To determine the size of the impairment across different cognitive domains in preclinical Alzheimer's disease (AD), a meta-analysis based on 47 studies involving 9,097 controls and 1,207 preclinical AD cases was conducted. There were marked preclinical deficits in global cognitive ability, episodic memory, perceptual speed, and executive functioning; somewhat smaller deficits in verbal ability, visuospatial skill, and attention; and no preclinical impairment in primary memory. Younger age (< 75 years) and shorter follow-up intervals (< 3 years) were associated with larger effect sizes for both global cognitive ability and episodic memory. For global cognitive ability, studies that used population-based sampling yielded larger effect sizes; for episodic memory, larger differences were seen in studies that preidentified groups in terms of baseline cognitive impairment. Within episodic memory, delayed testing and recall-based assessment resulted in the largest effect sizes. The authors conclude that deficits in multiple cognitive domains are characteristic of AD several years before clinical diagnosis. The generalized nature of the deficit is consistent with recent observations that multiple brain structures and functions are affected long before the AD diagnosis.
The epsilon4 allele of the apolipoprotein E (APOE) gene is a known risk factor for Alzheimer's disease and may also affect cognitive performance in normal aging. Evidence of the presence and magnitude of epsilon4-related cognitive deficits was examined with a meta-analysis of the available literature. Thirty-eight studies were included, and cognitive performance was collapsed into 8 domains. Results indicated significant APOE-epsilon4 group differences for global cognitive functioning, episodic memory, and executive functioning, in favor of non-epsilon4 carriers. In addition, older age and APOE-epsilon4 heterozygosity was associated with smaller epsilon4-related impairments. The meta-analysis results suggest that APOE-epsilon4 genotype does affect cognitive performance in healthy aging, although the influence is relatively small and specific to certain domains of cognitive performance.
Purpose: Evidence is mixed regarding long-term cognitive deficits in patients treated with chemotherapy. Previous meta-analyses have not focused specifically on the postchemotherapy period and have not incorporated several recent studies. The goal of the current study was to conduct a meta-analysis of cognitive functioning in breast cancer survivors who were treated with chemotherapy ≥ 6 months previously. Methods: A search of PubMed, PsycInfo, Cumulative Index to Nursing and Allied Health Literature, and Cochrane Library yielded 2,751 abstracts, which were independently evaluated by pairs of raters. Meta-analysis was conducted on 17 studies of 807 patients previously treated with standard-dose chemotherapy for breast cancer. Neuropsychological tests were categorized according to eight cognitive domains: attention, executive functioning, information processing, motor speed, verbal ability, verbal memory, visual memory, and visuospatial ability. Results: Deficits in cognitive functioning were observed in patients treated with chemotherapy relative to controls or prechemotherapy baseline in the domains of verbal ability (g = −0.19; P < .01) and visuospatial ability (g = −0.27; P < .01). Patients treated with chemotherapy performed worse than noncancer controls in verbal ability and worse than patients treated without chemotherapy in visuospatial ability (both P < .01). Age, education, time since treatment, and endocrine therapy did not moderate observed cognitive deficits in verbal ability or visuospatial ability (all P ≥ .51). Conclusion: Results indicate that, on average, observed cognitive deficits in patients with breast cancer previously treated with chemotherapy are small in magnitude and limited to the domains of verbal ability and visuospatial ability. This information can be used to inform interventions to educate patients with breast cancer regarding the long-term impact of chemotherapy on cognitive functioning.
Fatigue is among the most common and distressing symptoms experienced by cancer patients. This systematic review and meta-analysis evaluates the efficacy of psychological and activity-based interventions against cancer-related fatigue in cancer patients. MEDLINE, PsycINFO, and CINAHL. Randomized controlled trials of psychological and activity-based interventions involving adult cancer patients in which fatigue was an outcome were reviewed. Forty-one trials were reviewed and 30 were included in a meta-analysis. Fifty percent of psychological trials and 44% of activity-based trials rated fair or better in quality yielded significant findings favoring the intervention condition. Meta-analysis yielded an overall effect size of 0.09 (95% CI = .02- .16) favoring nonpharmacological conditions. Further analysis indicated that effect sizes were significant for psychological interventions (d-sub(w) = .10, 95% CI = .02-.18) but not activity-based interventions (d-sub(w) = .05, 95% CI = -.08 - .19). Findings provide limited support for use of nonpharmacological interventions to manage cancer-related fatigue. The lack of research with heightened fatigue as an eligibility criterion is a notable weakness of the existing evidence base.