315), memory performance (Z = 0.751, P = 0.452) or SCC (Z = 1.249, P = 0.212).

Full sample analysis

Table 2 summarizes the hierarchical linear regression analyses in both the full and matched samples. Covariates accounted for a significant amount of variance to the memory factor score, R2 = 0.25, F(6, 256) = 13.93, P < 0.001. The second step of the regression was also significant, ∆R2 = 0.05, F(3, 253) = 6.45, P < 0.001. The main effects of race (β = −0.177, P = 0.004) and SCC (β = −0.223, P = 0.001) both contributed significant variance to memory performance, while there was a nonsignificant trend for the interaction term (β = 0.109, P = 0.09).

Table 2.

Results from hierarchical linear regression models predicting memory performance in full and matched samples.

Order of entry into model β ∆R2 P
Full sample
 Step 1: Covariates 0.246 <0.001
 Step 2: Variables of interest 0.054 <0.001
  SCC −0.223 0.001
  Race −0.177 0.004
  SCC × race 0.109 0.090
Matched sample
 Step 1: Covariates 0.016 0.742
 Step 2: Variables of interest 0.118 0.023
  SCC −0.558 0.006
  Race −0.163 0.157
  SCC × race 0.422 0.037
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Matched sample analysis—age, SES and verbal IQ

Covariates did not contribute significant variance to the memory factor score, R2 = 0.02, F < 1. The second step of the regression was significant, however, ∆R2 = 0.12, F(3, 74) = 3.36, P = 0.023. SCC (β = −0.558, P < 0.001) but not race (β = −0.163, P = 0.16) contributed significant variance to memory performance. These were subsumed under a significant SCC × race interaction term (β = 0.422, P = 0.037). Follow-up partial correlations controlling for sex, depression and APOE revealed a significant negative association between SCC and memory performance for Caucasians (r = −0.401) but not African-Americans (r = −0.052). The associations between SCCs and objective memory performance as a function of race are summarised in Figure 1. Correlations among the individual SCC and memory measures, as a function of race, are summarised in Figure 2.

Figure 1.

Figure 1.

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Scatterplot depicting racial differences in the relationship between subjective cognitive concerns and memory performance. Measures are residualized for sex, depression scores, and APOE genetic status.

Figure 2.

Figure 2.

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Correlation matrix among the individual subjective cognitive concerns and episodic memory measures, displayed as a function of race.

Discussion

We found that although African-Americans performed worse on objective memory measures compared to Caucasians, the groups did not differ in SCC reports. In the full sample, which contained a larger cohort of Caucasians, we observed the expected main effects of SCC, where more complaints were associated with worse memory performance, as well as of race, where African-Americans performed worse relative to Caucasians. This demonstrates concordance with the broader extant literature on SCCs [1, 36, 44] and race [16, 17, 21, 29]. We also observed a nonsignificant trend toward an interaction between race and SCC.

More interestingly, when matching groups on variables that typically account for differences between Caucasians and African-Americans, namely SES and verbal IQ, in addition to age, racial differences on memory performance were attenuated. This too is in line with previous research demonstrating that SES and estimated verbal IQ may underpin racial disparities in cognitive measures [13, 21, 23, 24, 27–29]. The matched sample yielded a significant interaction between SCCs and race, where SCCs and objective memory were correlated in Caucasians, but not in African-Americans. This novel finding suggests there are differential associations between SCCs and objective memory performance as a function of race, and that these may be readily observed when ensuring groups are equal on key demographic variables.

Our use of an SCC composite and objective memory composites derived from several challenging tests in a diverse sample may extend and help clarify results from previous reports. Conceptually, this key finding replicates results reported by Sims et al. [30], who likewise made use of extensive SCC and memory measures, but did not observe a link between them in African-Americans, as well as [45], who found that while MMSE performance was associated with subjective reports of memory and behaviour problems in Caucasians, the relationship did not extend to African-Americans. The current findings diverge somewhat from Ref. [16], who found that African-Americans were less likely to endorse cognitive concerns than Caucasians. It may be possible that group differences emerged from the use of composite measures, rather than individual assessment tools. We conducted correlations among the three measures used in the SCC composite in the matched sample and found that the correlations in the Caucasian group (r range: 0.313–0.541) were similar to those in the African-American group (r range: 0.451–0.665). Likewise, the correlations in the memory factor score were comparable between the Caucasian (r range: 0.312–0.421) and African-American groups (r range: 0.459–0.553). Even though the composites of SCC and objective memory do not appear to relate to one another in the African-American group, it appears that these composites are internally stable between races.

As for why a relationship between SCCs and objective memory was observed in Caucasians and not African-Americans in our sample, a clear explanation remains elusive. We speculatively hypothesise that cultural and lifestyle factors are likely to account for differences rather than race as an inherent trait construct, such that SCCs that are salient to one cultural group may not be salient to another. Although there were no differences in overall reports of SCCs between Caucasians and African-Americans, historically these subjective report measures have been developed and validated on largely Caucasian populations. Given that African-Americans and Caucasians did not differ on either subjective or objective measures of cognition in the matched sample, the dissociation between SCC and the memory factor in African-Americans may suggest qualitative, cultural differences in how each racial group endorses cognitive concerns, which in turn lead to different relationships with objective memory measures. For example, Caucasians’ cultural influences may simply make them more likely to endorse SCCs that preferentially associate with memory performance. It is also possible that factors such as educational attainment may have a more complex effect on SCCs beyond the negative association that has sometimes been reported [46–48]. In line with this possibility, there is recent evidence that suggests SCCs may be differentially modulated by educational attainment. Recently [49] reported that some SCCs such as use of notes increases with educational attainment while others, such as transient confusion, tend to decease with higher education.

Additionally, it is possible that racial differences in other aspects of health may play a role in differences in the association between SCCs and memory performance. Using the matched sample, we compared African-Americans and Caucasians on measures of blood pressure (systolic and diastolic), cholesterol (HDL and LDL), glucose and body-mass index (BMI). No differences emerged for measures of glucose, cholesterol, or blood pressure (all ts < 1.3), although there was a nonsignificant trends toward African-Americans having higher BMI (Caucasian M = 28.0, African-American M = 29.8, t(88) = 1.8, P = 0.074, with four missing datapoints from the African-American sample). Taken together, cultural, health, environmental differences across racial groups may yet emerge with respect to which SCCs are considered a normal part of the aging profile rather than endorsed as abnormal and a cause for worry.

Given that the current study investigated a SCC composite, rather than comparing SCCs at an item level, in the future it will be important to determine differential patterns of SCC endorsement across racial and cultural groups. Although consensus statements on the clinical utility of SCCs are emerging [50], there has not been a significant amount of research on which kinds of individual SCCs are likely to predict memory performance in cognitive or clinical settings, much less with respect to race (although see [51–53]). Additionally, the current study represents a preliminary cross-sectional approach to SCCs and cognition; more detailed investigations are needed to understand how SCCs relate to cognitive change over time among racially diverse groups [16] as well as how SCCs are associated with other aspects of clinically relevant biomarkers, such as amyloid or tau deposition in the brain, white matter hyperintensities, or progression to clinically defined AD dementia. Another study limitation is that although our study cohort is representative with regard to African-Americans, it is important to replicate these data in a sample with more African-Americans. Confirming these effects with a larger, more diverse dataset will help clarify how and whether SCCs truly differ as a function of racial identity.

In summary, the current study explored the effect of race on SCCs and their association with objective memory performance. While groups did not differ on frequency of SCCs, when matched on SES and estimated verbal IQ, Caucasians demonstrated a significant association between SCCs and objective memory performance that was not found in African-Americans. Taken together, the results suggest race differences in how SCCs are reported, and how SCCs are associated with more objective measures of performance. Moving forward, researchers might consider the utility of SCCs in subgroups of interest. Understanding the utility of specific SCCs in racially diverse groups—as well as other assessments that rely on subjective reports—could inform and clarify study efforts that rely on participant reports as key outcomes, especially ongoing AD prevention trials. Ultimately, better characterisation of the utility of SCCs among diverse groups may benefit the accuracy of subjective reports in predicting cognitive decline.

Key points.

  • Subjective cognitive concerns are associated with objective memory.

  • Cognitive concerns may differ as a function of race.

  • Concerns relate to memory, but only for Caucasians.

  • African-Americans may endorse cognitive concerns differently than Caucasians.

Supplementary Material

Supplementary Data
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Supplementary Data
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Supplementary data

Supplementary data are available at Age and Ageing online.

Conflicts of interest

None.

Funding

Supported by NIH grant P01AG036694. R.A.S. was supported by K24AG035007. R.E.A. was supported by Alzheimer Association NIRG-12-243012 and NIH grant K23AG044431. The authors declare that they have no competing financial interests.

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