Blood Pressure
Sleep & hardening of the arteries Blood pressure & cognitive function
Exercise and pre-eclampsia Blood pressure & Alzheimer's
Blood pressure linked to diet Salt intake & blood pressure in children
High levels of exercise may cause pre-eclampsia
Up until now, pregnant women have been advised to maintain a moderate level of physical activity throughout their pregnancy in order to help them stay healthy and to keep their blood pressure down. However, recent research (Osterdal et al. Does leisure time physical activity in early pregnancy protect against pre-eclampsia? British Journal of Obstetrics and Gynaecology, 2008) that attempted to prove this, has ended up DISPROVING it!
The study looked at medical data from 85,000 women and it showed that jogging for more than 1 hour and 15 minutes per week doubled the risk of developing pre-eclampsia - a form of high blood pressure that affects 1 in 14 pregnant women and is potentially fatal for mother and baby.
What's more, the researchers found that, as the level of exercise increased, so did the risk of pre-eclampsia. For those performing between 4.5 and 7 hours exercise per week, the risk of developing pre-eclampsia increased by 65% but performing over 7 hours of exercise per week increased the risk by 78%. This means that the overall risk of developing pre-eclampsia is 7% for women doing more than 1h15m exercise, 18% for those performing 4.5h to 7h exercise and 29% if they are doing over 7h exercise per week.
Current guidelines suggest that women maintain a moderate level of activity throughout pregnancy but this research seems to indicate that pregnant women should not perform more than 1h15m of higher intensity activity per week. More research now needs to be carried out to determine what is a safe exercise intensity and duration for pregnant women and whether the mode of exercise plays a part in pre-eclampsia risk too.
Blood pressure and Alzheimer's risk
An analysis of over 10 years of Alzheimer's research has found a significant link between blood pressure and the development of late-onset Alzheimer's (Alzheimer's Australia. Press Release. Latest Medical Finding - Reducing high blood pressure decreases incidence of dementia.). Results showed that successfully treating and lowering high blood pressure can reduce Alzheimer's disease by up to 50%.
This led Dr Michael Valenzuela, the researcher, to state that, "...the number one thing a person can do to help prevent dementia is to have your blood pressure checked regularly and, if it is high, take the right measures to bring it under control."
Dr Valenzuela theorises that high blood pressure reduces the blood flow to the memory part of the brain meaning that the brain cells do not receive enough nutrients and do not have their waste products removed effectively. This can lead to the blood vessels in this section of the brain bursting/bleeding which could set off the development of Alzheimer's.
Lack of sleep hardens the arteries
A recent study from America (King et al. Short sleep duration and incident coronary artery calcification. JAMA, 2008, 300, 2859-2866) has shown that those of us who sleep for less than 5 hours a night may be at an increased risk of developing calcium plaques in our arteries putting us at a higher risk of heart disease and heart attack.
The study found that almost one third of people who sleep less than 5 hours per night developed hardened arteries whereas just one tenth of people who sleep for 6 hours or more will develop this condition. The researchers concluded that, for every extra hour's sleep, the risk of developing hardened arteries dropped by 33%.
There are no firm conclusions as to why this link is evident. It could be due to the fact that blood pressure drops whilst we are asleep so a lack of sleep means that excess strain is placed on the arteries leading to the build up of plaques. Alternatively, it may be that the stress is the cause - stress hormones are linked with lack of sleep and hardening of the arteries.
Whatever the cause may be, the best advice that we can give you is to try to get at least 6 hours sleep per night!
Blood pressure impacts upon cognitive ability
A small study from December 2008 (Gamaldo et al. Exploring the within-person coupling of blood pressure and cognition in the elderly. Journal of Gerentology, 15 Dec 2008) found that high blood pressure may impact upon a person's cognitive ability. The researchers measured the subject's (36 people aged 60 - 87) blood pressure and cognitive functioning twice a day for 60 days.
Results showed that those people with s systolic blood pressure of over 130mmHg suffered a significant loss in cognitive ability when their blood pressure rose due to mental stress. However, subject with systolic blood pressure under 130mmHg did not suffer any decline in cognitive ability in the same situation despie a rise in their actual blood pressure at the time.
Researchers suggest that this study may explain why some people find it hard to function cognitively in high pressure situations. More work needs to be done in this area though as this study was small.
Blood pressure linked to diet for the first time
For the first time, blood pressure has been linked to diet by sicentists from Imperial College in London (Holmes et al, (2008). Human metabolic phenotype diversity and its association with diet and blood pressure. Nature, advance online publication, 20 April 2008).
The findings link blood pressure to an individual's 'metabolic fingerprint' - how they process food - and the results show that this is more important than genetics. It appears as if our diet and 'gut bugs' are more to blame than our genetics when it comes to developing hypertension.
The researchers found that certain metabolites found in urine are directly related to blood pressure. Metabolites are the by-products of metabolism - the breakdown of foods - and they act as markers which reveal how diet and lifestyle contribute to disease. The metabolites that are linked to high blood pressure are those that are produced when an individual's diet is rich in meat & alcohol and low in fibre. Therefore, this type of diet may increasee the risk of hypertension.
The study analysed the the 'metabolic fingerprints' of 4,630 middle aged adults in the UK, the USA, China and Japan. Interesting, the subjects from the UK and the USA have similar metabolic fingerprints which probably explains the similar incidences of high blood pressure and heart disease in these two countries.
Another interesting finding was that, although adults in Japan and the USA have different genetic profiles, Japanese people living in the USA have 'American metabolic fingerprints'. This shows that lifestyle, and in particular diet, is a dominant feature in determining metabolism.
The important message to come from this study is that although you cannot influence your genetics, you CAN influence your diet and this can have an impact upon your risk of developing hypertension. To reduce the risk of developing hypertension, this study suggests that people should limit their intake of meat and alcohol whilst increasing their intake of fibre.
Salt & blood pressure in children & adolescents
A study published in the Journal of Human Hypertension has shown that many children and adolescents would benefit from a reduction in their salt intake (He et al (2008). Salt and blood pressure in children and adolescents. Journal of Human Hypertension, 22, 4-11.)
The researchers studied a large amount of data from the 1997 British National Diet and Nutrition Survey for Young People which gathered information from 4 to 18 year olds. The average salt intake (not including salt added in cooking or at the table) was ~4.7g/day in 4 year olds and this increased to an intake of ~6.8g/day in 18 year olds.
Findings showed that there was a significant relationship between increased salt intake and increased systolic blood pressure. In fact, an increase of 0.1g/day of salt intake was related to an increase of 0.4mmHg in systolic blood pressure. This led researchers to conclude that a reduction in salt intake in children and adolescents would be of benefit to their blood pressure.
Statins may lead to a reduction in blood pressure
Research published in the Archives of Internal Medicine indicates that statins may reduce blood pressure in hypertensive patients as well as reducing cholesterol levels (Golomb et al (2008). Reductions in blood pressure with statins. Arch Intern Med. 2008, 168(7), 721-727.)
973 subjects took part in the study in which they were given either 20mg simvastatin, 40mg pravastatin sodium or a placebo for 6 months. Blood pressure was monitored throughout the trial and after the trial had ended to determine the time-course of any effects as well as the impact that removing the statin treatment had upon the individual's blood pressure.
Results showed that there was no impact upon blood pressure after just one month of medication. However, after 6 months, the statins had significantly reduced the participant's blood pressure as compared to the placebo - 2.2mmHg reduction in systolic blood pressure and 2.4mmHg reductionin diastolic blood pressure. 2 months after the trial had ended, blood pressure readings had returned to pre-trial levels with any reductions being lost.
There was no difference in results according to the type of statin being taken. Interestingly, the reduction in blood pressure occurred in both hypertensive and normotensive subjects.
This study suggests that statins may be beneficial in reducing the risk of cardiovascular events in two ways - by reducing cholesterol and by reducing blood pressure. However, the beneficial effect of lowering blood pressure is only evident whilst medication is being taken - there is no residual effect after 2 months. This trial, though, only lasted 6 months therefore it is hard to say if residual effects would be apparent following a longer period of medication.