M.P.J. van Boxtel

Dietary intake of fatty acids and fish in relation to cognitive performance at middle age

Objective: To examine the associations of fatty acid and fish intake with cognitive function. Methods: Data are from a cross-sectional population-based study among 1,613 subjects ranging from 45 to 70 years old. From 1995 until 2000, an extensive cognitive battery was administered and compound scores were constructed for memory, psychomotor speed, cognitive flexibility (i.e., higher order information processing), and overall cognition. A self-administered food-frequency questionnaire was used to assess habitual food consumption. The risk of impaired cognitive function (lowest 10% of the compound score) according to the energy adjusted intake of fatty acids was assessed with logistic regression, adjusting for age, sex, education, smoking, alcohol consumption, and energy intake. Results: Marine omega-3 polyunsaturated fatty acids (PUFA) (eicosapentaenoic acid and docosahexaenoic acid) were inversely related to the risk of impaired overall cognitive function and speed (per SD increase: OR = 0.81, 95% CI 0.66 to 1.00 and OR = 0.72, 95% CI 0.57 to 0.90). Results for fatty fish consumption were similarly inverse. Higher dietary cholesterol intake was significantly associated with an increased risk of impaired memory and flexibility (per SD increase: OR = 1.27, 95% CI 1.02 to 1.57 and OR = 1.26, 95% CI 1.01 to 1.57). Per SD increase in saturated fat intake, the risk of impaired memory, speed, and flexibility was also increased, although not significantly. Conclusions: Fatty fish and marine omega-3 PUFA consumption was associated with a reduced risk and intake of cholesterol and saturated fat with an increased risk of impaired cognitive function in this middle-aged population.

Inflammation markers in relation to cognition in a healthy aging population.

The relation between serum inflammatory protein levels and cognitive performance was investigated in a healthy population. Individuals were tested during 6 years of follow-up. Serum concentrations of 10 inflammatory proteins were correlated to cognitive speed (Letter-Digit Coding Test, LDCT), attention and information processing (Stroop) and memory (Word Learning). Haptoglobin levels at baseline correlated negatively with cognitive performance on the Stroop and Word Learning Recall test over the 6 years follow-up period. C-reactive protein (CRP) levels at baseline correlated negatively with performance on the Word Learning tests over the 6 years follow-up period. Thus, relatively high concentrations of haptoglobin and C-reactive protein may be indicative for impaired cognitive performance.

Cognitive interventions in healthy older adults and people with mild cognitive impairment: a systematic review.

Given that the research area of cognitive intervention studies in the aging population is growing rapidly, it is important to review and gauge more recent intervention studies, in order to determine the evidence for the effectiveness of cognitive interventions. The purpose of the present review was to update the recent systematic reviews of Papp et al. (2009) and Martin et al. (2011), to evaluate the effectiveness of cognitive interventions in healthy older adults and people with MCI, by taking into account the methodological quality of the interventions studies. A systematic review of randomized controlled trials (RCT) and clinical studies published between August 2007 and February 2012 in Pubmed and PsychINFO was performed. The quality of the included RCTs was assessed according to the CONSORT criteria for RCTs. A total of thirty-five studies were included; twenty-seven RTCs and eight clinical studies. The content of the intervention studies differed widely, as did the methodological quality of the included RCTs, but was considerably low with an average of 44% of the Consort items included. The results show evidence that cognitive training can be effective in improving various aspects of objective cognitive functioning; memory performance, executive functioning, processing speed, attention, fluid intelligence, and subjective cognitive performance. However, the issue whether the effects of cognitive interventions generalize to improvement in everyday life activities is still unresolved and needs to be addressed more explicitly in future research.

Cognitive functioning in healthy older adults aged 64-81: a cohort study into the effects of age, sex, and education.

ABSTRACT The objective of this study was to determine a possible differential effect of age, education, and sex on cognitive speed, verbal memory, executive functioning, and verbal fluency in healthy older adults. A group of 578 healthy participants in the age range of 64–81 was recruited from a large population study of healthy adults (Maastricht Aging Study). Even in healthy individuals in this restricted age range, there is a clear, age-related decrease in performance on executive functioning, verbal fluency, verbal memory, and cognitive speed tasks. The capacity to inhibit information is affected most. Education had a substantial effect on cognitive functioning: participants with a middle or high level of education performed better on cognitive tests than did participants with a low level of education. Women performed better than men on verbal memory tasks. Therefore, education and sex must be taken into account when examining an older individuals cognitive performance.

The relation between global and limbic brain volumes on MRI and cognitive performance in healthy individuals across the age range

The present study investigated the range of age-related changes in brain morphology and the relation with performance on memory and other cognitive tests in a healthy population. A group of 61 subjects (21 to 81 years old, mean = 55.7), free from cognitive and medical deficits, underwent MRI scanning and neuropsychological assessment encompassing memory and other cognitive tests. Volumetry of the hippocampus, parahippocampal gyrus, mamillary bodies, third ventricle, and total brain matter was performed. The results indicate that in healthy individuals increases in ventricular volume and volume decreases in total brain matter, hippocampus and parahippocampal gyrus, but not mamillary bodies, are clearly apparent with increasing age. However, no relation could be established between the brain volumes and test performance when controlling for the effects of age. To conclude, variations in total and limbic brain volumes do not seem predictive for cognitive performance independent of age.

Predictors of attrition in a longitudinal cognitive aging study: the Maastricht Aging Study (MAAS).

A large sample of older participants of the Maastricht Aging Study (MAAS) were compared to drop-outs at the 3-year follow-up with respect to socio-demographic, health, and cognitive characteristics. In addition, the impact of selective drop-out on measures of cognitive change was examined. To this end, hypothetical scores were estimated for drop-outs by using single and multiple imputation methods. Of the initial sample of 539 subjects, aged 49 years and older at baseline, 116 (22 %) did not return for the follow-up (n = 32 had died, n = 84 refused participation). Drop-outs who refused to participate in the follow-up were more often women, had lower educational levels, and had lower baseline scores on neurocognitive tests. Follow-up drop-outs who had died were more often men, older, and had a poorer performance on cognitive tests than the follow-up participants. Although follow-up participants and drop-outs differed in terms of socio-demographic and cognitive characteristics, attrition appeared to have little effect on the estimates of cognitive change.

The effects of habitual caffeine use on cognitive change: a longitudinal perspective

The efficiency of higher cortical functions, such as memory and speed of complex information processing, tends to decrease with advancing age in normal healthy individuals. Recently, a high habitual intake of caffeine was found associated with better verbal memory performance and psychomotor speed in several cross-sectional population studies. We tested the hypothesis that habitual caffeine intake can reduce or postpone age-related cognitive decline in healthy adults. For this purpose, the cognitive performance of all participants in the Maastricht Aging Study (MAAS), aged between 24 and 81 years, was reassessed after 6 years. Information on the intake of caffeine-containing beverages was available from the baseline questionnaire. After 6 years, 1376 (75.6%) individuals were available for reassessment. After correction for demographic characteristics, baseline performance and health status, there were small albeit significant associations between the overall estimated caffeine intake at baseline and the 6-year change in complex motor speed (motor choice reaction time). The earlier found association between caffeine intake and verbal memory performance was not apparent in this longitudinal study. These results imply that the longitudinal effect of habitual caffeine intake is limited and will not promote a substantial reduction in age-related cognitive decline at a population level.

Ambulatory blood pressure, asymptomatic cerebrovascular damage and cognitive function in essential hypertension

Prolonged exposure to elevated blood pressure (BP) can lead to both structural (white matter lesions (WML) or infarctions) and functional changes in the brain. We studied in previously diagnosed essential hypertensive individuals if diurnal BP variation and ambulatory BP (ABP) profile (daytime, night time and 24-h BP averages) were related to evidence of WML, the presence of ‘silent’ infarcts, and cognitive performance. A group of 86 patients (mean age 57.4±10 years, range 40–80) were first screened for hypertension-related organ damage and underwent 24-h ABP monitoring, magnetic resonance imaging (MRI) of the brain, and a comprehensive neurocognitive assessment. Age and ABP profile were related to more periventricular, but not subcortical, WML and to presence of lacunar infarctions on MRI. After correction for demographical group differences, no association was found between night time dipping of BP on the one hand and both WML load and cognitive parameters (verbal memory, sensorimotor speed, cognitive flexibility) on the other. The presence of lacunar infarctions, however, predicted lower performance on verbal memory. Furthermore, daytime and 24-h pulse pressure averages were associated with pWML, whereas systolic BP and mean arterial pressure (MAP) for daytime, night-time and 24-h periods were higher in patients with lacunar infarctions. Notwithstanding the large variability of WML in this sample, the evidence of a connection between diurnal BP variation and early target organ damage in the brain was not convincing. However, the ABP profile may be predictive of cerebral lesion type.

Mild Hearing Impairment Can Reduce Verbal Memory Performance in a Healthy Adult Population

We studied to what extent immediate and delayed recall in an auditory verbal learning paradigm was affected by basic information processing speed (digit copying) and hearing acuity (average hearing acuity at 1, 2 and 4 KHz at the better ear). A group of 453 individuals in the age between 23 and 82 years with no overt hearing pathology was recruited from a larger study of cognitive aging (Maastricht Aging Study, MAAS). After controlling for age, sex, educational level, and processing speed it was found that a mild to moderate hearing loss predicted lower verbal memory performance. Auditory administered verbal memory tests can underestimate true memory performance, particularly in older individuals with unknown hearing status.

Combination of serum markers related to several mechanisms in Alzheimer’s disease

Alzheimers disease (AD) probably involves several pathobiochemical mechanisms and this may be reflected by changes in different serum components. The present study investigated whether the combined analysis of serum molecules related to different mechanisms improves the discrimination of AD patients from healthy controls. Serum of patients with AD was analyzed for a broad spectrum of marker molecules, including 11 inflammatory proteins, 12 sterol intermediates and phytosterols, 2 brain-specific proteins and 4 constituents involved in homocysteine homeostasis. The serum molecule concentrations were combined in a logistic regression model, using a forward stepwise inclusion mode. The results showed that the combination of interleukin-6 (IL-6) receptor, protein alpha1 fraction, cysteine and cholesterol concentrations improved the discrimination between AD patients and healthy controls compared to the single markers. In conclusion, the results of this study have shown that the complex pathology in AD is reflected in a pattern of altered serum concentrations of several marker molecules related to several pathobiochemical mechanisms.