Background
Cancer-related cognitive decline refers to subjective or objective cognitive deterioration in cancer patients after they are diagnosed or receiving treatment; it occurs in approximately 10–50% of cancer patients [
1]. Many patients are concerned about the adverse effects of cognitive decline, which may affect their lives and work [
2]. The factors that lead to cancer-related cognitive decline are not noticeably clear, and some factors, such as fatigue or genes, are not easily modifiable. It is particularly important to explore factors that can be easily recognized and addressed.
Cognitive reserve, which is deemed as the adaptability of cognitive processes, can facilitate the stability of cognitive performance during pathological or physiological changes in the brain [
3]. It can protect against cognitive decline in older adults. By evaluating cognitive reserve, we may be able to identify patients receiving cancer treatment who are at risk for cognitive decline. Concurrently, improving cognitive reserve may be a way to address their cognitive decline. However, few studies have investigated the role of cognitive reserve, and those that have suggest that low cognitive reserve is associated with decreased cognitive function in cancer patients [
4,
5]. One of the reasons for the paucity of research on cognitive reserve in cancer patients is the lack of appropriate assessment tools. Previous studies that measured cognitive reserve in cancer survivors used the Wide Range Achievement Test Reading Subscale; however, it is tedious to administer in clinical settings and is not designed to measure cognitive reserve.
Cognitive reserve is viewed as an active process that can be improved through lifetime experiences. These reserve-related factors across the lifespan mainly include educational attainment, occupation, and leisure activities [
6]. Some instruments have been developed to measure cognitive reserve by referencing reserve-related factors; however, no Chinese version is available. In addition, some instruments are not suitable for clinical practice or interventions because they are time-consuming, or do not include modifiable factors of cognitive reserve that can be addressed. Furthermore, almost all these tools are designed for older adults, with a lack of measures for younger adults. Yet, cognitive complaints also occur in young cancer patients. The Cognitive Reserve Assessment Scale in Health (CRASH) was developed by Amoretti et al. to assess cognitive reserve in Spanish adults and seniors [
7]. It was originally and specifically developed for patients with severe mental illness. It is based on the active model of cognitive reserve [
3], including education, occupation, and leisure activities across the phases of life. The CRASH can be used to assess the effectiveness of an intervention in improving cognitive reserve. It takes approximately 10 minutes to complete and can be easily administered by health workers in different professional fields (e.g., nurses, doctors, and psychologists).
The present study aimed to develop the Chinese version of the CRASH by translating it into Chinese and adapting it cross-culturally. In addition, we tested the tool’s psychometric properties including validity (structural validity and concurrent validity), reliability (internal consistency, test-retest reliability, and measurement error), and floor/ceiling effects in patients with cancer, according to the COnsensus-based Standards for the Selection of Health Measurement Instruments checklist (COSMIN) [
8]. In the concurrent validity testing, we tried to investigate the associations between objective cognitive function assessed by neuropsychological tests and subjective cognitive function assessed by cognitive reports. We hypothesized that the strength of the association between the CRASH score and objective cognitive function would be greater than that between the CRASH score and subjective function because the subjective cognitive function is more readily influenced by what and how many things cancer patients do in their daily lives.
Discussion
In the present study, we translated the CRASH from English into Chinese and adapted it for the Chinese context. We examined the tool’s psychometric properties with reference to the COSMIN by administering the scale to patients with cancer. Our results showed sufficient validity (structural and concurrent validity), good reliability (internal consistency, test-retest reliability, and measurement error), and no floor or ceiling effects.
The CFA on the Chinese CRASH items assessed the fit of the measurement model developed initially by Amoretti et al. [
7] using the Spanish CRASH, and the model fit indices showed that the fit was good. In addition, the standard factor loadings of all items were above 0.4 with
p < .001, indicating that the items grouped into the four domains can be considered acceptable.
Our results for concurrent validity suggested that a higher total score of the CRASH was associated with better performance on AVLT-I, STT-B, DST-forward, DST-backward, and VFT when controlling for factors related to cognitive function. This was consistent with the results of the original English CRASH that the score of the English version was associated with the performance of neuropsychological tests on attention, verbal fluency, verbal memory, and processing speed [
29]. The correlation analysis showed that the total score of the CRASH had a medium relationship with executive function, verbal fluency, attention, and working memory and a small relationship with short-term memory and delayed recall. Among the CRASH domains, education was the most related to cognitive performance and had a medium relationship with all neuropsychological test scores. Occupation had a small relationship with executive function and verbal fluency and a medium relationship with attention and working memory. Sociability had a medium relationship with short-term memory. Leisure activities had a small relationship with executive function, attention, and working memory and a medium relationship with verbal fluency.
Unlike the original scale, we added a multiple linear regression analysis to demonstrate that cognitive reserve measured by the Chinese CRASH is still associated with cognitive function after controlling for factors that affect cognitive function. The results of the regression models showed that when controlling for age, gender, fatigue, depression, and anxiety, the CRASH total score was associated the most with verbal fluency (β=0.39,
P<0.001) and was also significantly associated with short-term memory, delayed recall, executive function, attention, and working memory. Among the CRASH domains, education and sociability were mostly associated with cognitive function. Education was more associated with verbal fluency (β = 0.41,
p < 0.001) than other cognitive functions, as were leisure activities (β = 0.37,
p < 0.01). Sociability was most significantly associated with short-term memory (β = 0.42,
p < 0.01) and had relatively large associations with processing speed (β = -0.40,
p < 0.001) and executive function (β = -0.40,
p < 0.001). Occupation appeared to be the least associated with cognitive function and only with working memory. Modifiable factors of the CRASH, such as current leisure activities and sociability, were associated with different aspects of neuropsychological performance. Current sociability was mostly associated with short-term memory (β = 0.43,
p < 0.001), attention (β = -0.38,
p < 0.01), and executive function (β = -0.38,
p < 0.001). Yet, current leisure activities tended to be associated with verbal fluency (β = 0.34,
p < 0.01). Thus, interventions developed to enhance cognitive reserve modifiable factors may prevent or delay cognitive decline in patients with cancer. However, no statistically significant associations were found between the CRASH scores and subjective cognitive function (PCI and PCA). The discrepancy in performance between subjective and objective cognitive function in cancer survivors was reported in several studies [
30]. One possible explanation for our results is that subjective cognitive function is influenced to a certain extent by the difficulty and quantity of things that individuals usually do. Many participants informed us that they did not need to be involved in home or work activities as their families encouraged them to rest. They may not subjectively notice changes in their cognitive function due to uncomplicated daily activities. However, neuropsychological tests could reveal impaired cognitive function when patients must perform complicated tasks.
The reliability of the Chinese version of the CRASH was good, as demonstrated by acceptable internal consistency, excellent test-retest reliability, and acceptable measurement error [
22]. Regarding the internal consistency, the standardized Cronbach’s alpha and standardized McDonald's omega of the whole CRASH (0.83 and 0.70, respectively), domains of education (0.80 and 0.80, respectively), and sociability (0.94 and 0.95, respectively) were good. The Cronbach’s alpha for the occupation domain (0.64) seemed to be slightly low according to the widely accepted alpha value of 0.70. This may be because the number of occupation items (two) was too small to calculate a high Cronbach’s alpha. The Cronbach’s alpha is easily affected by the number of items, and the fact that Cronbach’s alpha was smaller due to fewer items does not mean that the internal consistency is low. In fact, McDonald's omega is not affected by the number of items, and the omega value of 0.77 for the occupation domain suggested good internal consistency. Both the standardized Cronbach’s alpha and McDonald's omega of the leisure activities domain were somewhat small (0.65 and 0.66, respectively). The reason for this may be the differences in participation between life stages, especially between childhood and adulthood. Although the internal consistency value, which was less than 0.70 but more than 0.65, was acceptable in some literature [
31], it needs to be further tested in a larger sample. Therefore, in general, the internal consistency of the Chinese CRASH is acceptable except for the leisure activities domain which is a little low. As for the original English CRASH, the authors only tested the internal consistency of the whole CRASH with the Cronbach’s alpha being 0.903, which was higher than the Chinese one. Furthermore, the ICC values of the total scale and each domain (0.914–0.993) showed excellent test-retest reliability [
25]. The measurement error was acceptable, as the SDC (4.914) was smaller than nine (10% of the CRASH total score) [
27]. Finally, the CRASH showed no floor or ceiling effects in our sample.
However, there are limitations to our study. First, the internal consistency of the CRASH leisure activities domain is somewhat low. Second, we did not examine the convergent validity or known-groups validity as there were no other Chinese instruments to assess cognitive reserve, and this also made it impossible to compare the relevant results to the original CRASH. In addition, unlike psychiatric disorders, the disease or therapeutic factors that can distinguish between high and low cognitive reserve are unclear, which also limited us from assessing the known-groups validity. Third, we did not examine the inter-rater reliability or sensitivity to change, which must be remedied in the future validation of the scale. Fourth, most of the participants grew up when China's economy was in bad shape (born before 1970), but the scale needs to be validated in a larger sample with a younger population as China's economy has grown exponentially in recent years and individual’s education and leisure patterns have changed dramatically. Fifth, we did not collect demographic or clinical information on the patients who refused to participate in our study and could not compare whether there were differences in demographic or clinical characteristics between them. The fact that the patients refused to participate in our study mainly because of physical or psychological discomfort reflects a potential selection bias that we may have had in recruiting participants.
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