DUI/OVI

The Aging Process and Field Sobriety Tests

Each year there are approximately 1.4 million DUI/OVI arrests (1 of every 139 licensed drivers) in the United States. In 2005, there were 16,685 alcohol-related fatalities. "Alcohol-related" fatalities are defined as at least one driver or non-occupant involved in the crash having a blood alcohol concentration of .01 grams per deciliter or higher. Field sobriety tests are a mechanism to convict people - not test whether they are sober. Standardized field sobriety tests are a witch-hunt being perpetuated by law enforcement on our own people. Even a recent 2006 NHTSA publication admits, "Road tests have long been considered the gold standard for measuring driving ability. They have widely recognized limitations." One would not know this visiting the courtrooms across America. This article addresses one of the most commonsense problems contributing to false convictions - the condition and age of the subject.

Dr. Marcelline Burns, developer of the standardized field sobriety tests (SFST's), has conceded that the tests were not designed to determine impairment of driving. So what relevance do the SFST's have in determining whether or not a person is driving while intoxicated or driving under the influence? There is not much relevance, particularly when a person's condition and age are considered. It is well documented that the normal aging process is accompanied by deterioration in sensory functions and motor performance. Sensory functions necessary in communication also show increased impairment with age. Age-related slowing in cognitive and motor processes includes longer reaction time and movement execution time. This is due to increased neural noise, which results in signals being less well detected in the central nervous system.

Test Components

After being stopped by law enforcement, a driver will often be asked to perform a field sobriety test. For the "one leg stand" test, the police officer will ask the driver to stand with his hands at his sides, raise one leg six inches above the ground, and count to 30. The "walk and turn" test involves a driver taking nine steps (heel to toe), turning around, and taking nine steps back. When administering the "horizontal gaze nystagmus" test, the officer checks the driver's eyes for indications of impairment while the driver follows an object that has been placed approximately 12 inches in front of his face.

Although not a standardized test for DUI/OVI, in some jurisdictions the Rhomberg test is still administered. This is a medical test used to detect the presence of brain lesions, and is clearly inappropriate for forensic purposes. Police routinely use the test for sobriety testing purposes. Subjects are asked to hold their heads back, close their eyes, and estimate the passage of 30 seconds. This test is skewed with or without alcohol or drugs because one's natural vestibular system sways to adjust for postural balance, becoming more pronounced with age. Head flexion or extension deteriorates postural stability as a result of vestibular input even where visual information is kept the same.

Motor Skills and Memory

Before SFST's were developed, in the early decades of experimental psychology, it could already be shown that skill learning ability and motor performance accuracy deteriorate with increasing age. The original SFST data seemed to take this into account by setting 65 as the upper limit to SFST usefulness. Categorizing the effects of age chronologically as the SFST's do by stating a 65-year-old age limit is both arbitrary and false. Aging actually results in increasing biologic diversity so that we become less alike as we age. Biologic and chronologic ages are not the same, and body systems do not age at the same rate within an individual. The bio-psychological state of a person is important, including most notably fitness and nutrition. It is empirically well supported that these factors improve attention and psychomotor performance across all age groups.

The National Highway Traffic and Safety Administration (NHTSA), much akin to the arbitrary cutoff, 65 years of age, also references that an individual 50 pounds or more overweight may have difficulty with the one leg stand test. Particularly relevant is the fact that 64.5 percent of Americans are overweight and 30.5 percent are obese. Regarding physical fitness, the annual number of lives lost through physical inactivity is estimated at more than 250,000 per year. With respect to the aging process, there is a gradual decline in performance, as opposed to an abrupt drop off of cognitive and motor skills, as seen in the case of an acute stroke. In short, a gradual decline in cognitive and motor processes results from chronological age, fitness, and nutrition in a given individual.

Changes within the brain are primarily responsible for a loss of motor skills. Dopamine receptors within the brain are linked to locomotor functions and learning. Dopamine neurons account for less than one percent of the total neuronal population of the brain but have a profound effect on motor function. They act as chemical messengers similar to adrenaline connecting the brain processes that control movement. Dopamine neurons in basal ganglia decline 5-10 percent per decade. Parkinson's disease suffers are a prime example of loss of control of motor activity in regards to dopamine neuron loss. Declining hormone levels that occur naturally compound the affect of dopamine neuron loss. Several studies have shown that testosterone positively affects performance in certain cognitive domains such as memory and spatial ability. In an academic study of men and 48-80, it was shown that older men with less testosterone had lower levels of function in working memory, speed, and attention, as well as spatial relations. For men, the use of synthetic hormones did not mediate the performance problem. The same proved true for aged women in the administration of synthetic estrogen.

Memory becomes relevant under many scenarios of the DUI/OVI investigative process, from short-term capacity that includes remembering instructions to longer-term memory in cooperating with interrogations. The phenomenon of memory aging begins in the 20s among aging adults who report themselves in good health. Aging memory affects us all, not just those with significant memory disorders such as Alzheimers. In the periods of early and middle adulthood, the memory-aging phenomenon is associated with a shift of the entire distribution of memory. It is not simply attributable to a small percentage of individuals experiencing large memory loss due to pathology, with the remaining individuals maintaining the same level of performance.

In a study using a dual-task combination of walking and memorization, it was revealed that older adults prioritized the sensorimotor brain function over the memory task to avoid a loss of balance, resulting in a performance decrease of the memory task. This explains how the counting may suffer on various field sobriety tasks as the subject focuses more on the physical tasks of balance, regarding the walk and turn and one leg stand tests.

There is a distinction in the memory regarding automated effortful processing where the effects of aging increase the amount of effort required in the performance of new, unlearned or unnatural coordination patterns. This explains why so many people perform a pivot on the walk and turn exercise versus taking a small series of steps. First, they do not comprehend the turn instructions well because of undue focus on the sensorimotor skills needed to maintain an unnatural and difficult positional stance. The turn itself is a new instruction on an unnatural turn pattern normally encountered in everyday settings.

Older adults have much more difficulty with the performance of new tasks, albeit slight, due to the additional cognitive load that must be engaged for learning to occur. Sensory memory lasts much less than a second and, because of sensory changes that occur with aging, this puts the aged at a disadvantage. Consequently, older people have much more difficulty in adjusting to the positional stance of the walk and turn, which requires a high level of sensorimotor control. Normally, this level of control is not required unless one is engaging in tightrope walking or gymnastics on the balance beam.

Attention Tests and Balance

Clearly the SFST's are divided attention tests. It is known that the rate of shifting attention between different sources shows a clear-cut reduction with age. A research project supported by a seed grant from the Center on Aging and Cognition demonstrated on a simple gripping test combined with recitation that, even after intense practice, older adults needed more attentional resources than younger adults to perform a dual-task. This proves that cognitive performance and force control are interconnected in older adults. In a dual-task bicycling and counting test where the subject had to bicycle in a certain direction and count the number of times an image appeared on a computer screen, it was found that performing the coordination patterns together with the attention task caused a decrease in phasing accuracy and stability in older versus younger people.

Driving is also a divided attention task. Driving, however, does not require the gravitational force control necessary in the one leg stand or memory number recitations to the degree called for in the walk and turn, one leg stand, or manual dexterity tests such as the "finger countdown." Older adults may experience temporary lapses of attention or executive control, which contributes to greater inconsistency or performance, as seen in variations of the same field tests both at the roadside and in the station. Higher anxiety has also been associated with poorer divided attention performance in older but not younger adults. Of course, basic psychomotor functions are required for a divided attention test, but basic too is the premise that age-related changes in psychomotor functions will affect the performance scores.

In a study involving 99 young people from ages 17 to 36, and 763 older people from ages 54-94 on a reaction time test, it was determined that variability between persons (diversity), variability within persons across time (inconsistency), were greater in older compared to younger adults even when group differences in speed were statistically controlled. Studies contrasting younger and older adults have all found increased inconsistency in response time distributions with increasing age.

Most DUI/OVI's occur at night. This also puts older people at a disadvantage. Across the adult lifespan there is a shift in the self-reported time of peak arousal or attention awareness. This shift reflects a tendency for the optimal time of day (TOD) to become earlier with advancing age. Since the earliest days of experimental psychology, it has been known that TOD can dramatically influence the efficiency of cognitive processing including short-term memory, sustained attention, inhibitory processing and semantic activation. Age-related deficits of working memory are magnified at non-optimal times of day. It is obvious that older subjects who have not been drinking at all will be disadvantaged compared to their younger counterparts. In an experiment regarding reaction time to a stop signal paradigm, there was a 20 percent difference in stopping efficiency between younger and older folks at non-optimal times (11 percent difference at optimal times).

Dizziness has been associated with stress. It is one of the most prominent symptoms of both panic attacks and hyperventilation. As one grows older; however, the disturbances with balance are greater compared to younger people. Of more notable concern is the fact that older people are less likely to view their dizzy condition as a self-perceived handicap. People tend not to seek medical treatment for conditions associated with normal aging or ailments of which there are no known treatments. This is particularly true for dizziness. In a study of 100 consecutive outpatients in the United States with dizziness, less than one-third received a diagnosis for which a treatment plan exists.

The symptomatic prevalence in the community for dizziness has been estimated at more than 20 percent, yet recorded annual consultation rates of less than two percent indicate this is a significant, silent, untreated problem. The lifetime prevalence rate of dizziness of Americans resulting from outpatient self reports has been estimated at 25 percent. What is alarming is the duration of dizzied impairment. In a London study of citizens aged 18 to 64, it was found that women were more likely to report dizziness than men; people under 36 were more likely to report nonhandicapping dizziness; and handicapping dizziness was significantly more common in individuals aged 36 to 64. Of more concern is the duration of symptoms: 26 percent reported less than six months, 44 percent between six months and five years, and 30 percent more than five years. More than half reported basic postural unsteadiness.

Maintaining a stance requires a greater portion of attentional resources in older compared to younger adults. Postural stabilization has to do with the role of afferent/efferent signals related to eye movements. Recent studies have shown that postural sway during pursuit of a moving target or when looking straight ahead in the darkness is higher than when fixating on a stationary target or nystagmus is suppressed. In the latter two, extra-ocular signals are reduced, resulting in less postural sway. Neck muscles are also involved in stabilizing the head during the horizontal gaze nystagmus (HGN) test; yet one's inability to keep one's head still is frequently used as a sign of intoxication or inability to follow directions. Horizontal gaze position is associated with head neck muscle activity. It is difficult not to move the head when focusing. In fixed head subjects there is a dynamic coupling of the neck splenius muscle, and horizontal eye position with the oculomotor brain command being distributed to both eye and neck muscles.

In a moving platform experiment, participants were placed on a stationary platform under various conditions, and it was found that healthy older adults had considerable more difficulty maintaining balance both with and without the cognitive task of counting backwards. Platform conditions varied with side-to-side and front-to-back movements simulating real world conditions where one might be asked to perform the SFST on an unlevel surface.

It is preposterous that in the quest for more convictions, the recent NHTSA SFST manual goes so far as to say, "Recent field validation studies have indicated that varying environmental conditions have not affected a suspect's ability to perform this test." Motor control and postural control are inextricably linked. If the surface are or testing conditions do not support basic postural control, performing a walk and turn or one leg stand test is inherently flawed. All motor tasks, unless performed while a subject is fully supported, require complex interactions of postural adjustments to maintain intersegmental coordination and equilibrium during the task.

Hearing and Vision

The peripheral sensory functions of hearing and vision tend to show increased impairment with age, suffering remarkably after age 50. Many visual changes accompany the aging process even in the absence of known visual pathology. Among these changes that normal adults exhibit are a loss of contrast sensitivity, shrinkage of the "useful field of view," a decrease in central and peripheral acuity, spatial vision and a weakening of the cognitive control of eye movements. Translated to the real world practicality of HGN, older adults have difficulty converging their eyes to focus on a target at a close distance. Older adults are less able to smoothly pursue a moving stimulus. Tracking an object shows clear-cut age deficits. Following the stimulus in general is more difficult because reaction time in dealing with visuo-spatial tasks has been proven to slow for older adults. Age differences in oculomotor control translate to saccadic movements (lack of smooth pursuit), which have greater latency and slower peak velocity.

One might argue that the ultimate test in a DUI/OVI investigation is the actual operation of a motor vehicle with vehicle accidents reflecting intoxication. As there are obvious reasons for accidents outside of intoxication, it is important to note age-related concerns in automobile accidents. One age-related analysis of traffic accidents in Finland showed that attention fatigue is a drastic factor in traffic accidents. Most DUI/OVI's are not occurring at optimal TOD for older people. One's useful field of view, which diminishes with age, also turns out to be a good predictor of increased driving accidents.

Age-related hearing loss is the most common type of hearing impairment in humans. Sixty percent of people older than 70 have hearing loss of at least 25 decibels. The prevalence of hearing loss among middle-aged people is not well known. In a comprehensive study of hearing loss in Beaver Dam, Wisconsin, of people of aged 48-92, 46 percent had some form of hearing loss. It was found that for every five years of age, the risk of hearing loss increased by almost 90 percent, with men being four times more likely to have hearing loss than women. Education and income level were inversely associated, with people who had not completed high school being 2.42 times more likely to suffer hearing loss compared to those with a college education. Those earning less than $30,000 a year were approximately twice as likely as those earning $60,000 a year to suffer hearing loss largely due to occupational exposure.

Hearing impairment increases with age. The most common hearing loss occurs at higher frequencies making speech especially difficult to understand against background noise, like the roadside noise of a typical DUI/OVI setting. Temporal resolution is necessary to distinguish the background noise in everyday listening situations. The "precedence effect" refers to the finding that short onset-to-onset stimulus delays and leading and lagging sounds will perceptually fuse into a single auditory image. Even older people with normal hearing sensitivity perform more poorly than younger listeners on a precedence-effect task. Both temporal resolution and the precedence effect deteriorate with age and hearing loss, with temporal resolution more closely associated with age than hearing loss.

Walk and Turn

Considering the fact that the walk and turn test is not fully demonstrated to nine steps, people who suffer temporal resolution even without hearing loss as well as those with hearing loss may miss the important instruction of taking only nine as opposed to 10 steps, thus making them appear intoxicated. A subject in not asked to repeat the instructions on the SFSTs - only that they are understood.

The walk and turn is a tightrope exercise requiring an unnatural coordination of muscles and balance. By the time one reaches the age of 60, maximum muscular force is reduced by about 50 percent and the maximum movement speed up to 90 percent. There are both automatic and effortful processes involved in movement control. When it comes to walking, healthy older people select strategies that maximize stability when balance is perturbed. For example, in a test where older people were asked to walk a Figure 8 in order to maintain balance, they shortened their steps. Normal age related decline in leg strength may be the primary limiting factor that prevents older people from walking at an equivalent speed to younger people. Differences of walk are even more pronounced between older and younger people when walking on irregular surfaces. General differences of gait between a younger officer and older citizen on video reflect age-related declines in body systems, and yet are deceptively portrayed as signs of a slowed central nervous system due to alcohol or other depressants.

Miscounting is often offered up as a sign of intoxication or the loss of the normal use of one's mental faculties. Although it is not a technical clue on the SFST guidelines, optional tests routinely used by officers such as the "finger countdown" or "hand slap" test penalize citizens for miscounting. In an exercise where the subject, while attempting to maintain balance on a moving platform, was asked to count backwards in threes starting from random numbers with no alcohol or drugs involved, out of 20 younger adults the average number of correct responses were 12.5 +/- 2.9. For 20 older adults, the average number of correct responses was 9.8 +/- 2.6. Recent brain imaging data has shown that during performance of repetitive finger or wrist movements, the aging brain must recruit additional sensorimotor regions. In this way, age-related proprioceptive processing deficits compromise motor functions for which sensory information is of critical importance.

A study in two British towns administered the one leg stand to 70 patrons as they left a bar. The majority of those tested ranged in age from 18 to 36 (therefore not even inclusive of the older aged population) with only 23 deemed under the influence of alcohol or a drug. Researchers determined that the majority of people failed the one leg stand, making it an unfit test to determine impairment.

Scientific Reliability

The problem with the widespread promulgation of SFSTs in the alcohol and drug arena by American NHTSA - related psychologists is the lack of true scientific reliability as opposed to purported self-serving statistics, which amount to "face validity." In a study analyzing a sample of 38 papers from 16 journals covering all the major types from 1972 to 1988, no papers were found to have documented true scientific reliability or validity.

Although Dr. Marcelline Burns has been widely quoted in her 1995 study, which claims "validation" for the SFST test battery, the validity of these tests has been questioned. This is no different than the problem with the drug recognition expert (DRE) validation: "It has to be acknowledged the author of the initial studies which tended to validate the DRE program, was intimately associated with the DRE protocol and involved n the L.A. test which "touted' the DRE accuracy." As stated in the peer reviewed Journal of Clinical Forensic Medicine. "No evidence has been presented that there is any correlation between a person's performance on any aspect of the battery of tests used in FIT (field impairment testing, i.e., SFSTs in the United States) and that person's ability to drive. It is our belief that the use of these tests has led, and will continue to lead, to the arrest and conviction of motorists whose only crime is that they cannot 'pass' the FIT procedures."

The Association of Forensic Physicians stated: "Field Impairment Testing (FIT) as currently performed in the UK has not been validated and there is increasing anecdotal evidence that errors of interpretation are being made which could lead to wrongful convictions." Put simply, the problems with SFSTs are that they only account for one variable - a person's performance at the time of testing - without accounting for any other variables. An experimental design systematically manipulates independent variables to discover their effects on dependent variables. To attribute cause and effect correctly, all other variables must be controlled, usually by eliminating those that cannot be eliminated, counterbalancing those that cannot, or measuring those that cannot be eliminated or counterbalanced.

The problem with the SFSTs is that there is no consideration of the variables such as age and pathology. Variables that are not accounted for can confound the results in the psychometrics of testing, making it impossible to distinguish which variable has caused which effect. The SFSTs are an incorrect testing matrix by design. Any psychological test should be valid, reliable, and sensitive in that it should measure what it purports to measure, do so consistently, and be capable in basic design of detecting changes in what it measures. Although these principles are commonly applied in areas of psychology such as personality, intelligence, and clinical occupational testing, they are rarely applied to performance assessment and hardly at all in the assessment of drugs on performance, as can be seen with the SFSTs.

As we age, the rate of decline is intra-individual. Individuals become less alike as a function of differences in change. Age-related decreases in performance and increasing intra-individual variability in neurobiological mechanisms in the brain drive increases in inter-individual differences in performance. Due to the fact that aging is a gradual process and most studies focus on the differences between the elderly and young populations, it is necessary to extrapolate across the ages that the physiologic decay of the body occurs over time.

Middle-aged people largely reflect the biologic changes that produce chronic degeneration affecting the body systems. Hypertension (high blood pressure) is one of the most chronic conditions for men and women over the age of 40, with one out of every three Americans suffering this condition. Blood pressure affects circulation within the brain, so vital to dopamine receptor health. High blood pressure has even been judicially recognized as a known cause for HGN. One of every four people over age 50 suffers from arthritis, which of course has obvious implications on the walk and turn and one leg stand tests.

Conclusion

Alcohol ingestion and driving are issues that shall continue to present themselves. The scientific and law community owes it to society to address the grave injustices currently employed in assessing whether or not one has operated a vehicle while intoxicated or impaired. It is imperative that a person charged with such an offense should hire an aggressive, experienced DUI/OVI trial attorney to represent them in their defense. At the office of James S. Arnold & Associates, such a defense is available.

Credit to Mimi Coffey's publication in the National Association of Criminal Defense Lawyers, January/February 2008 issue of the Champion.