Dr Gareth Moore (B.Sc (Hons) M.Phil Ph.D) is the internationally bestselling author of a wide range of brain-training and puzzle books for both children and adults, including Anti-stress Puzzles, Ultimate Dot to Dot, Brain Games for Clever Kids?, Lateral Logic, Extreme Mazes and The Ordinance Survey Puzzle Book. His books have sold over a million copies in the UK alone and have sold in 35 different languages. He is also the creator of online brain-training site BrainedUp.com and runs the daily puzzle site PuzzleMix.com. Helena M. Gellersen is a doctoral researcher in the Memory Laboratory at the University of Cambridge. Her work centres around long-term memory and brain changes in healthy ageing and the early stages of dementia. Her research has been featured in multiple peer-reviewed journals, podcasts and blogs.