(CNN) Tackling a tricky crossword or a challenging Sudoku puzzle will not fend off age-related mental decline, new research has shown.

Scientists have, in recent years, argued that brain-training exercises, such as completing puzzles or learning another language, can reduce the risk of developing dementia. But that may not be the case after all, according to a team of Scottish researchers whose research was published in the BMJ

The study's authors argue that such pursuits will not necessarily act as a preventative, but they could still provide a "higher cognitive point" from which to decline.

The study considered 498 participants, all born in 1936 and who took a group intelligence test when they were 11 years old. Those records were kept by the Scottish Council for Research in Education. Then, at about 64 years old, they were tested for the current study and followed up with several more times for memory and mental processing over the next 15 years. The research was led by Roger Staff, honorary lecturer at the University of Aberdeen and head of medical physics at Aberdeen Royal Infirmary.

The researchers stressed that their work is an observational study, so it is "impossible for a causal effect to be inferred."

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