Lifetime Risk Factors, Lifestyle, and Vascular Health in Adulthood

Abstract

Elinaikaiset riskitekijät, elintavat ja aikuisiän valtimoterveys

Tarkastettava väitöskirjatyö tutki lapsuudessa ja aikuisiällä määritettyjen valtimotaudin riskitekijöiden, kuten verenpaineen, verensokerin, veren kolesterolin, tupakoinnin, liikunnan ja ruokavalion, yhteyttä aikuisiän pulssiaallon etenemisnopeuteen. Pulssiaallon etenemisnopeutta voidaan pitää valtimoiden ikääntymisen mittarina. Se ennustaa itsenäisesti sydän- ja verisuonisairauksien päätetapahtumia, kuten aivohalvausta, sydäninfarktia ja sydänperäistä kuolemaa.

Tutkimuksen tulokset osoittivat, että sekä lapsuuden että aikuisiän systolinen verenpaine ennustaa itsenäisesti aikuisiän pulssiaallon etenemisnopeutta. Lapsena paljon hedelmiä ja vihanneksia syöneillä oli aikuisiällä matalampi pulssiaallon etenemisnopeus kuin niitä vähän syöneillä. Vaikutus oli vielä merkittävämpi, jos hedelmien ja vihannesten käyttö oli runsasta lapsuudesta aikuisikään. Suotuisat riskiprofiilin muutokset, sekä lapsuudesta aikuisikään että nuoresta aikuisiästä keski-ikään, olivat yhteydessä matalampaan pulssiaallon etenemisnopeuteen ja siten alhaisempaan valtimoiden jäykkyyteen aikuisiällä. Tämä muutos säilyi merkitsevänä, kun huomioitiin lähtötilanteen riskiprofiili.

Tämän tutkimuksen tulokset kannustavat vähentämään valtimotaudin riskitekijöitä ja mikäli mahdollista, jopa estämään niiden kehittymistä. Pulssiaallon etenemisnopeuden mittaamisesta voisi olla hyötyä kliinisessä työssä sydän- ja verisuonisairauksien hoidossa ja riskiarviossa.

Background: Our understanding of the pathophysiology of atherosclerosis has expanded considerably during last two decades. A multifactorial pathophysiological process describes the progression at molecular and cellular levels, eventually manifesting itself as clinical disease. All these processes already begin in childhood, but clinical manifestations—e.g. coronary heart disease, myocardial infarction, or stroke—usually occur decades later in middle-age or in old age. Several reports have consistently shown the favorable effects of lifestyle changes. To improve primordial prevention, i.e. to prevent the development of risk factors, the American Heart Association released in 2010 the concept of Ideal Cardiovascular Health: the simultaneous presence of 4 ideal health behaviors (non-smoking, normal body mass index, being physically active, and a healthy diet) and 3 ideal health factors (normal total cholesterol, blood pressure, and fasting glucose). The health-promoting benefits of each of the components have been well established. This concept has been shown to predict lower cardiovascular disease risk and mortality of all causes. However, the prevalence of Ideal Cardiovascular Health has been extremely low in adolescence and in adulthood. Simultaneously with the atherosclerotic process, aging causes stiffening of elastic arteries, and especially of the aorta. When the aorta ages and stiffens, the pulsations created by the left ventricle cannot be cushioned and are transmitted into the capillaries especially in the brain and kidneys, causing microvascular damage. Arterial aging also increases pressure throughout the systole, which leads to left ventricle hypertrophy and an acceleration of the atherosclerotic process. Arterial aging is an independent process which could advance without atherosclerosis. It is not possible to study only the process of atherosclerosis without arterial stiffening, because it is difficult to separate age-related changes from disease-related changes. Arterial stiffness could be assessed by measuring pulse wave velocity, which is accepted as an independent predictor of cardiovascular events and as a biomarker of vascular aging.

Aims: The present study elucidates the associations of traditional and lifestyle risk factors measured in childhood and adulthood with pulse wave velocity assessed in adulthood. Risk factors were used as continuous variables and as defined in the concept of Ideal Cardiovascular Health. Additionally, the present study investigated the association between the change in Ideal Cardiovascular Health status (both from childhood to adulthood and from young adulthood to middle age) and pulse wave velocity in adulthood. Moreover, blood pressure in childhood was defined as normal or elevated according to the three different definitions to investigate whether elevated pediatric blood pressure could predict high pulse wave velocity in adulthood and whether there is a difference in predictive ability between the different definitions.

Subjects and Methods: The population studied in this thesis is from the Cardiovascular Risk in Young Finns Study. The first cross-sectional study was conducted in 1980, and 3,596 subjects aged 3−18 years attended. Follow-up studies with standard physical examinations and blood samplings were conducted in 1983, 1986, 2001, and 2007. Pulse wave velocity measurements by impedance cardiography were carried out in 2007, with 1,872 (52.1% of original cohort) participants (aged 30−45 years) attending.

Results: Systolic blood pressure and glucose in childhood, and systolic blood pressure, insulin, and triglycerides in adulthood were independent predictors of adult pulse wave velocity. Vegetable consumption both in childhood and in adulthood was inversely and independently associated with adult pulse wave velocity, and the association remained significant when adjusted for lifestyle or traditional risk factors. Elevated pediatric blood pressure predicted high adult pulse wave velocity, and the predictions were equivalent for the simplified and complex definitions. The change in the ideal cardiovascular health index was inversely related to pulse wave velocity in adulthood. This relationship was significant for the younger (change from childhood to adulthood) and the older (change from young adulthood to middle-age) participants and remained significant after adjusting for the ideal cardiovascular health index at baseline.

Conclusions: Traditional and lifestyle risk factors in childhood and adulthood predict pulse wave velocity in adulthood. Favorable changes in risk factor status, both from childhood to adulthood and from young adulthood to middle-age, are associated with lower pulse wave velocity in adulthood. Elevated blood pressure is a major risk factor and the simplified blood pressure tables could be used to identify children at an increased risk of high arterial stiffness in adulthood. These results support the efforts to reduce risk factors both in childhood and adulthood in the primary prevention of atherosclerosis.