One doctor from a hospital in RI has said working crossword is just as effective as the commercial and formal brain training that has become popular in recent years. Crosswords have also been used in children to improve language and thinking skills and to improve spelling, vocabulary, grammar skills, and even comprehension.

A 21 year seniors study in the U. S. showed seniors who did crossword puzzles four days a week have a lower risk of dementia than those who did crosswords once a week. By doing crosswords, seniors can develop their:
memory
attention
language
problem solving
remembering peoples names
remembering simple tasks

Although the normal games like chess, crossword puzzles and other word games, bingo, etc. help exercise your brain, watching TV does not. The brain apparently is in neutral when watching TV shows. My guess is that this is because it is a passive activity that requires very little effort. An analogy could be made with muscle exercise for couch potatoes. If you don't do the exercise, mental or physical, you really aren't helping you.

If crossword puzzle solvers improve their brain functioning, the same should be true for people who solve other word puzzles requiring using the brain. Personal experience with both has convinced me that cryptograms require even more mental effort than doing crosswords. I enjoy doing both, but consider most cryptograms more challenging. Solving crosswords requires knowledge of words, but solving cryptograms involves not only knowledge of words, but word patterns, sentence structure and patterns, famous people in almost any field, rules of grammar, and loads of patience. Once you get hooked on cryptograms you may find yourself addicted, but unlike other addictions, this addiction pays you back. Your vocabulary as well as general knowledge will increase with every new cryptogram solving session.