Conclusion These results show that self reported engagement is not associated with the trajectory of cognitive decline in late life, but is associated with the acquisition of ability during the life course. Overall, findings suggest that high performing adults engage and those that engage more being protected from relative decline. 
 
 Results Intellectual engagement was significantly associated with level of cognitive performance in later life, with each point on a 24 point scale accounting for 0.97 standardised cognitive performance (IQ-like) score, for processing speed and 0.71 points for memory (both P<0.05). Engagement in problem solving activities had the largest association with life course cognitive gains, with each point accounting for 0.43 standardised cognitive performance score, for processing speed and 0.36 points for memory (both P<0.05). However, engagement did not influence the trajectory of age related decline in cognitive performance. Engagement in intellectual stimulating activities was associated with early life ability, with correlations between engagement and childhood ability and education being 0.35 and 0.22, respectively (both P<0.01). 
 
 Introduction 
 
 Loss of mental competence can cause substantial anticipatory concern among older adults (that is, age> 65 years) by suggesting that such loss heralds the onset of progressive cognitive decline and dementia.1 Public health guidance on successful ageing highlights the importance of social and physical activity and engagement.2 Cognitive endeavours that engage multiple activity domains might have important benefits.3 However, longitudinal analysis of potential protective effects of cognitively effortful pursuits is difficult and a variety of methodological challenges have been documented. In studies4 that track cognitive change in adulthood, there are a dearth of historical data on childhood mental ability and limited awareness that early performances on IQ-type tests are already confounded by reading proficiency acquired before IQ-type scores can be obtained. 
 
 Another concern is the potential practice effects that can result from exposure to a common test format, and the possibility that differences in initial cognitive ability influence the size of practice effects observed.5 Results presented by Wesnes and Pincock in 20026 suggest that improvements in practice effects for commonly used tests of processing speed and memory are largest between the first and second occasion, with little improvement after that. Modelling of longitudinal data allows such practice effects to be accounted for by an initial practice model.7 Finally, reports of the effects of additional common confounders such as education and sex on cognitive performance are mixed, but it is generally accepted that education and sex affect cognitive performance in particular domains8 and early education has an influence across the life course.9 
 
 Activity engagement is so often argued to be an important dimension of successful ageing10 (and more specifically, the preservation of intellectual function in old age11121314151617) that the “use it or lose it” conjecture already appears to be an established fact of cognitive ageing. We aimed to re-examine this claim by analysing the effects of activity engagement on cognitive test performance and the trajectory of that performance in late adulthood. In addition, we aimed to test the robustness of observations by controlling for life course cognition and education. 
 
 Various studies support the “use it or lose it” conjecture. For example, Stanovich and colleagues proposed in 1995 that literary habits and exposure to print might be one way in which cognitive capacities are maintained with age.18 In their cross sectional study including a sample of younger and older adults, the researchers found that measures of exposure to print was associated with the positive relations between age and vocabulary, and between age and declarative knowledge. In 1997, Christensen and colleagues assessed the influence of self reported and informant reported activity levels on crystallised intelligence, fluid intelligence, memory, and mini-mental state examination scores in a sample of community dwelling, older participants. They found that specific activities were associated with higher cognitive performance in less well educated participants, but had no effect on cognitive performance in highly educated participants.12 In 2003, Verghese and colleagues conducted a prospective cohort study of older adults who resided in the community and did not have dementia at baseline.17 They reported that even after statistically controlling for educational level, presence or absence of chronic medical illnesses, and baseline cognitive status, those individuals who participated at least twice weekly in cognitive activities such as reading, playing board games, and playing musical instruments had significantly reduced risks for dementia.13 
 
 Our collaborators, who studied survivors sampled from the Scottish Mental Surveys, have also examined possible links between activity engagement and cognitive functioning in later life. Their study identified typical intellectual engagement scores (recorded on a self report questionnaire) and childhood mental ability as powerful effects on verbal fluency scores in late life.19 The evidence is clear that there is an association between typical intellectual engagement and cognitive ability in late life, although data on the longitudinal trajectory of cognitive change are sparse. However, the strength of any association between engagement and cognition is unclear, and it may well be that both cognition and engagement share a common origin (eg, early ability or education). 
 
 With access to archives of childhood mental ability and repeated measurement of cognitive ability in late adulthood, we aimed to investigate the possible effects of childhood ability, education, sex, and practice as a result of repeated cognitive testing when investigating the influence of typical intellectual engagement on late life cognition and the trajectory of decline. We analysed trajectories for two cognitive tests used repeatedly on our study group: the auditory verbal learning test as an indicator of memory performance, and the digit symbol substitution test as a measure of mental speed. Both tests are known to be sensitive to the effects of ageing and are measures of fluid ability.20 ||||| Image copyright Getty Images 
 
 Doing crossword puzzles and Sudoku does not appear to protect against mental decline, according to a new study. 
 
 The idea of "use it or lose it" when it comes to our brains in later life has previously been widely accepted. 
 
 The new Scottish study showed that people who regularly do intellectual activities throughout life have higher mental abilities. 
 
 This provides a "higher cognitive point" from which to decline, say the researchers. 
 
 But the study did not show that they decline any slower. 
 
 The work, published in the BMJ, was undertaken by Dr Roger Staff at Aberdeen Royal Infirmary and the University of Aberdeen. 
 
 It looked at 498 people born in 1936 who had taken part in a group intelligence test at the age of 11. 
 
 This current study started when they were about 64 years old and they were recalled for memory and mental-processing-speed testing up to five times over a 15-year period. 
 
 It found engagement in problem solving did not protect an individual from decline. 
 
 However, engaging in intellectually stimulating activities on a regular basis was linked to level of mental ability in old age. 
 
 Proof? 
 
 The study uses modelling to look at associations and cannot prove any causal link. Also, many of the participants were unable to complete the whole study - some dropped out, others died. 
 
 Image copyright Getty Images 
 
 Previously, some studies have found that cognitive training can improve some aspects of memory and thinking, particularly for people who are middle-aged or older. 
 
 They found so-called brain training may help older people to manage their daily tasks better. 
 
 No studies have shown that brain training prevents dementia. 
 
 And last year a report from the Global Council on Brain Health recommended that people should take part in stimulating activities such as learning a musical instrument, designing a quilt or gardening rather than brain training to help their brain function in later life. 
 
 It said the younger a person started these activities, the better their brain function would be as they aged. 
 
 Dr Staff and colleagues say even though their study did not find puzzles counteracted mental decline, it doesn't mean they are a waste of time. 
 
 Dr David Reynolds, chief scientific officer at Alzheimer's Research UK, said the research added to the "ongoing 'use it or lose it' debate". 
 
 But as the research did not consider people with dementia, "we can't say from these results whether specific brain training activities could impact a person's risk of the condition". 
 
 "In addition to staying mentally active, keeping physically fit, eating a healthy balanced diet, not smoking, drinking within recommended guidelines and keeping weight, cholesterol and blood pressure in check are all good ways to support a healthy brain as we get older." 
 
 Dr James Pickett, Head of Research at Alzheimer's Society, said: "Although playing 'brain games' such as Sudoku may not prevent dementia, is has been shown that regularly challenging yourself mentally seems to build up the brain's ability to cope with disease."
– Scottish researchers have some good news and bad news for those who do crosswords, Suduko, and similar puzzles. Such brain-training exercises will not prevent mental decline or ward off dementia, suggests their new study in the British Medical Journal. However, the researchers do see a benefit for puzzlers, making a subtle distinction in what they call the "use it or lose it" debate: Doing puzzles regularly throughout life seems to result in people having a "higher cognitive point from which to decline." The puzzlers just shouldn't expect the decline to be any slower once it begins, reports the BBC. The study looked at nearly 500 people born in 1936 who first took an intelligence test at age 11 and have participated in followup tests over the years, per the Aberdeen Evening Express. The researchers note that theirs is an observational study, not one that proves cause and effect. And as for the common practice of working puzzles into cognitive training programs for seniors, well, they can't hurt—"the intentions appear laudable with no apparent ill effects." They also note that the holidays are coming up, and they don't want their study to ruin any gifts such as a big Sudoko book or chess board. "If family and friends give you a disappointed look on opening their Christmas present, remind them that investment in intellectual activities throughout life could provide them with a higher cognitive point from which to decline," they advise. "Surely, this is as good a gift as any!" (Changes in your speech could offer a clue into mental decline.)