A study led by an Indian-origin scientist has found that people with coronary heart disease have an increased risk of developing dementia.
Dr Archana Singh-Manoux a Senior Research Fellow at University College London (UK) and INSERM (Institut national de la santé et de la recherche médicale) has found that heart disease patients are likely to have impaired cognition in terms of reasoning, vocabulary and verbal fluency.
"It is important to elucidate the link between these two diseases," said Singh-Manoux.
"The prevalence of dementia rises with age, doubling every four to five years after the age of 60, so that over a third of people older than 80 are likely to have dementia," she added.
The study involving 5837 middle-aged Whitehall civil servants revealed that the longer it took for heart disease to be diagnosed, the worse the person's cognitive performance. This effect was particularly marked in men.
"This is 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," she said.
"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.
"The major risk factors for CHD are cigarette smoking, diabetes, high cholesterol levels and high blood pressure. All of these are modifiable, and smoking, diet and physical exercise are key targets for prevention," she added.
She said that the results on the link between CHD and cognition underline the importance of these preventive measures by highlighting the impact of these risk factors not only on CHD but also on people's cognitive functioning.
During the study, Singh-Manoux measured the patients' verbal and mathematical reasoning, vocabulary, verbal fluency and short-term verbal memory. They also measured global cognitive status using a mini-mental-state-examination (MMSE).
They assessed CHD events, including non-fatal myocardial infarction and definite angina. The date of the cognitive testing was used to classify the first CHD event as having occurred within the last five years, between five to ten years ago, or over ten years ago.
The team found that that among both men and women with CHD scored poorly for reasoning, vocabulary and their global cognitive status (MMSE), when compared to people who had no CHD history. In women, these effects were also seen for verbal fluency.
"It is possible that shared risk factors drive this association. It is also possible that heart disease influences cognition through cerebral embolism or decreased cerebral perfusion," said Singh-Manoux.
The study is published online in Europe's leading cardiology journal, the European Heart Journal