ADT and changes in cognitive performance

A new — but very small and short-term study — has attempted to assess the baseline prevalence of cognitive impairment in older men treated with androgen deprivation therapy (ADT) and changes in cognitive performance over time.

This study by Mohile et al. was set up to carry out an intensive analysis of cognitive function in 32 patients immediately before they started ADT and then again after 6 months. Here are the critical aspects of the actual study design:

  • The patients had a median age of 71 years  with a range of between 51 and 87 years), which is a wide age range in a small patient group.
  • All patients were given an extensive neuropsychological battery of tests prior to ADT initiation.
  • Only 21/32 patients (65 percent) completed post-treatment evaluations 6 months later.

What this means is that we are actually looking at possibly meaningful data from only 21 patients over just 6 months, and since many patients only start to report significant effects of ADT on cognitive function after a year or more on therapy, we have to interpret these results with very great caution.

Having said that, here are the results that Mohile et al. report:

  • At baseline, 14/32 patients (45 percent) scored >1.5 standard deviations below the average on at least 2 neuropsychological measures. (This is hardly a surprise: about half the patients had a lower than average result — implying that about half also had an above average result!)
  • There was no apparent change in cognition in the 21 patients for whom data were available following treatment. (In addition, this was also true specifically for the patients who scored below average on cognitive function prior to therapy.)
  • 38 percent of patients demonstrated a decline in measures of executive functioning and 48 percent showed improvement on measures of visuospatial abilities. (We assume that these percentages are based on the 21 patients who completed follow-up tests and not on the 32 patients who entered the study. In other words, we are talking about resulst based on 8/21 and 10/21 patients respectively.)
  • Patients with average or better scores at baseline displayed improvements in two areas: visuospatial planning and timed tests of phonemic fluency.

The authors conclude their abstract by stating that they “found a high prevalence of lower than expected cognitive performance among a sample of patients just starting ADT for prostate cancer. Assessment of baseline cognitive function should be taken into account for future research and to inform clinical management.”

Frankly, we don’t understand the authors’ first conclusion. If 45 percent of patients in any trial are below the mean, then 55 percent are above the mean, and this is not even close to surprising.

With respect to their second comment, in our opinion, before we start drawing conclusions about the measurable impact of ADT on prostate cancer patients, we think it would be necessary to do much larger studies, in which patients were carefully stratified by such things as age, educational achievement, income, etc., and were then tested regularly, every 6 months, over a period of not less than 2-3 years, which would give us a much more meaningful assessment of the real impact of hormone therapy on patient quality of cognitive performance.

One Response

  1. Not much to reply, other than I agree with your assessment. Insufficiently comprehensive data.

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