Villejuif Cedex, France - Patients with coronary heart disease are more likely to show reduced cognitive function in late middle age than those without heart disease, a new study has found [1]. And cognitive function was worst in patients with the earliest diagnosis of CHD.

"Although our results do not prove that coronary heart disease causes reduced cognitive function, we have shown a strong link, and it is likely that the risk factors for heart disease are also risk factors for cognitive function," lead author Dr Archana Singh-Manoux (INSERM, Villejuif Cedex, France) commented to heartwire. "Our results should be an added incentive for controlling these risk factors, such as bad diet, sedentary lifestyle, smoking, blood pressure, and lipids. We know these things contribute to heart disease, and now we suspect they also contribute to cognitive decline," she added.

The latest findings, published online July 23, 2008 in the European Heart Journal, come from the Whitehall II study, which followed 10 308 civil servants based in London, UK, with an average age of around 40 at the start in 1985. Baseline screening involved a clinical examination, including biochemical measurements, and a questionnaire on demographic characteristics, health, lifestyle factors, work characteristics, social support, and life events. Six subsequent data collections have taken place involving either questionnaires alone or questionnaire plus a clinical examination. In the most recent evaluation (2002-2004), 5837 participants undertook six cognitive tests: reasoning, vocabulary, phonemic and semantic fluency, memory, and the Mini-Mental State Examination (MMSE).

For the purpose of this study, the authors recorded the time of the first CHD event, defined as nonfatal MI or definite angina (found from data from questionnaires and corroborated by medical records), and examined whether this correlated with cognitive function at the 2002-2004 screening, when the participants had an average age of about 60. The analyses adjusted for age, education, marital status, and medication for cardiovascular disease.

Results showed that among men, CHD history was associated with lower scores for reasoning, vocabulary, and the MMSE. And 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.

The authors note that while dementia occurs late in life, it is increasingly recognized that there is a long preclinical phase characterized by progressive neuropathological changes that then become clinically detectable as cognitive deficit or dementia and that this "lifelong" view of dementia stresses the importance of risk factors in midlife. "Our core hypothesis is that cognitive decline starts earlier in life than widely accepted, so identifying risk factors for this cognitive decline is vitally important," Singh-Manoux commented to heartwire. "We have shown that if you get CHD you are more likely to suffer reduced cognitive function. We don't know that this will definitely translate into dementia, but we believe it is likely that this would be the case."

Singh-Manoux said that this was the first large study to examine the association between coronary heart disease and cognition. "Until now, research on the link between cardiovascular disease and dementia has focused more on cerebrovascular disease than CHD. However, it is CHD and not cerebrovascular disease that makes up the bulk of cardiovascular disease and is a major health problem in the developed world," she commented. "Our results should give an added incentive to reduce the risk factors for CHD, as by so doing we could also be reducing the chances of cognitive decline," she noted.

Singh-Manoux said she and her fellow researchers are continuing to follow the study participants, and they plan to conduct further cognitive function testing to look for further cognitive decline and dementia. "This is always problematic, as people with the poorest cognition are the most difficult to keep track of, and they tend to be the ones who drop out. As a result, these associations are always underestimated, but we are doing our best to try and pick these people up," she added.