There are two well-known problems with "standardized" neuropsychological testing:
- Although it is supposed to be objective, the results are often strongly affected by the subjective bias of the examiner.
- Because of individual differences in "intelligence" or innate cognitive ability, the results of testing must be compared to the pre-illness results from the same individual in order to determine any reduction in function. Comparison to a population average is often misleading.
These were exactly the two issues I encountered. The psychologist I saw believed I was depressed, and this colored every aspect of his report. As a result his conclusions glossed over what I thought were relevant findings--in tests of attention, concentration, recall, and working memory I consistently scored below average, as low as the 25th percentile--and instead emphasized his perception of my psychological state.
When I showed the report to my doctor, she just glanced at my overall score and said: "Well, your scores are above average, so there doesn't seem to be any problem!" Plus, since I hadn't had neuropsych testing since I was 10 years old (my neighbor was a psychologist and I ended up in the control group of one of her studies), there was no way to compare apples to apples and prove that my scores really reflected diminished function, nor could they show by how much my abilities had slipped.
Putting on my special education hat, if you do have neuropsych testing it's important to know that the overall scores aren't really helpful (unless you're trying to get into Mensa). What's more helpful is to glance over all of the subtest scores, usually on the last page of the report, and take note of any scores which seem unusually high or low in comparison with the others. In my report most of my scores are clustered around a certain range, but tests of memory and concentration stand out because they are generally over a standard deviation lower than the rest.