Twinning hearts and minds

Update on the NAS-NRC Twin Registry

The National Academy of Sciences-National Research Council (NAS-NRC) Twin Registry is one of the oldest, national population-based twin registries in the United States. It consists of 15,924 white male twin pairs born in the years 1917 to 1927 (inclusive), both of whom served in the armed forces, mostly during World War II. This article updates activity in this registry since the earlier 2002 article in Twin Research. The results of clinically based studies on dementia, Parkinson's disease, age-related macular degeneration, and primary osteoarthritis were published, as well as articles based on previously collected questionnaire data on chronic fatigue syndrome, functional limitations, and healthy aging. In addition, risk factor studies are being planned to merge clinical data with earlier collected risk factor data from questionnaires. Examination data from the subset of National Heart, Lung, and Blood Institute (NHLBI) twins resulted in a number of articles, including the relationship of endogenous sex hormones to coronary heart disease and morphological changes in aging brain structures. The NEO Five-Factor Personality Inventory (a paper-and-pencil self-administered questionnaire) has been fielded for the first time. A push to consolidate the various data holdings of the registry is being made.

History of coronary heart disease and cognitive performance in midlife: the Whitehall II study

AIMS

Some studies show coronary heart disease (CHD) to be a risk factor for cognitive function while others report no association between the two. We examined the effect of CHD history and duration on cognition in a middle-aged population.

METHODS AND RESULTS

Data come from the Whitehall II study of 10,308 participants (33% women), aged 35-55 years at baseline (Phase 1; 1985-88). CHD events were assessed up to Phase 7 (2002-04) when 5837 participants (28.4% women) undertook six cognitive tests: reasoning, vocabulary, phonemic and semantic fluency, memory and the mini-mental-state-examination (MMSE); standardized to T-scores (mean = 50, standard deviation = 10). Analysis of covariance was used first to model the association between CHD history and cognition and then to examine the effect of time since first CHD event (in the last 5 years, 5-10 years ago, >10 years ago). Among men, in analyses adjusted for age, education, marital status and medication for cardiovascular disease, CHD history was associated with lower T-scores on reasoning [-1.16; 95% confidence interval (CI) = -2.07, -0.25], vocabulary (-2.11; 95% CI = -3.01, -1.21), and the MMSE (-1.45; 95% CI = -2.42, -0.49). In women, these effects were also evident for phonemic and semantic fluency. Among men, the trend within CHD cases suggested progressively lower scores on reasoning, vocabulary and semantic fluency among those with longer duration of CHD.

CONCLUSION

Our findings go some way towards suggesting an association between CHD history and cognitive performance in middle-aged adults.

Association of neurocognitive function and quality of life 1 year after coronary artery bypass graft (CABG) surgery

OBJECTIVE

Although coronary artery bypass grafting (CABG) has been shown to improve quality of life and functional capacity for many patients, recent studies have demonstrated that a significant number of patients exhibit impairment in cognitive function immediately following surgery and beyond. We sought to determine the impact of this postoperative cognitive dysfunction on quality of life (QOL) and to characterize the dysfunction from the patient's perspective.

METHODS

With Institutional Review Board (IRB) approval and written informed consent, 732 patients at Duke University Hospital undergoing CABG were enrolled. Five hundred fifty-one (75%) completed baseline, 6-week, and 1-year neurocognitive tests and psychometric measures designed to assess QOL. Neurocognitive status was assessed by a composite cognitive index score representing the mean of the scores in four cognitive domains. Change in QOL was assessed by subtracting baseline from 1-year scores for each of 10 QOL measures. The association between QOL and cognitive dysfunction was investigated using multivariable linear regression analysis.

RESULTS

Cognitive decline limited improvement in QOL, with substantial correlation between change in cognition and change in QOL. One-year QOL measures are associated with both 6-week and 1-year change in cognition (Instrumental Activities of Daily Living, p < .0001; Duke Activity Status Index, p < .02; Cognitive Difficulties, p < .0001; Symptom Limitations, p = .0001; Center for Epidemiologic Study Depression, p < .0001; General Health Perception, p = .0001).

CONCLUSIONS

Postoperative cognitive decline may diminish improvements in QOL. Strategies to reduce cognitive decline may allow patients to achieve the maximum improvement in QOL afforded by CABG, as even short-term cognitive dysfunction has implications for QOL 1 year later.