Sir Arthur Conan Doyle, the creator of Sherlock Holmes, compared the human brain to an empty attic, with one catch: ‘You have to stock it with such furniture as you choose.’

Neuroscientists may dispute the ‘empty’ side of things—a living brain might seem inert to the naked eye but it’s never empty. No clinician worth their salt, however, would quibble that ours is the power to furnish the room upstairs, equipping the brain with fresh ways of thinking—the idea central to this book. Whether you load your cranium with detective novels or music, maps or Grand Prix races, the input will influence how you see the world, and how your brain operates.

Puzzles alone can shape your grey matter in surprising ways. A simple matchstick array, for instance, can sharpen your spatial smarts. A sudoku grid is tailor-made to hone your logic, pushing the bounds of what-if algebra well past the grid’s confines. Anagrams can blend your powers of language dexterity and problem-solving as much as blending letters. And then there are the lateral leaps involved in a cryptic crossword, furnishing the attic with fittings you’ve never even imagined.

All these pursuits occupy Part One of Rewording the Brain, as we grapple with the why behind the puzzle impulse: why our brains are attracted to wordplay and other deceptions in the first place, and why the habit of solving conundrums has multiple benefits for Doyle’s room upstairs.

Part One will also reveal how an appetite for puns can encourage an inventive mindset. We’ll take time to road-test quick and cautious thinking, seeing how puzzles can boost both modes, and why they enhance daily resolutions. We’ll also explore how cryptic language boosts the knack of connecting and disconnecting concepts both small and large: one more avenue towards a lither brain.

More than memory or focus or strategic savvy, puzzles can deliver subtle advantages. To understand these in real terms, we’ll call on the latest studies from home and abroad, playing jazz and obsessing over blackberries, visiting an amnesiac called HM plus a lovable crossword class, unlocking research that maps the way we humans have flourished as insightful animals.

Flourished and endured—with census data indicating some 15 per cent of Australians are now over 65, a portion translating as close to four million people. Projections suggest that figure will reach 8.7 million by 2056. Yet growing older doesn’t always mean growing better; brains age in tandem with their owners. The cortex—or outer layer—thins. Plasticity abates. Neural links can slow over time. And the older we get, the more we live with the spectre of dementia.

But we can make an active difference and lend our brains every chance to keep pace with an evolving world. How might puzzles—and other brain games—help us? Can a crossword a day really keep the fog at bay? Part One aims to illuminate what the latest findings tell us.

Over the next ten chapters we’ll enter the brain itself, starting with a virtual tour. Or at least, we will as much as anybody can: even among experts, like British neuroscientist Susan Greenfield, the brain remains ‘the final frontier in human understanding’. In a space the size of a match-head, say, the brain plays host to as many as a billion neural connections, teeming with activity. In a short while we’ll learn the nature of this tumult and how we might enhance its powers via puzzling.

No sooner will you learn of the brain’s floorplan and functions—the secrets behind deduction and intuition—than you’ll reach a second mystery, better known as cryptic crosswords. Gobbledegook to some people, addictive delight to others, the cryptic clue in all its shapes and sizes will be unravelled in Part Two, the book’s other hemisphere if you like, the How-To succeeding the Why. There I’ll equip you with the art of clue-conquering, sharing the lowdown on the cryptic genre’s formulas—from anagrams to charades, from homophones to reversals—telling you how to spot them and how to pounce.

That said, you may already be a seasoned solver. If so, feel free to leapfrog Part Two, although I’d advise otherwise, since tucked away in this segment is a celebration of the craft’s finer points, outlining the rarer traps you may meet in the land of Cryptopia. Rookies and veterans alike will glean insights galore, and meet some spectacular clues as examples.

After the tutorial comes the party that embodies Part Three: a suite of 50 puzzles to extend your brand-new talents. Part Three—the cerebellum annexed to the book’s two hemispheres—is an original crossword collection arranged from friendly to gnarly. First come the samplers, mini-grids devoted to certain cryptic recipes, and later a procession of mixed clues, with sneak-peek options to reveal each clue type in case the going gets too tough.

Beyond that, in the coda of puzzles to conclude the book, you’ll be solving solo. Maybe you won’t crest the highest peak this time around, but you’ll definitely learn the reasons why the striving counts, as well as grow familiar with the ground rules. Regardless of the heights you climb, your grey matter will thank you, not just today, but every day you wrestle with a puzzle. Rewording the Brain is the book to explain why, as well as show you how.