Cardiovascular risk factors in children could impair their cognitive function in adulthood, Finnish researchers have found, adding to the myriad ways childhood is known to be a critical period for influencing health outcomes later in life.
The study, published May 10 in Circulation, showed that high systolic blood pressure, total blood cholesterol and high body mass index in childhood were all individually linked to worse performance in learning and memory tests in middle age — and that having all three risk factors was associated with worse visual processing and decreased attention span, while having two risk factors was associated with worsened reaction time and movement time. "If a person had all three of these risk factors, then they were like 20 years older in cognitive aging compared with those with no risk factors," Juuso O. Hakala, a doctoral student at the University of Turku in Finland and the lead and corresponding author of the study, told The Academic Times. "So, it's a pretty major finding."
Previous research has associated risk factors such as high blood pressure in adulthood with cognitive impairments, but the new study breaks ground in showing that mental deterioration could be set in motion during childhood, Hakala said. "We know that these cardiovascular risk factors are associated with cognitive impairments in midlife and later in life," he explained. "What's new is that this study shows that these risk factors are associated with cognitive impairments since childhood. So, this is the first study to find these associations. I think this hasn't been seen before because there are no other cohort studies that have data since childhood."
The researchers extracted data from the The Cardiovascular Risk in Young Finns Study, a longitudinal study that has followed about 3,600 Finnish men and women since 1980, when they were 3 to 18 years old, with follow-up appointments every three to nine years. In 2011, more than 2,000 of the participants — then ranging from ages 33 to 50 — ran through a computerized cognitive test that measured episodic memory, or the direct recollection of everyday events, and associative learning, the linking of separate elements through conditioning; short-term working memory; reaction time and movement time; and visual processing and sustained attention.
"The cognitive tests were done on a tablet, with ordinary memory games like remembering correct pairs," Hakala said. "The visual processing test was remembering a sequence of three numbers. There was one spot on the tablet screen where numbers changed quite quickly and the person had to push a button if they saw a sequence of three numbers they had seen before. Every time they saw this sequence, they had to push the button. So, they had to concentrate very strictly."
Drawing data points across time from the longitudinal study bolsters the findings, he said: "The cognitive test was performed after 30 years, so it's quite unique. The data has been collected several times, so that gives us an opportunity to create cardiovascular risk factor profiles so we can put out longitudinal associations, a unique way to look at things."
Yet the results are limited in that the cognitive performance of adults in the Young Finns study was measured just once, providing the researchers with no baseline data, though they compensated for this in their statistical models by incorporating school performance and socio-economic variables, such as family income, as proxies for cognitive performance.
The authors suggest that it's important to identify risk factors for cognitive decline and take preventative action — cardiorespiratory fitness, for example, has been shown to keep brains sharp into older ages — as early as possible, noting that many major causes of dementia have no cure. "I think we have to identify these persons who are at high risk because there is a clinical phase where you don't have any symptoms of cognitive diseases," Hakala said. "For example, in Alzheimer's disease, this [clinical phase] might last decades. That's why we have to concentrate on [early intervention] and catch these causes for cognitive decline."
Hakala believes the findings also highlight that it's critical to instill good exercise and dietary habits in early childhood and well into maturity: "It's important to adopt these good lifestyle [habits] in childhood and carry them into adulthood and later life. It's never too late to start influencing these cardiovascular risk factors, but since we know these associations come in childhood, it's very important to move the focus onto primary and preventative medicine."
A follow-up study is already in the works, Hakala said. The cognitive performance of the participants in the Young Finns study was recently measured for a second time, as was the cognitive performance of their children — providing researchers with cross-generational, epigenetic data that may further illuminate the connection between early heart health and cognitive decline in adulthood.
The study, "Cardiovascular risk factor trajectories since childhood and cognitive performance in midlife," published May 10 in Circulation, was authored by Juuso O. Hakala, Katja Pahkala, Pia Salo, Olli T. Raitakari and Suvi P. Rovio, Research Centre of Applied and Preventive Cardiovascular Medicine and University of Turku; Markus Juonala and Jorma S.A. Viikari, University of Turku; Mika Kähönen and Nina Hutri-Kähönen, Tampere University; Terho Lehtimäki, Tampere University and Fimlab Laboratories and Finnish Cardiovascular Research Center; Tomi P. Laitinen, University of Eastern Finland and Kuopio University Hospital; Eero Jokinen, University of Helsinki; Leena Taittonen, Vaasa Central Hospital and University of Oulu; Päivi Tossavainen, University of Oulu.