Bromazepam

The present study consists of two parts. In the first part 23 polydrug abusers and a control group of 33 from United Arab Emirates were tested for visuographic functions using the Benton Visual Retention Test. In the second part 14 polydrug abusers and a group control subjects were tested for sustained attention and reaction time. Analysis suggested that polydrug use affects visuographic function and sustained attention adversely but has no effect on reaction time. The later result was explained in terms of indiscriminate responses by substance abusers.

The present study is a part of multidimensional research project supported by the UAE government. The aim of the research project was to investigate social, legal, medical, psychiatric and psychological aspects of substance abuse in UAE to establish findings which can form the basis for a national policy towards substance abuse in the country. The aim of the present study was to investigate the effect of substance abuse on some cognitive functions of substance abusers, namely attention, visuographic function, and reaction time in UAE.

Several studies have reported findings concerning the effect of substance abuse on cognitive functions. Miller (1985), for example, has reviewed the literature on neuropsychological assessment of substance abusers and demonstrated the presence in chronic abusers of neuropsychological impairment of the central nervous system (CNS) caused by depressants including alcohol and opiates, especially when combined in a polydrug pattern of abuse. Also, Fals-Stewart (1993) reported that substance abusers who have longer substance abuse histories performed more poorly than younger substance abusers who have shorter substance abuse histories. In three studies Grant, and Grant and associates have investigated the effect of polydrug abuse on neuropsychological deficits. Grant, Mohns, Miller and Reitan (1976) reported that, in some individuals, heavy drug abuse may be associated with neuropsychological dysfunction, which persists an average of two months beyond cessation of the drug use. In another study, Grant, Adams, Carlin, and Rennick (1977) reported that neuropsychological deficit was associated with extensive and intensive use of sedatives and opiates. Also Grant, Adams, Carlin, Rennick, Judd, and Schooff (1978), who administered the Halstead-Reitan Neuropsychological Test Battery to a group of polydrug users, a group of psychiatric patients, and a group of control subjects, found that impairment in test performance in polydrug users was related to extensive use of CNS depressants and opiates. The effect of cannabis on cognitive functions was investigated by Leon-Carrion (1990) who administered Wechsler Adult Intelligence Scale (WAIS) to 23 cannabis users and an equal number of control subjects, and reported significantly inferior performance for cannabis users. The performance of hashish users on vigilance, or sustained attention tasks, was investigated by Bahri and Amir (1994) who tested a group of hashish users and a group of control subjects in Algeria on a vigilance task. They reported inferior performance on the vigilance task for hashish users when compared with nonusers. The effect of yet another drug on vigilance tasks was investigated by van Leeuwen, Verbaten, Koelega, Kenemans, and Slangen (1992), who studied performance on a vigilance task under the influence of bromazepam and reported that the drug did not aggravate the normally-occurring decrement in performance, but had an effect on overall performance: accuracy reduced but speed improved. The effect of inhalants on cognitive functions was studied by Korman, Mathews, and Lovit (1981) who reported that inhalant abusers performed more poorly than other drugs abusers on a neuropsychological battery which tapped global as well as specific functioning, suggesting that the effect of inhalant abuse may be severe and widespread. The performance of substance abusers on visuographic function tests, attention and concentration tasks was investigated by Pakesch, Loimer, Grunberger, Phersmann, Linzmayer, and Mayerhofer (1992), who compared the performance of a group of HIV- 1 infected substance abusers, a group of HIV-1 negative substance abusers, and a group of healthy volunteers. They reported that the performance on the Benton Revised Visual Retention Test, which was used as a measure of organicity, showed significant reduction in the number of correct answers, and a significant increase in errors in the substance abusing groups compared with the control group. No significant difference in attention among the three groups was found. They also reported no significant difference in concentration between normals and HIV1 negative substance abusers. The visuographic function of substance abusers was studied also by Amir and Babri (1994) who administered the same test to a group of heroin, alcohol and polydrug abusers, and to a comparable group of nonusers in Saudi Arabia's Eastern Region. They reported that substance abusers reproduced significantly fewer correct designs and made more errors.

The relationship of substance abuse to attention deficit is not a simple one. While there is evidence that prolonged substance abuse has an adverse effect on attention, there is also evidence that attention disorder contributes to earlier onset of substance abuse. Tarter, Mezzich, Hsieh and Parks (1995), for example, reported that subjects who qualify for a diagnosis of Psychoactive Substance Use Disorder (PSUD) were impaired on cognitive tests measuring attention, verbal intelligence, perceptual efficiency, language competence and educational achievement. On the other hand, Horner and Scheibe (1997) reported that subjects exhibiting attention deficit hyperactivity disorder (ADHD) began drug use at an earlier age, had more severe substance abuse, and had a more negative self-image prior to drug use and improved self-image with drug use. Their results support substantial comorbidity of ADHD among adolescent substance abusers, with indications of drug use for self medication. Comings (1997) argued for a common genetic factor underlying both attentional disorder and substance abuse, and stated that many childhood and adolescent disruptive behaviors, including attention deficit and substance abuse, are part of a spectrum of interrelated behaviors which have a strong genetic component, that they are polygenetically inherited, share a number of genes in common which affect dopamine, serotonin, and other neurotransmitters, and are transmitted from both parents.

In the first part of the present study a group of polydrug abusers will be compared with a control group for visuographic function. In the second part another group of substance abusers will be compared with a control group for attention and reaction time.

PART 1: VISUOGRAPHIC FUNCTION

METHOD

SUBJECTS

Fifty six male subjects were included in this study. Twenty three were hospitalized substance abusers whose ages ranged between 20 and 37 years with mean of 29.8 years (+/- 4.3). Subjects with histories of head injury, electroconvulsive therapy, major physical or mental illness liable to affect cerebral functioning were excluded. Those who were medicated at the time of the testing also were excluded. Subjects in this group abused hashish, heroin and alcohol regularly. The duration of substance abuse for this group ranged from 8 months to 16 years (mean of 7.9, SD: 4.35). Control subjects were 33 men with ages ranging between 23 and 45 years (mean 29.2, SD: 6.8). Criteria for exclusion from this group were history of drug abuse, head injury, electroconvulsive therapy, and mental or physical illness liable to affect cerebral functioning.

MATERIAL

The Benton Revised Visual Retention Test was given (Benton, 1974). Researchers have shown that this test can successfully discriminate between control and brain injured individuals. (Sterne, 1969; Brewer & Perrett, 1971, Marsh & Hirsch, 1982). The version used was Form C, Administration A in which designs are reproduced immediately after 10 second exposure. Both Numbers correct and Errors were calculated for each subject.

PROCEDURE

The Benton Revised Visual Retention Test was administered to both control subjects and substance abusers. It was administered to subjects in the latter group only when the ward physician judged that each individual's detoxification process had been completed.

RESULTS

A t test showed that the two groups, drug abusers and control subjects, were significantly different. Substance abusers reproduced significantly fewer correct designs and made significantly more errors than control subjects (Table 1).

PART 2: SUSTAINED ATTENTION AND REACTION TIME

METHOD

SUBJECTS

Twenty eight subjects, all males, were tested on sustained attention and reaction time tasks. Fourteen were drug users held in Al Ain prison in UAE. Subjects included in this group were substance abusers who had been under arrest for at least three months for using prohibited substances, and were awaiting either trial or transportation to a special prison facility. They were polydrug abusers who used heroin, hashish, and alcohol regularly. The duration of substance abuse for this group ranged between 2 to 13 years with mean of 8.4 years (+/-8.0). Subjects had had no access to drugs for the preceding three months and were not under any medication. Their ages ranged between 23 and 30 years (mean of 25.6 years, SD: 1.9). A control group of 14 men was also included. The ages of the subjects in the control group ranged between 17 and 27 years (mean of 23.5 years, SD: 2.5). Control subjects were not taking medications which might have affected their performance.

APPARATUS

An IBM personal computer and a computer program written for the assessment of sustained attention were used. The computer program used was "Vil", a version of the Continuous Performance Test which is used to assess sustained attention and is useful in diagnosing brain damage. (Rosvolt, Mirsky, Sarason, Bransome and Beck, 1956; ForThought Ltd., 1993).

PROCEDURE

Subjects were tested on a task in which a stimulus appears on a computer monitor somewhere within a triangle. A 'target' occurs when the stimulus appears in the upper part of the triangle. The subjects are instructed to respond as quickly as possible by pressing the space bar whenever they detect a 'target' . Targets occurred randomly with a probability of 0.2. Prior to the main task subjects were given a 1minute practice session. They were also given feedback about their performance during the practice session, and were instructed to maximize 'hits' and minimize `false alarms'. Both reaction time and 'A', a measure of the subject's sensitivity in the detection task, were measured.

RESULTS

The statistical analysis of the subjects' mean sensitivity in the detection task using t test showed significant differences between substance abusers and control subjects, with nonabusers scoring better, while reaction time analysis showed no significant difference between the two groups (Table 2).

DISCUSSION

The scores of substance abusers and nonabusers showed a distinct tendency for substance abusers to score worse on the visuographic function test indicating impaired visuographic function. Both test measures, number of correct designs and number of errors were consistent in reflecting the impairment of visuographic functions in substance abusers. This is consistent with a previous report by Pakesch et. al., (1992) who reported inferior performance by substance abusers on the Benton Revised Visual Retention Test, and is consistent also with a report by Amir and Bahri (1994) who administered the same test to a group of substance abusers and a group of nonusers in Saudi Arabia's Eastern Region and reported lower performance by users.

The performance of subjects indicates that drugs have an adverse effect on sustained attention. The present results have shown that drug taking affected negatively the subjects' performance on the detection task but not their reaction time. Similar results were reported by van Leeuwen et. al., (1992) who found that the performance of subjects under bromazepam was characterized by reduced accuracy and improved speed. Such phenomena could be explained by the fact that drug users pressed the response key indiscriminately to increase their detection rates. But this liberal behavior led not only to greater detection rate and shorter reaction time but have also caused higher rates of false alarms. Similar results have been reported in earlier studies. For example Davies and Parasuraman ( 1982) concluded that "an observer who is unable to detect signals can nevertheless achieve an extremely high detection rate if he always responds positively; of course he will then also make a number of false alarms" (p. 38). This will not lead to a higher score on sensitivity because, as hit rate increases, false alarm rate also increases, but will lead to shorter reaction time. Therefore reaction times noted here were not conclusive. Further studies are needed to ascertain whether there is really no difference between drug users and nonusers in reaction time, or whether it was the indiscriminate pressing of the response key by drug users which caused the findings of no difference between the two groups.

The findings of the present study indicate that polydrug abuse has an adverse effect on both sustained attention and visuographic function; and that the effect of substance abuse on attention persists three months beyond cessation of the substance use.

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TAHA AMIR AND TOUFIK BAHRI

UAE University, United Arab Emirates

Dr Taha Amir, Chairman, Department of Psychology, and Toufik Bahri, Department of Psychology, United Arab Emirates University.

This research was supported by the General Directorate of Security Affairs, Drug Enforcement Administration, Ministry of Interior, United Arab Emirates. Key words:

Please address correspondence and reprint requests to Taha Amir, P.O. Box 17851, Al Ain, United Arab Emirates.

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