My father is taking part in a study of older adults with chronic low back pain. We’re noticing he’s having significantly less pain now that his mental abilities are starting to slip. Should we notify the people running the study? It seems that something like this could really skew their results.

You ask a very good question. Many times, studies are set up with inclusion and exclusion criteria. This means that the subjects included must have certain characteristics to be included. And if they have others, they are excluded. Cognitive impairment and mental function is often on the list of exclusion criteria.

Many studies of older adults include tests to measure mental function and mood. The researchers may use the results to exclude subjects who aren’t appropriate for the study. In other cases, the results of such tests are an important part of the study.

For example, a recent study on the impact of low back pain on older adults was done. They found that depression had a major impact on disability. Decreased function from chronic pain leads to a decline in quality of life. Depression may naturally follow.

You can certainly discuss your concerns with the people running the study. But you may find that your father will still remain part of the study. They may be looking for people just like your father as part of the study. If not, statistical analysis will take care to explain skewed results from subjects who are outside the norm.