INVESTIGATION OF THE EFFECTS OF SECOBARBITAL ON COGNITIVE AND PSYCHOMOTOR SKILLS RELATED TO DRIVING AN AUTOMOBILE

The effects of a 100 mg. dose of secobarbital was measured on a cognitive and psychomotor test of human behavior presumably related to driving an automobile. Eight healthy subjects, six female and two male, ranging in age from 25 to 40 years were tested by means of a simple math test and a pursuit rotor. Each subject underwent three separate drug experiments and during each was tested at one hour and at three hours after secobarbital administration. Blood samples were taken immediately before the one and three hour testing sessions in each drug trial. Quantitation of the secobarbital was accomplished by gas chromatography using a 2.5% SE-30 column. Secobarbital was found to significantly impair both the cognitive and psychomotor functions of behavior as measured by the math and pursuit rotor tests respectively at the one hour time interval after secobarbital ingestion. Only in the second drug trial did a psychomotor impairment persist at the three hour time period. Blood levels of secobarbital showed a correlation with percent change in psychomotor performance at one hour with the pursuit rotor test results and with the combined one and three hour pursuit rotor test results. Rank-order correlation was also shown. Math test results did not show correlation with blood levels of secobarbital. The time since secobarbital ingestion appeared to be

With respect to the Implied C:Onsent Law of the lt>tor Vehicle C:Ode Act of Rhode Island as amended and effective Septanber 1, 1973, it is "unlawful and punishable for any person who is a habitual user of or under the influence of any intoxicating liquor, narcotic drug, barbiturate, toluene, or any central nervous system stinulant to drive an autarobile." Alcohol, unlike drugs in general, is one substance 'Which has been thorougltly studied by many researchers to determine its effects on psychom::>tor skills as they relate to driving an auta:oobile. There are well standardized tests 'Which can identify and measure quantities of alcohol within a person's blood stream and entire body. C:Orrelation between the anount of alcohol in a person's blood stream and the psychom::>tor effects caused by it has progressed to the extent that legislators have been able to enact laws to govern its abuse in autonnbile traffic circumstances. Definite amounts of alcohol in a person's blood stream, i.e., 0.10% by weight, have been shown to definitely cause impainnent of psychorwtor perfonnance.
Similar infonnation with regard to drugs and their effects on psychoontor perfonnance does not exist. Due to the difficulty in predicting the effects of drugs, under uncontrolled circumstances, on psychorrotor skills, one carmot show with certainty if a drug when detected in the blood stream in therapeutic aroounts is actually causing a psychorootor impainnent. The inability to prove the correlation between blood levels of drugs and spycharotor impainnent is due in part to lack of sufficient research done in this area. Research that has been done has correlated a given dose of drug with an impairrrent of human perfonnance, but has not attempted to correlate blood levels of drugs and the psychorrntor impairrrent caused by them.
To this end a study is proposed that will attempt to detennine if a correlation exists between blood levels of secobarbital and impairrrent of a psychormtor and cognitive skill used to drive an autorrnbile. The study will involve eight young, healthy, adults who will be given 100 rngs. of secobarbital sodhnn and at pre-detennined intervals undergo ~ tests that relate to sare of the skills needed to operate a rrotor vehicle. Just prior to the tests, a blood sample will be taken and the level of secobarbital present in the blood stream detennined. Evaluation of the psychorrntor tests in the light of the secobarbital blood levels will be made.
Secobarbital, as a representative of the barbiturate class of drugs, was selected as the test drug for this investigation because of its popularity and availability on both the licit and illicit markets. Barbiturates are arn:mg the m:>st frequently prescribed sedative-hypnotic drugs and secobarbital is one of the roost popular fast acting barbiturates. The adult average dose of secobarbital is 50-200 rngs. daily for sedation and 100 mgs. at bedtine for sleep induction. (Swinyard and Harvey, 1970).

II. LITERATURE REVIEW
Driving an autOTIDbile is a highly complex psychCtIDtor and perceptual task 'Which is therefore subject to irnpainnent by any factor 'Which significantly alters the physiological and/or psychological state of an individual.
With the passage by the State Legislature of the Implied Consent Law previously referred to, an attempt has been made to reroove fran the highways of Rhode Island those people who either knowingly or unknowingly drive an autOTIDbile 'While under the influence of drugs. The use of mind altering drugs other than alcohol presents a serious contanporary problem. The exact proportion of the population of the United States using mind altering drugs is. not known and to even a lesser extent the proportion of those mo use drugs and drive an autonnbile. HCMever, the fact that alcohol and drugs, alone or in combination, are associated with over 50% of highway fatalities is a well known and docurrented observation. (Milner, 1972 It states that at any tine, 10 to 2rf% of the driving population is using a prescribed drug. According to a California survey (Manheiner et al, 1968) , 12% of men and 22% of WCXIEn reported that they legally used prescription or non-prescription stimulants, sedatives, or tranquilizers frequently.
Four percent of men and 8% of warren reported using sedatives, 6io of men and 14% of warren used tranquilizers, and 5% of men and 8% of women used stimulants.
The results of two independent surveys reported by Parry (1968) indicate that "about one-fourth of the U. S. adult population currently use one or another of the legal psychotropic drugs--sedatives, tranquilizers, and stimulants." "Currently" is interpreted to mean within twelve nnnths prior to the survey questionnaire. Results indicated that 13% of the specimens shaved the presence of a prescription drug. In all, 29 different drugs -were found of which the largest proportion were of the sedative-hypnotic type.
In another interesting study conc:h.Icted by Glauz and Blackburn (1975) involving the auto drivers of Lincoln, Nebraska and Miami, Florida, it was shown that approximately 4.3% of each group evidenced the presence of one or nnre of the 41 drugs for which tests were conducted. The drivers were randomly stopped at times and places of previous fatal accidents. Breath, urine, blood, and lip swab specimens were requested.
Surprisingly, a cooperation rate of 7' <5%, was achieved. One thousand and twenty-nine urine samples and 840 blood samples were collected and in these samples, sedatives particularly phenobarbital ·were the nnst can- In the presence of ethanol, the action of diphenhydramine was potentiated in two tests. The depressant properties of the antihistaminics studied was rruch rrnre apparent to the subjects than that of ethanol, and yet, significant impainnent was observed only with alcohol.
In a similar fashion, Hughes et al, (1965)  improve performance and arrobarbital tended to cause a decrease in perfonnance ability. Results were interpreted to show th.at those in the drug group had their performance altered because their motivation to do well in the tests was altered by the drugs. It is presupposed that arrphetamine and arrobarbital effect that part of the C. N. S. that is connected with 'M:>rk motivation. One might also infer here that anobarbital and arrphetamine would alter the motivation needed to control physical perfonnance required to drive an autanobile. Betts et al. (1972) showed the effects of chlordiazepoxide, amylobarbitone sodium, trifluoperazine, and haloperidol on actual low speed driving perfonnance tests; ~ie. weaving, parking, and gap estimation.
One hundred subjects, 50 rren and 50 w~n. were tested. Results showed an effect on low speed driving perfonnance with each drug with the possible exception of haloperidol. Also of importance :in this study was the indication that those subjects effected by the drug in question were unaware they were being effected. Results obta:ined :in this study would have taken on a greater significance if they could have been correlated with actual drug blood levels. Linnoila and Ha.kkinen (1973) sho\\ed the effects of diazepam and code:ine alone or :in conbination with alcohol on sinrulated driving :involv:ing 70 professional drivers. Every subject drove for 40 minutes beginning 30 minutes after ingestion of drug and drink :in a Sim-L-c.ar.
The aim of the study was to show drug :induced risks for traffic, not to show minimal irnpainrent of skills . Results showed that the drugs could :increase risks :in driving. Alcohol :induced one to neglect :instructions; higher doses of diazepam effected one's ability to react :in errergency situations; those subjects taking code:ine were less :indifferent to their surroundings but tended to drive off the road m::>re than those taking alcohol or diazepam; code:ine and diazepam taken in combination with alcohol slightly reduced the alcohol :induced negligence of :instruction; and potentiation of diazepam and alcohol was :indicated.
The use of a Si.rrrL-Car or any similar driving sinrulator to determine psychorrotor irnpainrent induced by drugs was confirrred by L:innoila and Mattila (1973). Tests :involving clutch, brake, gears, flashing lights, and changes :in steering and speed were recorded. The driv:ing period was 40 minutes start:ing 30 minutes after drug :intake. TI1e drugs used :in the exper:i.rrait were diazepam, code:ine phosphate, and isoniazed given in canb:ination with alcohol. Results confirrred a previous study with these drugs and alcohol with regard to driving skills. (Linnoila and Mattila, 1973). Results also suggested that simple tests could be used to predict drug interactions that would reduce driving skills. These results would also indicate that under controlled situations, drug dosage levels give sorre results that can be correlated to driving behavior; but in uncontrolled circt.nnStances, that is when one does not know how much drug was taken or when it was taken last or how rrruch food was ingested with the drug, etc., it v;ould seem that only a blood level figure would have direct meaning with regard to perfonnance.
There are a nurber of other laboratory studies that have been conducted using a variety of drugs to show their effect an psychorrotor perfonnance as it relates to driving an autormbile. Linnoila (1973) used atrophine and glycopyrrhanium in corrbination with alcohol. Landauer et al. (1973) derronstrated the effects of benzoctamine, a drug similar to diazepam, and alcohol on a battery of rrotor skill tests. Adams (1974) compared the effects of butabarbitone and nitrazepam an five short psychological tests designed to measure perfonnance :i.rnpainial.t. Dureman and Nornnan (1975) showed the effects of clorazepate and diazepam on a series of physiological and psychormtor tests. Seppala et al. (1975) (Bruning and Kintz, 1968) to detennine mether the percent change in performance in the test subjects was significantly related to the blood level of secobarbital detected, and linear regression analysis (Johnson, 1976) of the percent change in perfonnance versus the blood level of secobarbital to detennine the best line of fit between the two sets of data was done.

N. RESULTS
For a period of approximately two nnnths prior to the actual drugging experiments, the test subjects went through the testing procedures in order to familiarize themselves with the equiprn=nt and test requirements. After each individual had been tested between six and eight times, it becarre apparent that they had reached a fairly stable level of performance as indicated by the non-drugging trials graphs shown in With the pursuit rotor, the average of the tracking times obtained fran four trials each lasting for 50 seconds was plotted.
F.ach subject appeared to improve with time in his or her performance in the non-drug testing and for the m::>st part reached a level of performance that was sufficiently stable to warrant going on to the drug experiments. In the drug experim:mts, the initial testing or baseline values obtained before the secobarbital was administered, was fairly consistent with the majority of the test subjects, with their respective values obtained after two m:Jn.ths of non-drug testing further indicating that the ' test subjects had reached a consistent level of proficiency with the test equipn:Ellt.
After three drug trials on each individual, math test results at the one hour and three hour time intervals after secobarbital administration -were recorded and the results shown in the drug trial graphs in Figures   2-17. At the one hour time interval, subjects 1, 3, 4, 5 and 6 showed a drop in perfonnance during each drug trial; subjects 2 and 8 showed mixed perfonnances in that they improved during the first and third drug trials and deteriorated during the second; subject 7 improved her perfonnance during the first drug trial and decreased her perfonnance during drug trials ~ and three. At the three hour time interval after drug administration, subjects 1, 2, 3, 4, and 7 improved their perfonnance from the first hour test period; subject 5 showed a further decline in perf onnance during trials one and two and increased her perf onnance during drug trial three; subject 6 improved her perfonnance during trials one and ~ and showed no change in drug trial three; subject 8 improved his perf onnance during drug trial one and showed no change in drug trials two and three (Figures 2-17).
Pursuit rotor test results at the one hour and three hour tilre intervals were recorded and the results are also shown in drug trial graphs in Figures 2-17. At the one hotir tilre interval, subjects 1, 2, 3, 4, 5, 6, and 8 showed a decrease in perfonnance; subject 7 during the first ~ drug trials showed an increase in perfonnance and showed a decrease in perfonnance during the third drug trial. At the t.l-iree hour time interval after secobarbital administration, subjects 1, 2, 3, 6, and 8 showed an improvement in perfonnance fran the first hour during each drug trial; subject 4 improved in perfonnance during trial one and showed a continual decrease in perfonnance in drug trials two and three; subject 5 showed no change in perfonnance during drug trial one, a decrease in drug trial ~. and an increase in drug trial three; subject 7 showed a decrease in perfonnance during each drug trial (Figure 2-17).
Analysis of variance of the rrean scores obtained in both the math and pursuit rotor tests was based on the treat:rrEnts-by-treat:rrEnts-by- Math test results plotted from the no-drug tr~als and from drug trials 1, 2, and 3; 0-control; 1-first hour; 3-third hour.

Drug Trial #2
Pursuit rotor test results plotted from the no-drug trials and from drug trials 1, 2, and 3; 0-control; 1-first hour; 3-third hour.

Drug Trial #2
Math test results plotted from the no-drug trials and from drug trials 1, 2, and 3; 0-control; 1-first hour; 3-third hour.

Drug Trial 112
Pursuit rotor test results plotted from the no-drug trials and from drug trials 1, 2, and 3; 0-control; 1-first hour; 3-third hour. Math test results plotted from the no-drug trials and from drug trials 1, 2, and 3; 0-control; 1-first hour; 3-third hour. Pursuit rotor test results plotted from the no-drug trials and from drug trials 1, 2, and 3; a-control; 1-first hour; 3-third hour.

Drug Trial 112
Math test results plotted from the no-drug trials and from drug trials 1, 2, and 3; 0-control; 1-first hour; 3-third hour.

Drug Trial #2
Pursuit rotor test results plotted from the no-drug trials and from drug trials 1, 2, and 3; 0-control; 1-first hour; 3-third hour.

Drug Trial 112
Math test results plotted from the no-drug trials and from drug trials 1, 2, and 3; 0-control; 1-first hour; 3-third hour.

Drug Trial 112
Math test results plotted from the no-drug trials and from drug trials 1, 2, and 3; a-control; 1-first hour; 3-third hour.

Drug Trial #2
Pursuit rotor test results plotted from the no-drug trials and from drug trials 1, 2, and 3; 0-control; 1-first hour; 3-third hour. Math test results plotted from the no-drug trials and from drug trials 1, 2, and 3; 0-control; 1-first hour; 3-third hour. Pursuit rotor test results plotted from the no-drug trials and from drug trials 1, 2, and 3; 0-control; 1-first hour; 3-third hour. Analysis of the population ID3ans obtained at the zero tine, first hour, and third hour tine intervals in both the math and pursuit rotor tests were tested for significance (Table 1). The critical value of "t" was equal to 1.89 (df, 7) in all instances. With the math test, a significant negative change in perfonnance was detected in the group in drug trials two and three at the first hour after taking secobarbital.
(trn1 = 1.15, t:m2 = 2. 95, t;u 3 = 2. 38) . 1 Significant :improvement in math test perfonnance was shown from the first hour to the third hour. (t;u 1 = 2.86, t;u 2 = 2.34, ~3 = 3.09). 1 Pursuit rotor test results in each drug trial sho;ved a significant decrease in perfonnance at the first hour 1. Fm -experim:mtal F value obtained for math test in analysis of variance for drug trials 1, 2, and 3. Fpr -experim:mtal F value obtained for pursuit rotor test in analysis of variance for drug trials 1, 2, and 3. Sn1 2 3 -experimental dependent "t" values obtained for math test ' ' during drug trials 1, 2, and 3. ~rl 2 3 = experimental dependent "t" values obtained for pursuit ' ' rotor test during drug trials 1, 2, and 3. In drug trials one and three, significant :i.rrproverrent in perfonnance was shown be~en the first and third hour with the group return.ing to near baseline levels of perfonnance. (~rl = 2.27, ~r 3 = 2.59).1 In drug trial two, a significant decrerrent in psych011Dtor perfonnance persisted at the third hour after taking secobarbital. <~r 2 = 3.12). 1 The Speannan rank-order correlation test was perfonred on the data obtained in both the math and pursuit rotor tests at the first and third hours after dnJ8 administration and also on the data taken at the first hour alone. The percent change in perfonnance fran baseline for each subject was plotted against the blood secobarbital level found.
( Figures 18-21, Table 2). A positive percent change indicated a decre-m=nt in perfonnance and a negative percent change indicated an :i.rrproverrent in perfonnance. The critical "Z" value was 1. 96. With the math test, both the corrbined first and third hour data and the first hour data alone failed to show a significant relationship, the "Z" values being 1. 40 and 1.10 respectively. In the pursuit rotor test, both the ccrnbined first and third hour data and the first hour data alone showed significant rank order correlation in that their ''Z'' values were 3.31 and 2.59 respectively. This would indicate that a correlation existed between blood levels of secobarbital and the arrount of change in the test subjects' ability to coordinate observation and tmtor response as rreasured by the pursuit rotor.
Linear regression analysis perfoITIEd on the data as described for the Speannan rank-order correlation test showed similar results. (Figures 18-21). The math test data, the first and third hours corrbined and the first hour alone, failed to sh~v a significant linear cor-relation in that their regression coefficients, "r", were 0.246 and 0.248 respectively. The pursuit rotor test data however, showed significant linear correlation in both instances. The first and third hour regression coefficient was 0.432 and the first hour regression coefficient was 0.424. Critical values of "r" for both the math and pursuit rotor tests were 0.279 for the carbined data and 0.404 for the first hour alone. Lines of best fit were plotted in each case. Here again, regression analysis indicated that one could predict, on the average, the extent of impainrent in these test subjects of the coordination of observation and hand rrovement if the blood secobarbital level ~re knc:Mn.
Blood secobarbital levels for the eight test subjects ranged from 0.03 mgs.% to 0.30 mgs.% at the first hour after drug ingestion, and frcm 0. 02 mgs. % to 0. 20 rngs. % at the third hour after drug ingestion.
( Table 3). The obvious behaviorial effects of the secobarbital on the test subjects at the one hour ti.Ire period, based on personal observation of their actions and appearance, ranged from awake, mildly sedated, and competent to sedated, unsteady, and preferring sleep. At the third hour ti.Ire period, each subject in the test group appeared to return to norrral behavior and appearance even though blood levels of secobarbital remained relatively high.    Driving an autorrobile is a canplex process involving the acquisition of data concerning the surrounding envirornnent, the assimilation of this data, and the response by the driver to the situation at hand. Tb.is entire behavioral process sametines has to occur in milliseconds .
The psychological tests used for this experinEnt examined both a cognitive aspect of behavior and a rrotor response aspect of behavior. The sedative-hypnotic effects of a secobarbital are well known and docurrented (Sharpless, 1970). A therapeutic dose, 100 mgs. , is known to cause sedation, relief of anxiety, disinhibition, and the induction of sleep. Needless to say, this is not a condition conducive to the proper handling of an autarobile . Secobarbital in therapeutic doses has also been shown to effect sensory irechanisrns which could effect one's ability to drive an autorrobile. Holzman et al. (1975) showed that secobarbital disrupted srrooth-pursuit eye tracking perfonnance in five male subjects after a 100 mg.dose. A dose of 130 mgs. effected one individual's eye tracking perfonnance for up to 24 hours.
The secobarbital blood levels detected in the test group in this experinalt were consistent with therapeutic blood levels reported by Garriott (1974) and by Baselt et al. (1975)  This would create a situation which could better exmmne the effect of tlire on behavior mile tmder the influence of secobarbital. As has been done with alcohol, th::>usands of individuals will have to be examined using a variety of tests which dem::m.strate the effect of drugs on the many facets of human behavior which are relied upon when driving an autcm::>bile.
Only when this is done can responsible legislation be enacted with regard to the effects of secobarbital on driving an autorrnbile. When one reflects on all the investigative work that has been done concerning the effects of alcohol on human behavior and considers all the drugs that are ccmronly used by the driving public, it staggers the imagination to think what nrust be done before responsible legislation can be written concerning the effects of drugs on driving. It is hoped that this study will make a contribution to that end.

VI. SlM1ARY AND OONCLUSIONS
An investigation was made concerning the effects of secobaroital on skills used to drive an autorrobile. One hundred rngs. of secobaibital was administered to eight subjects and a psychaootor and cognitive aspect of their behavior was rreasured. The testing procedure consisted of a simple math test and a pursuit rotor test. Perfonnance in each of three drug trials was rreasured before drug administration and at one and three hours after drug achrinistration. Blood samples were taken before the one and three hour testing sessions.
A significant decrement in cognitive and psychamtor perfonnance was rreasured at one hour after drug ingestion. Only in the second drug trial did a psychanotor impairm=nt persist at the three hour tine period.
Pursuit rotor test results, as a neasure of psychcmntor function, showed a significant rank-order correlation to blood levels of secobarbital.
Percent impainnent at the one hour tine period and at the conbined one and three hour tine periods showed significant correlation to blood drug levels. A significant line of best fit could be drawn following linear regression analysis. Math test results as a neasure of cognitive function did not show rank-order correlation nor could a significant line of best fit be drawn between drug levels and percent impainrent.
Tine, as well as blood secobarbital level, appeared to be an important factor when behavior impai.nrent is to be measured. Impainrent in both cognitive and psychamtor function was noted at the one hour tine period but not at the three hour tirre period even though secobarbital blood levels remained in the therapeutic range. Further investigation of this observation is warranted.