Should My Client Get Functional Neuroimaging?: The Forensic Neuropsychologist – Attorney Dialogue
Questions abound regarding the role of neuroimaging in the courtroom and its relationship to neuropsychological testing, behavioral disturbance, and day to day functioning. There have been recent advances in neuroimaging, resulting in functional neuroimaging methods such as SPECT, PET, QEEG, MEG, DTI, and fMRI. The attorney will ask the forensic neuropsychologist and other medical professionals about the necessity of these imaging methods in documenting residual after brain injury (e.g., “should my client get a PET scan?”). It is important to remember that these imaging methods are considered investigational for forensic purposes, particularly in the case of mild brain injury or concussion. Some of these technologies such as SPECT look at blood flow or metabolism in specific brain areas. When there is reduced blood flow, laypeople can mistakenly infer that this is evidence of compromise or less functionality in brain tissue (i.e., damage to brain tissue). However, this is not necessarily the case. This is because other factors such as metabolic issues, substance use, emotional disorders such as depression, obsessive compulsive disorder, anxiety disorders, and even schizophrenia can be reflected by abnormalities on SPECT technology. In the case of criminal cases, it is also the case that individuals who are neurologically normal and/or who have never faced allegations of criminal activity do demonstrate abnormalities on SPECT. The elusive 1:1 relationship between criminal behavior and brain functioning on imaging has yet to exist.
Further, neuropsychological test and evaluation findings do not necessarily bear a relationship to SPECT findings; that is, SPECT findings are not necessarily predictive of test findings. If neuropsychological test findings have been validated to predict day to day functioning and damage to brain tissue (for which strong evidence has been demonstrated), then what does this say about SPECT if SPECT is uncorrelated with test findings?
A review of the literature suggests that functional neuroimaging methods such as those listed above are not to be used in routine clinical care, yet questions about the use of this technology is arising more frequently in forensic/court settings.
One of the interesting questions arising is whether individuals with frontal lobe dysfunction and aggression exhibit behavior that is explained by imaging abonormalities as shown on PET scans (i.e., prefrontal hypoactivity). However, prefrontal hypoactivity can be experimentally induced by telling subjects to behave in an aggressive fashion. It is important for courts to bear in mind that questions of sanity and competency should be based on factors other than particular brain abnormalities on functional neuroimaging or a single test. These questions should be answered through a multi-factorial analysis which integrates the person’s presentation, history, cognitive and behavioral capacity, including psychiatric diagnosis, in addition to neuroimaging results. There will hopefully come a time when neuroimaging methods can be further developed to have the same predictive value that neuropsychological tests do now. The interest in neuroimaging on the parts of courts and juries is exciting but should be tempered with an understanding of the limits of these technologies. Rather, at this point, the preponderance of scientific evidence supports neuropsychological tests as predictors of cognitive and behavioral disturbance.
Disclaimer: No attorney-client or doctor-patient relationship is implied in the writing of this blog entry.