Logo — Neuro Psych Evaluation
Logo — Neuro Psych Evaluation

 LEAD POISONING

“You will see…that the Opinion of this mischievous Effect from Lead is at least above Sixty Years old; and you will observe with Concern how long a useful Truth may be Known and exist; before it is generally Receiv’d and practis’d on."                                                                                   Benjamin Franklin, July 31, 1786 

"The modern history of lead poisoning is a sad tale of inexcusable disregard for knowledge that has long existed."                                                                Jane S. Lin-Fu U.S. Dept. of Health and Human Services, 1994

 


Dr. Newman has extensive experience in the evaluation of lead exposure for several law firms. One firm noted, “Dr. Newman is our primary resource for neuropsychological evaluations; we depend on his expertise for accurate evaluation and description of a client’s functioning. His reports provide comprehensive, relevant and vital documentation for litigation. Most salient in these cases is his evidence-based data for distinguishing pre-existing conditions from lead exposure-related difficulties. In interview and occasional cross-examination, he offers knowledgeable explanation of neuropsychological testing, brain function, and behavioral causation as it relates to a plaintiff. He clearly states when any data is too vague to provide clarity. His reports are expertly written and he is verbally facile with a large body of information; in almost all cases, a settlement is reached in favor our clients."

Dr. Newman has researched the current literature for several legal firms. Here is some of the relevant information that this evaluator uses in writing his evaluations:

Neuropsychological tests focus on behavioral functions controlled by neural systems. Due to the insensitivity of IQ tests to assess effects of brain injury, neuropsychological tests have been receiving increased attention for the description and effects of lead exposure. As documented above, these studies have reported deficient performance on tests that assess fine motor skills, language, aspects of memory, attention and executive functions. For example one study found that the lead poisoned group was deficient in 3 of 4 aspects of fine motor functioning, 4 of 4 aspects of visuopercceptual abilities, 4 of 4 aspects of memory, 7 of 8 aspects of language, 2 of 3 aspects of attention and 4 of 4 aspects of executive functioning.

Brain injuries from most etiologies do not generally produce general dulling, so if generally dulling were the case, this would be a rather unique set of symptoms. Unfortunately, the impression that childhood lead poisoning causes this generalized pattern is an artifact due to the use of test scores averaging in group studies.

The methodology and rationale underlying a clinical neuropsychological assessment of an individual gives a view of the client’s deficits which would be overlooked by those who are not familiar with its methodology. Neuropsychological testing in a clinical setting is designed to measure cognitive/behavioral manifestations of normal and abnormal brain function in an individual to see if a diagnosis of brain injury is appropriate. Functional scanning is increasing confirming that these injuries relate to identifiable discrete or distributed neural systems. These functions are broadly categorized as sensory/perceptual, motor, language, attention, memory and executive. Each of these categories are subdivided: for example, major processes subsumed under the rubric of memory include free recall, working memory, procedural and episodic memory with different systems for remembering auditory, verbal and visual information.

Decisions as to whether or not there is abnormality are based on the pattern of test results rather than on any individual score in isolation. The underlying rationale is that with the majority of brain injuries, some neural systems are unaffected, while the functioning of others are diminished. The neuropsychological functions mediated by the damaged areas will be negatively impacted, while the behaviors controlled by the intact systems will be less affected. Accordingly, neuropsychological test performance that depends on behaviors controlled by damaged areas will decline, while tests less reliant on such behaviors will be normal.

To determine whether a depressed test score represents the normal fluctuation of cognitive strengths and weaknesses in an intact individual rather than a score indicative of impairment due to brain injury, use is made of a standard of comparison specific to that individual. Lezak states, “ Determination of a baseline rests on the well founded assumption that under normal conditions …there is one performance level that best represents each person’s cognitive abilities and skills generally.” Accordingly, test performance that is significantly below expectations for an individual’s overall level of cognitive functioning is considered to be abnormal. Test results that are at least one standard deviation below an individual’s baseline (Hebben & Milberg, 2003) or greater than one standard deviation (Lezak, et. al. 2004) are classified as clinically significant.

Based on the results of a neuropsychological evaluation, one can only conclude that functioning is normal or impaired. When impairment is detected, consideration of additional factors (e.g. medical records, lab reports, etc.) allows the additional conclusion of whether or not there is brain injury or some other cause for the test deficiencies. If the conclusion is reached that brain damage is the cause of the test results, one cannot (except in rare cases) determine the cause of that injury simply based on the specific pattern of behavioral performance. When a particular cause of brain damage results in a specific or unique set of symptoms that can be used for diagnosis, that clinical presentation is termed a signature injury. Unfortunately, most etiologies of brain damage lack a signature injury and typically produce different patterns of impairment in different individuals. Thus all pertinent information is considered and possible causes of the injury are identified, evaluated and ruled in or out.

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