At first read, the study results seemed disappointing. Yet another promising premise fails to deliver when it comes to actual proof. But the researchers aren’t ready to give up on this hypothesis just yet. In fact, commentators on the study say the results offer ‘great hope’ and represent ‘a major leap forward.’ The SPRINT MIND study, recently published in JAMA was investigating whether intensive blood pressure control (to a systolic less than 120mmHg) worked better than standard blood pressure control (SBP<140mmHg) at reducing the risk of mild cognitive impairment and dementia. This randomised controlled trial was a component of the well-publicised Systolic Blood Pressure Intervention Trial (SPRINT) which looked at the effect of more intensive blood pressure control on cardiovascular and renal outcomes in addition to cognitive function in over 9000 people without a history of diabetes or stroke. Basically, what this study showed was that intensive blood pressure control to a target of less than 120mmHg did not reduce the incidence of probable dementia compared to lowering BP to a target of less than 140mmHg. Depressing, yes? No, say the study authors. Firstly, they say the study demonstrated no ill-effects of intensive BP lowering – which has been an issue of concern for some who have been worried that lowering the BP could decrease cerebral perfusion thereby harming cognitive function. In fact, the study authors showed quite the opposite was true. The intervention actually helped protect cognitive ability. “This is the first trial, to our knowledge, to demonstrate an intervention that significantly reduces the occurrence of [mild cognitive impairment], a well-established risk factor for dementia, as well as the combined occurrence of [mild cognitive impairment] or dementia,” they said. The study authors suggest the lack of benefit in dementia may be due to the fact the SPRINT study was terminated early following the demonstration of benefit of intensive BP control on cardiovascular outcomes and all-cause mortality. Because of this shortened time frame and the fact that there were fewer than expected cases of dementia, they suggest the study may have been ‘underpowered’ to show a result for lowering the risk of dementia. They also say there were fewer cases of dementia among the intensive treatment group compared with the standard treatment group (7.2 vs 8.6 cases per 1000 patient years) even though this wasn’t statistically significant. We cannot know whether this trend would have reached statistical significance had the intervention continued. An accompanying editorial views the study and the results with a good deal of positivity. “For older adults, almost all of who have concern about being diagnosed with Alzheimer Disease and related dementia, [this study] offers great hope,” the US epidemiologist, Dr Kristine Yaffe, said. She points out that this a readily modifiable risk factor, and we should be accelerating our efforts into investigating whether this, along with other vascular health interventions such as physical activity, can indeed prevent dementia, building on the positive results of this study. “The SPRINT MIND study may not be the final approach for prevention of Alzheimer disease or other cognitive impairment but it represents a major leap forward in what has emerged as a marathon journey.”

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Adolescent boys who struggle to understand how basic machines work and young girls who have difficulty remembering words are at increased risk of developing dementia when they’re older, new research has found. According to the longitudinal study published in The Journal of the American Medical Association, lower mechanical reasoning in adolescence in boys was associated with a 17% higher risk of having dementia when they were 70. With girls it was a lower memory for words in adolescence that increased the odds of developing the degenerative disease. It has been known for some time that the smarter you are throughout life, even as a child the less likely it is that you will develop dementia. Not a guarantee of protection – just a general trend. It has to do with cognitive reserve, the US researchers explain. “Based on the cognitive reserve hypothesis, high levels of cognitive functioning and reserve accumulated throughout the life course may protect against brain pathology and clinical manifestations of dementia,” they wrote. This theory has been supported by a number of studies such as the Scottish Mental Health Survey that showed that lower mental ability at age 11 increased the risk of dementia down the track. But what had been less well-defined was whether there were any particular aspects of intelligence in young people that were better predictors (or protectors) of dementia than others. This study goes some way to addressing this. Researchers were able to link sociobehavioural data collected from high school children back in 1960 with Medicare claims data over 50 years later that identified those people who had been diagnosed with Alzheimer's disease and related disorders. Interestingly, poor adolescent performance in other areas of intelligence such as mathematics and visualisation were also associated with dementia but not nearly to the extent of mechanical reasoning and word memory. So why is this so? The study authors say there are a few possible explanations. Maybe the poor performance in adolescence reflected poor brain development earlier in life, a risk factor for dementia. Or maybe these adolescents are more susceptible to neuropathology as they get older? Or maybe they are the adolescents who adopt poor health behaviours such as smoking and little exercise? “Regardless of mechanism, our findings emphasise that early-life risk stretches across the life course,” they said. And what can be done about it? That’s the million-dollar question. The researchers say the hope is if we know the at-risk group we can get aggressive with preventive management early. “Efforts to promote cognitive reserve-building experiences and positive health behaviours throughout the life course may prevent or delay clinical symptoms of Alzheimer's disease and related disorder.” An accompanying editorial takes this concept a little further. Dr Tom Russ, a Scottish psychiatrist says interventional research has identified a number of factors that can potentially influence cognitive reserve. These include modifiable health factors, education, social support, positive affect, stimulating activities and/or novel experiences, and cognitive training. As Dr Russ says, you can’t necessarily change all of these risk factors, and even the ones you can change may become less modifiable later in life. But as this study demonstrates, you may be able to work on a person’s cognitive reserve at different stages throughout their life to ultimately lower their risk of dementia.   Reference

1. Huang AR, Strombotne KL, Horner EM, Lapham SJ, Adolescent Cognitive Aptitudes and Later-in-Life Alzheimer Disease and Related Disorders. JAMA Network Open [Internet]. 2018 Sep; 1(5): e181726. Available from: https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2701735 doi:10.1001/jamanetworkopen.2018.1726.
2. Russ TC, Intelligence, Cognitive Reserve, and Dementia: Time for Intervention? JAMA Network Open [Internet]. 2018 Sep; 1(5): e181724. Available from: https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2701735 doi:10.1001/jamanetworkopen.2018.1724.