Hippocampal Health

One of the main areas of neurogenesis in the human brain is the hippocampus, the temporary way station in your brain for information before a small portion (less than 1% of all of the information you receive) is retained as memory traces in other parts of the brain.

What determines what is retained? One factor appears to be the emotional salience of the information. There are several ways that this shows up. For example, early stages of dementia are marked by difficulty recalling recent experiences, but the difficulty is not uniform; some information is more easily recalled. Many older people who are struggling with everyday memory also have clear recollections of recent events that have made them angry or frustrated. The reason is that emotional salience causes information to be retained, even if the emotion is negative. Conversely, people who are happy and optimistic more often give their experiences positive emotional salience, resulting in disproportionate retention of information that tends to be recalled positively. For these people, the glass is not only half-full, the milk is cold and satisfying.

Now, stick with me on this next part, which may be important for your personal future. When positive information is self-referent (referring to your self-image), you feel better about yourself and you tend to evaluate experiences more positively, which leads you to be more resilient, even in the face of dire emotional and physical challenges. This resilience translates into handling stress better, which results in lower cortisol levels. This is important because high levels of cortisol damage and limit the growth of dendrites, the tiny spines that emerge from the cell body to link with other neurons. If cortisol damage is severe and long-standing, the neuron will die. Thus, positive emotional salience of information leads to emotional resilience, which leads to neuronal protection and hippocampal health.

I pay attention to my emotional inputs and try to avoid or minimize negative inputs. I find that my clients who have disorders involving depression and anxiety benefit greatly from guidance to do the same. Click on the hippocampus tag at the end of this post for the Happy Hippocampus activities I give my clients to stimulate positive emotional and cognitive development.

Neurogenic Development

Starting from a stem cell and maturing over three weeks into a fully functional neuron that begins to link with other neurons, neurogenesis offsets neuropathic losses caused by age, illness, or injury. The process continues throughout life, but ebbs and flows, depending on several factors.

Neurogenesis requires just-right challenges both to cognitive capacity and to aerobic capacity, within the context of good control of stress. Neurogenesis is occurring constantly, even now as you read this. The ebb and flow of neurogenesis changes throughout the day and continues as you sleep.

Because of the positive effect of aerobic activity on both stress and neurogenesis, I encourage my clients and students to integrate high-demand learning activities with aerobic activities. My wife Mary and I do that ourselves. For example, I often listen to podcast lectures on interesting but challenging subjects while I ride my bicycle on the Katy Trail. Mary reads while on the treadmill. When studying for important examinations, I encourage my students to audio record study guides and listen to them while walking. Rather than sitting and studying, walking and reading or listening is certainly more effective.

An excellent popular press treatment of this topic and its importance in education is Spark: The Revolutionary New Science of Exercise and the Brain (2008) by John J. Ratey and Eric Hagerman. The authors describe an educational program in Illinois that integrates physical education with demanding academic education. High school students are encouraged to participate in aerobic activities in zero-period and take difficult courses like calculus or physics or chemistry in the first half of the morning. The results are impressive, presented by the authors with adequate research references.

Educating High-Functioning Clients

Most people who become disabled as adults are curious about what has happened, as are their families. This is especially true for people who are high functioning and were in demanding jobs at the onset of their disability. I think part of the sense of frustration and anxiety that people experience is based on not knowing what is wrong. If they have ever had an explanation, most don’t recall. I think we can assume that this is not only technically difficult but emotionally difficult for people to understand when it is happening to themselves or loved one.

I routinely use visual aids, erasable markers, and a white board to provide an explanation of the underlying injury or disease process during my intake interview. Providing this education does not take much time and certainly helps to build rapport. I think it is also necessary if we are going to get the most from our clients in terms of compliance with rehabilitation activities that are often boring and show very subtle results, if any are able to be seen.

With regard to brain structure and function, I use plastic coated posters from the Anatomical Chart Company. The Anatomy of the Brain Anatomical Chart is a valuable asset. It includes basic brain anatomy and a simple drawing of a neuron. Find it at amazon.com ($18).

Recently, I began using an iPad 2 with the FINR Brain Atlas, an application from the Florida Institute for Neurologic Rehabilitation. I am amazed at the detail and functionality that I was able to purchase for $2. It is also available for the iPhone. Information is organized around anatomy as well as around nine different types of common injuries. I found the artwork for diffuse axonal injury to be especially useful in explaining to clients how they can have problems with function that do not appear in traditional CAT scans or MRI scans. The Atlas provides a text narrative describing what is on the screen. I found this information to be accurate and helpful, written for most consumers. Find the FINR Brain Atlas at itunes.apple.com.

I have also purchased a brain model that I found to be less useful and certainly not worth the $300 that I spent. One of the problems is that the brain itself is so unassuming that a model of the brain encapsulates its humility. It would be better to put the $300 towards an iPad 2.

Using Adjectives to Describe Ability Levels

The indication of ability levels by using adjectives is time honored but somewhat problematic. It was introduced by David Wechsler (Wechsler, 1958) and has been replicated in each of the examiner’s manuals for the various Wechsler scales in succeeding years.

What is always mentioned by Dr. Wechsler and his colleagues and successors in the examiner’s manuals is that (and this is always bolded), specific scores should always take into consideration the measurement error inherent in test scores (Wechsler, 1997) (p.25). Thus, the use of the term “average” with regard to the Wechsler scales describes performance that is plus or minus two-thirds of a standard deviation from the median.

This does not square with statistical terminology, in which “average” is usually referred to as plus or minus one standard deviation, connoting the average range. The qualitative descriptions proposed by various authors (click on thumbnail below to download or open PDF):

Ability Levels

Beginning with the Wechsler Adult Intelligence Scale—Revised, Wechsler substituted “Extremely Low” for “mentally retarded” because this “avoids the implication that a very low IQ score is sufficient evidence for the classification of ‘mental retardation’…” (Wechsler, 1981). Neuropsychologists continue to use “retarded” (Lezak, 1995; Lezak, Howieson, & Loring, 2004), although “Impaired” is gaining acceptance (Mitrushina, Boone, Razani, & D’Elia, 2005).

In my own practice, I avoid using adjectives, preferring to use percentile rankings. This is especially important with a person who was high functioning before the onset of their disease or injury. Such a person may actually have a rating that is considered “impaired” if their score on the instrument is in the average range. Additionally, my examinations focus on functional limitations, so that using the word “impaired” suggests that I am actually focused on impairment, which is lower on the Stage Model.

  • Lezak, M. (1995). Neuropsychological Assessment (3rd ed.). Oxford: Oxford University Press.
  • Lezak, M., Howieson, D., & Loring, D. (2004). Neuropsychological Assessment (4th ed.). Oxford: Oxford University Press.
  • Mitrushina, M., Boone, K., Razani, J., & D␁Elia, L. (2005). Handbook of Normative Data for Neuropsychological Assessment. Oxford: Oxford University Press.
  • Wechsler, D. (1958). The measurement and appraisal of adult intelligence. Baltimore, MD: Williams & Wilkins.
  • Wechsler, D. (1981). Wechsler Adult Intelligence Scale—Revised Administration and Scoring Manual. San Antonio, TX: The Psychological Corporation.
  • Wechsler, D. (1997). Wechsler Adult Intelligence Scale—Third Edition Administration and Scoring Manual (Third ed.). San Antonio, TX: The Psychological Corporation.

Approximating Pre-Injury Cognitive Capacity

I have just completed a forensic case in which one of the key issues was the brain-injured client’s pre-injury cognitive capacity. This is always a difficult issue to pin down and is usually best handled either with grades from school, academic standardized tests, or pre-injury occupational performance.

With the first two, it is straightforward to use either grades or standardized tests as a baseline because normative comparisons are available for the popular intelligence or achievement tests that we can administer to the client.

However, my client was educated overseas and did not complete secondary school in his home country. He came to the United States in his early 20s and was injured at about age 40. In the interval, he worked as an athletic trainer on an entrepreneurial basis. That is, he did not go to college or graduate school and obtain the available certifications that have an academic basis, but was very successful in selling his services to sophisticated clients in the entertainment industry and the professional sports industry. He was so well-recognized that he was earning about $200,000 per year at the time that he got hurt, approximately 3 times the annual earnings of the 90th percentile athletic trainer, based on data from O*NET.

Using this information, I was able to use the O*NET Cognitive Abilities data that are the basis of the Cognitive Abilities Profile (CAP) that previously has been distributed to Clinical Research Consortium participants. Click on the thumbnail below to view the CAP for athletic trainers:

Cognitive Ability Profile

With this profile, I was able to successfully argue that my client’s pre-injury cognitive abilities approximated those of athletic trainers, based on the assumption that he had been successfully competing for employment as an athletic trainer.

Using the standardized data from this profile (the Z-scores are directly convertible to standard deviations, which are a close approximation of percentile rankings) it was easy to argue that his pre-injury cognitive profile ranged from high-average to above-average for the seven out of 10 cognitive abilities that are in that range in the profile. Comparison of his intellectual function data from the neuropsychologist and his occupational performance data from my testing allowed me to successfully argue that he would be unable to return to work as an athletic trainer.

This is a pretty typical application of the CAP, and is especially important and useful when we don’t have trustworthy pre-injury academic performance data. In some cases the academic performance data are quite old and were obviously eclipsed by subsequent occupational performance, while in other cases (like the present) the academic performance data are just unavailable.