Quantifying The Cognitive Aspects Of Mental Illness In The Forensic Patient By: Lawson F. Bernstein, M.D.
Email: lawsonbernstein@lfbmdpc.com
Website: http://www.lfbmdpc.comThis section will discuss those neurophysiological (e.g.-physical tests) and neuropsychological measurements that are often used by mental health professionals to assess and measure an individual's overall cognitive function, particularly in the realm of the capacity to form specific criminal intent.
An Overview of Functional Neuroanatomy
The brain is divided into two specific anatomic regions, the cortex and the brain stem. While the brain stem can be important in regards to behavioral and cognitive abnormalities, this section will concentrate on the role of the cortex in cognition. The cortex is divided into four regions: the frontal lobes, the temporal lobes, the occipital lobe, and the parietal lobes. The frontal and temporal lobes of the brain are involved in (amongst other cognitive functions) premeditation, deliberation, and the formation of specific intent (both as regards critical and non-critical decision-making). Specific abnormalities of these brain regions can result in cognitive abnormalities that may be important to a psychiatric defense. There are a variety of ways to assess frontotemporal cortical brain functioning, and these are discussed below.
In addition, many medical conditions (e.g. brain injury, seizure disorder, cancer, dementia, etc.) can be associated with specific abnormalities of the frontal and/or temporal lobes. When assessing your client for psychiatric disease, it is important to have an expert screen for pre-existing neurologic disorders, which may affect frontal or temporal lobe functioning.
The Limitations of DSM IV in the Forensic Setting
While the DSM-IV is a nosological document that seeks to categorize and subdivide mental illness by common characteristics, the forensic aspects of mental illness are in fact dimensional characterizations of cognition (at it's essence, cognition is defined as an individual's ability to think logically). Thus the legal definitions of an abnormal cognitive state do not correlate to any particular DSM IV diagnosis. That is to say that the law is often interested in cognitive concepts such as "insanity", "diminished capacity", and the like; which are really descriptions of a particular cognitive state, but are not medical diagnostic terms. Underlying these legal constructs is a specific definition of "cognition". This is either the ability of an individual to premeditate, deliberate, and form specific criminal intent (as pertains to homicide), or the cognitive capacity of an individual to understand and interact with others (as pertains to informed consent, aiding in one's own defense, etc.). While all of the DSM-IV mental illnesses discussed above can adversely affect on "cognition", it is important to understand that the measurement of "cognition" from a forensic standpoint (and also from a neuropsychological and neurophysiological standpoint) exists separate and apart from an specific DSM-IV diagnosis.
Neuropsychological and Medical Cognitive Testing
Neuropsychological testing is generally not performed by all psychologists, but is administered by a subset of Ph.D. degreed psychologists termed neuropsychologists. Neuropsychologists have specific training in the administration and interpretation of specific cognitive assessment test batteries. In addition, thorough neuropsychological testing has built into it paradigms to assess for the presence of symptom amplification or malingering for secondary gain, important issues when presenting a psychiatric defense. While the nuances and subtleties of neuropsychological testing are beyond the pall of this particular document, there are other authoritative texts to which the reader is referred.
Neuropsychological assessment is generally composed of a battery of tests administered to an individual that measure against statistical norms that person's ability to "think". A neuropsychologist generally administers a battery of 10 - 12 tests that specifically key on certain domains of cognition, such as attention, concentration, short-term memory, information processing speed, visual memory, visual recall, executive functioning and the like. The neuropsychologist then synthesizes this information in the form of a report that seeks to dimensionally categorize the presence or absence of specific cognitive deficits in an individual and the degree of impairment present in each of these cognitive domains.
It is important to note that cognitive deficits can exist across the spectrum of psychiatric and neuropsychiatric disease, such that individuals with schizophrenia, mood disorders, dementia, delirium, and other neuropsychiatric disorders will all to a greater or lesser extent exhibit cognitive deficiencies on neuropsychological testing. In addition, many of the medications used to treat psychiatrically impaired individuals can cause cognitive deficits of their own. Finally, acute and chronic drug and alcohol abuse can also result in demonstrable cognitive deficits on this type of testing. Thus neuropsychological assessment can statistically categorize the presence and severity of key cognitive deficits in a criminal defendant, and in many instances is necessary to demonstrate to the court and/or a jury the presence and "cognitive" severity of the psychiatric illness at issue.
Medical and neurophysiological testing
In addition to neuropsychological testing, cognitive abnormalities can be demonstrated through neurophysiological testing. These physical tests of actual brain anatomy and function include:
The use of static testing, such as CAT scans (CT) and Magnetic Resonance Imaging (MRI) to look for anatomic brain abnormalities (atrophy, injury, stroke, brain malformation, etc.).
The use of neurophysiological testing including Electroencephalography, brain stem and visual evoked responses, and P-300 neurophysiological testing to demonstrate brain electrical conduction (e.g.- "wiring") abnormalities.
The use of dynamic neuroimaging, such as Positron Emission Tomography (PET) or Single Photon Emission Tomography (SPECT) scanning, to delineate metabolic or blood flow abnormalities in specific regions of the brain associated with a specific cognitive deficiency.
Again, these tests are dimensional in nature and will detect appropriate abnormalities in many of the psychiatric disorders noted above. These types of tests are useful adjuncts in characterizing the presence and cognitive severity of the various psychiatric diseases discussed above. If any one test is used alone to "prove" a specific psychiatric defense, this over-reliance on a single medical technology may be subject to a Daubert hearing.
Finally, there are a variety of common medical conditions that can cause or augment specific cognitive abnormalities in both psychiatrically ill and psychiatrically well individuals. These would include:
The cognitive/brain effects of chronic heart and vascular disease.
The cognitive/brain effects of endocrine disorders, such as diabetes and thyroid disease.
The cognitive/brain effects of autoimmune disorders, such as systemic lupus erythematosus.
The cognitive/brain effects of specific non-psychiatric medications.
The cognitive/brain effects of neurotoxins (e.g.-lead, solvents, etc.).
The cognitive/brain effects of other non-psychiatric medical conditions (e.g.- cancer, HIV, etc).
Again, there are literally thousands of medical, toxicological and medication-related cognitive effects that can impinge on both "psychiatrically ill" and "psychiatrically well" individuals, and may have pertinent ramifications in demonstrating cognitive abnormalities in specific criminal defendants. However the scope of this discussion is so broad, that it cannot possibly be encompassed in this text.
In summary, the comprehensive dimensional assessment of a criminal defendant's cognitive status should include not only the rendering of the DSM-IV diagnosis and an appropriate report by an expert, but should also include the judicious use of neuropsychological and neurophysiological testing (and, where appropriate, medical testing) to buttress these conclusions.
The Expert's Report And The Dimensional Assessment Of Cognition
When engaging a mental health expert to evaluate a client, you should ask the expert the following questions:
Does the patient have a medical/neurological condition that could affect cognitive functioning?
Does the patient take any medications that could affect cognitive functioning?
Does the patient have a history of toxin exposure that could affect cognitive functioning?
Have you done, or will you refer the patient for cognitive testing by a bonafide neuropsychologist?
Have you done, or will you refer the patient for neuroimaging and/or neurophysiologic testing to demonstrate brain physiologic abnormalities?
Have you requested the patient's past medical records and/or ordered current medical tests to evaluate for non-psychiatric disease related causes for any cognitive abnormalities?
Not every defendant will require all of these tests, and none of these tests can stand alone as "proof" of a particular type of cognitive deficit. However, this type of ancillary testing is reflective of the modern age of mental health, and should be part of any comprehensive psychological/psychiatric evaluation of a mentally ill defendant.
Lawson F. Bernstein, M.D., is a board certified forensic neuropsychiatrist, with subspecialty expertise in the assessment and treatment of closed head injuries, stroke, toxic environmental exposure, chronic pain conditions, and other neuropsychological/neuropsychiatric conditions.
See his Listing on Experts.com.
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