Leisure Activities and Dementia. An article appearing in the Los Angeles Timesdiscussed the study " Leisure Activities and the Risk of Dementia in the Elderly "(New England Journal of Medicine, Vol. 348, pp . 2508-2516 ) by J. Verghese et al. The article in the Times, titled "Crosswords Reduce Risk of Dementia," contained the following statement: " Elderly people who frequently read, do crossword puzzles, practice a musical instrument or play board games cut their risk of Alzheimer's and other forms of dementia by nearly two-thirds compared with people who seldom do such activities." Comment on the statement in quotes, keeping in mind the type of study for which causation can be reasonably inferred.

The given statement says that when compared to persons who rarely read, do crossword puzzles, practice a musical instrument, or play board games, elderly people who do so frequently cut their risk of Alzheimer's and other kinds of dementia by approximately two-thirds.

According to the above-said article, when compared to persons who rarely perform such activities, elderly people who read, do crossword puzzles, practice a musical instrument, or play board games had a roughly two-thirds lower risk of Alzheimer's disease and other kinds of dementia.

In this case, the individuals were not assigned to one of the three groups at random.

To put it another way, the given study is not a controlled experiment.

Furthermore, it is evident that the studies look to see if the respondents participate in any of the activities so that the effect of dementia can be observed.

As a result, the provided study is clearly an observational study and it does not involve any cause-and-effect relationship.