In a number of past legal updates, the effect of multiple forces such as pain, life stress and specific psychiatric problems upon neuropsychological testing and every day functioning were mentioned. Perhaps no single issue has raised as many questions nor as much diversity of finding in the research literature as the role depression may play on an individual’s perception of their cognitive abilities and every day functioning, as well as serving as a modifying variable in reducing capability as measured by laboratory based neuropsychological test instruments. A recent well-controlled study appearing in the Archives of Clinical Neuropsychology (Volume 17, 2002, pages 205-222) addressed this issue. The findings are interesting and particularly relevant in the forensic arena. This legal update will briefly review the issue of depression, every day functioning and neuropsychological testing as well as summarize the findings of this study.
There has been considerable research in the past forty years on the impact of major depression on neuropsychological functioning. Research findings have varied significantly with issues raised concerning researchers’ ability to control for confounding differences between control and experimental groups. Issues such as age, education, comorbid psychiatric problems, life history or medications have all been questioned as possibly responsible for many of the differences found between studies. In fact, a number of researchers have reported that there is lack of a coherent theory to explain any true impact depression might have on memory function. Further, the majority of these studies have not examined individuals with neurological problems, particularly those experiencing problems secondary to brain injury or for that matter involved in litigation. Yet, this has become a critical issue when neuropsychologists are asked to determine whether a patient’s daily complaints about memory or cognitive inefficiency are the result of psychiatric condition, trauma, pre-morbid status or a combination. It is still not uncommon in the forensic neuropsychological literature for clinicians to ascribe inconsistencies in laboratory test performance to a psychiatric rather than organic basis.
Martin Rohling and colleagues examined a population of 420 individuals with a two day comprehensive neuropsychological evaluation completed as part of compensation disability claims. Half of the individuals were referred as the result of actual or alleged head injuries, 20% for depression, 10% for other neurological problems, 5% with chronic fatigue syndrome, 4% with orthopedic injuries, 4% with chronic pain and 6% with miscellaneous other diagnoses. The assessment typically took approximately eight hours of face to face evaluation. Patients were also administered multiple symptom validity (malingering) tests. Any individual failing these tests was excluded from the study. The authors’ rationale was that individuals who fail symptom validity tests either intentionally perform poorly, produce invalid results to obtain compensation or produce invalid results for some other reason. The authors suggest that if these individuals had been included in the analysis, it would be unclear whether their deficits were due to depression, intentionally poor performance or disengagement from the testing process. The authors also chose control participants from the same sample of clinical patients as the depressed participants. Control patients were well matched to depressed individuals regarding age, education and verbal intelligence.
The results were extremely interesting and inconsistent with a number of previous research studies. Insignificant correlations between measures of depression and various clusters of neurocognitive testing were found. No significant relationships were found between objective performance and severity of depression either. Interestingly, however, patients with high symptoms of depression reported significantly more daily problems with memory than did patients who were in the low depression symptom group. However, when memory complaints were compared to actual performance, no relationship was revealed. Self-perceptions of memory functioning bore little relation to objective performance.
In light of these data, it should be expected that the more severe an individual’s depression, the more likely he or she will complain of daily, impaired functioning related to memory and general cognitive efficiency. However, these data suggest that such complaints should not be accepted as valid except as an indicator of subjective perception. A complaint of cognitive dysfunction should not be assumed synonymous with the presence of a deficit or significant impairment.
Multiple diagnoses, particularly those related to chronic pain and psychiatric problems such as depression, anxiety and post traumatic stress disorder, occur with great frequency in individuals presenting with neurologic conditions, even those with a history of mild head trauma. These data suggest that a neuropsychologist should be very careful when determining that an individual’s poor performance on a well-controlled, laboratory neuropsychological measure is simply due to depression or other psychiatric conditions. Thus, depression is associated with complaints of poor memory but appears to have little effect on objective measures of neurocognition or psychomotor performance. When a depressed individual obtains low scores on ability tests, this may not be because the individual is depressed. The reason for such impaired scores should be carefully evaluated beyond the individual’s psychiatric status. In some cases this may be the unfortunate result of trauma while in others it may simply reflect the individual’s pre-trauma status.