ذخیره شناختی و ناتوانی در ادراک بیماری در زوال عقل مشکوک و خفیف

Abstract Cognitive reserve (CR) theory posits that the clinical presentation of individuals with the same brain disease varies based upon premorbid variables (e.g., education, occupation, reading ability). Anosognosia (decreased insight regarding one's deficits) is common in dementia and has implications for safety, treatment, and caregiver burden. The current study examined the role of CR in anosognosia in individuals with mild dementia. Participants were individuals diagnosed with questionable or mild dementia (Clinical Dementia Rating 0.5 or 1) after neuropsychological evaluation. Anosognosia was measured by informant–patient discrepancy on the Cognitive Difficulties Scale. High and Low CR groups were created based upon reading performance. Low CR showed greater anosognosia than High CR. Anosognosia was associated with reduced reading performance, even after controlling for global cognitive decline. These findings suggest CR is related to anosognosia in questionable and mild dementia, and have clinical implications for the assessment of awareness in dementia.

2. Results 2.1. Participant differences Significant differences between the High and Low CR groups emerged for level of education, F (1, 75) = 14.67, P < .01, with higher education in the High CR group, providing evidence for divergent validity of the High versus Low CR groups. The groups did not differ significantly on age, gender, race, or CDR rating. In addition, an unexpected finding of different informant type in the groups was detected; whereas the spouse was most often the informant for the High CR group, a child or other close friend or relative was more likely to be the informant for the Low CR group, χ2 (1, n = 76) = 9.45, P < .01 (see Table 1 for descriptive demographic information). Because of this finding, we included informant type in the analysis of the main outcome (described in the following section). Table 1. Demographic characteristics of the sample Low CR (n = 36) High CR (n = 40) M S.D. M S.D. Education* 11.89 2.97 14.38 2.69 Age 74.06 7.91 74.13 6.45 CDR rating 0.5 n = 12 n = 22 1.0 n = 24 n = 18 Gender Male n = 20 n = 20 Female n = 16 n = 23 Informant* Spouse n = 9 n = 24 Child/other n = 27 n = 16 Race Caucasian n = 36 n = 38 Asian American n = 0 n = 1 Latin American n = 0 n = 1 * Significant with P < .01, two-tailed. Table options 2.2. Correlations between CDS and 3MS/MMSE, and WRAT reading and education: manipulation checks of anosognosia and cognitive reserve measures To establish that informant ratings of cognitive difficulties were in fact more accurate than patient ratings, correlations between MMSE/3MS scores and CDS ratings were calculated. As expected, informant ratings significantly correlated with performance on the MMSE (r = −.30, P < .01) and 3MS (r = −.34, P < .01), indicating that greater report of cognitive impairment by the informant was associated with poorer cognitive performance. In contrast, patient self-ratings were uncorrelated with performance on MMSE (r = .01, P = ns) or 3MS (r = −.08, P = ns). This finding generally held true in the High and Low CR groups as well (see Table 2), suggesting informant ratings were more accurate than patient ratings, and lending validity to the use of CDS discrepancy to measure anosognosia. A significant correlation was found between WRAT reading and years of education(r = .53, P < .01), providing evidence of convergent validity for WRAT reading as a CR measure. This finding held true in the High CR group (r = .51, P < .01), but did not in the Low CR group (r = .13, P = ns), suggesting that CR groups derived from educational attainment would not be equivalent to those based on reading performance. Table 2. Correlation between patient and family CDS ratings and MMSE/3MS scores Patient CDS Informant CDS Low CR group MMSE 0.07 −0.27* 3MS −0.20 −0.43*** High CR group MMSE −0.11 −0.29** 3MS −0.06 −0.18 * P = .06 (trend). ** P < .05. *** P < .01 (all one-tailed). Table options 2.3. Anosognosia differences in Low CR versus High CR groups To address the previously described informant differences (spouse vs. other), a 2 × 2 (CR group by informant type) factorial analysis of variance was conducted on anosognosia. As expected, there was a main effect of CR group status on anosognosia, with the High CR group showing a significantly lower discrepancy, F (1, 75) = 8.44, P < .01, between participant and family ratings, indicating better awareness of cognitive difficulties (High CR: M = .04, S.D. = .91; Low CR: M = .59, S.D. = .92). There was no main effect of informant type (i.e., spouse vs. child/other) on level of awareness, F (1, 75) = 0.15, P = ns, and no interaction between informant type and CR group on level of awareness, F (1, 75) = 0.01, P = ns. A partial correlation between WRAT reading performance and anosognosia, controlling for 3MS performance, revealed that increased awareness was associated with better reading performance after controlling for global cognitive decline (pr = .31, P < .01). 2.4. CDS exploratory item analyses Exploratory one-sample t tests were used to examine discrepancy scores for individual CDS items in both the High and Low CR groups. After Bonferroni correction, the Low CR group showed significant discrepancies for eight CDS items (P ≤ .001) (see Table 3), whereas the High CR group showed no significant discrepancies between informant and patient for any CDS item. Among the CDS items showing significant discrepancies in the Low CR group, the predominant themes were memory and communication difficulty. Table 3. CDS items showing a significant discrepancy between informant and patient Low CR High CR CDS item M S.D. t (35) M S.D. t (39) Forgets appointments, dates, etc. 1.08 1.63 3.99* 0.40 1.60 1.58 Forgets to return phone calls 0.94 1.45 3.90* 0.10 1.34 0.47 Trouble describing a television program 0.86 1.38 3.75* 0.13 1.38 0.57 Doesn’t say what she/he means 1.06 1.35 4.69* 0.05 1.04 0.31 Trouble getting out tip of tongue information 0.89 1.14 4.68* 0.10 1.10 0.57 Forgets what day of the week it is 0.86 1.46 3.55* 0.08 1.59 0.30 Forgets to pay bills, record checks, etc. 0.86 1.48 3.50* −0.20 1.09 −1.16 Mind goes blank at times 0.78 1.31 3.56* 0.08 1.23 0.39 * Significant after Bonferroni correction with P ≤ .001 (two-tailed).