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Chronic Cannabis Use in Costa Rica: A Description of Research Objectives PDF Print E-mail
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Books - Cannabis and Culture
Written by W.E. Carter   


A report on the initial stages of research on chronic cannabis users in Costa Rica. Work on the project began in July, 1973, and is expected to terminate by September, 1975. It will involve in-depth studies of the sociocultural context of cannabis use, pulmonary and visual function studies, neuropsychological studies, and basic bio-medical measurements. The format of the research will be explained in detail and pre-liminary findings discussed. Critical evaluation of the project's design will be welcomed.

In July of 1973, a two year study began on the effect of long-term cannabis use irf Costa Rica. Sponsored and funded by the National Institute for Mental Health, the study is being coordinated by the University of Florida and facilitated by both the Costa Rican Ministry of Health and the Social Security Hospital (Hospital Méjico) of San José.

The goal of the research is to obtain in-depth material on the socio-cultural context of long-term cannabis use, the effect of such use on inter-personal relations, job performance, motivation, aspirations, career development, and on the biology and psychology of the human organism. No studies are planned on acute effects. Rather, a final sample of approx-imately 40 heavy,1 chronic users and 40 carefully matched non-users, will be selected and will be subjected to prolonged, controlled testing and observation in both the sociocultural and biomedical fields to mea-sure the effects of chronic use. To facilitate close matching, initial work will encompass 240 individuals, 80 of whom will be long-term users, and 160 non-users.

Many ask why such a study should be carried out in Costa Rica. Perhaps the best answer is that, to date, no studies have been made of chronic cannabis use in any part of Latin America (if one excludes Ja-maica from that geographical category), and that, during a feasibility study made in three Latin American countries, it was found that the Costa Rican health authorities were the most willing of all to host and support such research. During the past 10 years, cannabis use has spread rapidly through the middle and upper sectors of Costa Rican society, especially among the youth. Conservative estimates are that at least 25% of all university students use the drug, and that its use has become com-mon in junior and senior high schools as well. This rapid diffusion of what was formerly a lower-class trait has greatly concerned Costa Rican authorities and has made them anxious to learn as much as they can both about use in their country and about possible implications for perfor-mance and health.

The sanitary code of Costa Rica specifies that all research on drugs be coordinated through the Ministry of Health and requires police and other law enforcement authorities to offer their full cooperation for such research. With the support of the Ministry, legal guarantees have been obtained for each of the researchers and subjects. Prosecution for canna-bis production, sale, and possession continues unabated, however. This situation makes research a delicate matter.

Because of widespread police harassment, selection of both the experi-mental and control groups must be done with great care. To accomplish this, three social anthropologists are working in Costa Rica, gaining initial entry, establishing confidence by looking at non-threatening areas such as socialization of the young, and gradually establishing rapport through the technique of participant observation. These procedures are beginning to provide much contextual material on subject areas such as family, community, associations, and values. These areas are not irrelevant. Without them a full understanding of the function and meaning of cannabis in Costa Rican society will be impossible.

Fifteen months will be devoted to participant observation and inter-vievving in the natural context of communities and occupational groups. During this period of time, the anthropologists will concentrate on several basic objectives:

1. The collection of data as complete as possible on community life, pattems of interaction, life-crisis rituals, work patterns, daily, weekly and yearly cycles, religious symbols and rituals, economic life, and interaction with neighboring communities, social groups, and work groups.

2. General life history data for all individuals forming part of the original sample of 240, and in-depth life histories for those selected in the final sample of 80.

3. Genealogical studies of the final sample of 80.

4. The form and context of cannabis use, initiation of the user, self perception of the effect of cannabis, perception of the effect on the part of relatives and associates of the user, function of use, frequency, and dosage.

5. Collection of cannabis samples for laboratory analysis on a bi-monthly basis, in the form in which the drug is commonly consumed.

6. Analysis of market networks, with special emphasis on the role of cannabis in economic exchange. The impact that cannabis purchase makes on family bud-gets will be given special study, inasmuch as it may be associated with poorer nutrition, clothing, education, or housing for the entire family.

7. In-depth information on family interaction for those 80 individuals con-stituting the final sample.

8. Controlled comparison of interactional patterns of chronic users with those of carefully matched non-users.

One hypothesis of special interest to the anthropologists is that prolonged cannabis use may be associated with the a-motivational syndrome. Selection of only those cannabis users who are productive and successful could skew the sample by eliminating these who are at the lowest margin of society. In working with life history materials, the anthropologists will search for any contrasts which may exist between the subject and control group in terms of career ambitions as these change over the years. They will algo collect information on the way a subject's family, friends, and employers perceive the effect of cannabis on his behavior and aspirations.

Because health, and therefore work habits and ambition, may be so directly affected by diet, during the second year of the research, nutritional studies are planned for all those forming part of the final sample. From the family of each subject and each control, data will be collected for four consecutive days. A daily register of foodstuffs will be compiled, using a combination of direct weighing and measurement of foods in the form in which they are consumed, and supplementing these measurements with information given by the housewife or maid responsible for preparing foods. Controlled comparison will then be made of nutritional patterns in the homes of chronic users and non-users.

Once an initial core of subjects and controls has been identified by the anthropologists, the physicians and psychologists attached to the team will begin medical, biological, and psychological studies. These will focus on the aspects of organ function which are of most concern as possible targets for the harmful effects of chronic cannabis use. The preliminary sample of all male, long-term cannabis users and 160 controls will re-ceive a complete medical history and physical examination. The history will contain questions concerning tobacco, alcohol and other drug use, but will specifically omit questions concerning cannabis use. A medical-mental status and neurological examination will be included in this screening procedure. Finally, a battery of laboratory tests will be per-formed. These will include :

1. Blood count (hematocrit, hemoglobin, white blood cell count and differen-tial, red blood cell count and red cell indices).
2. Erthrocyte sedimentation rate.
3. Urinalysis (pH, sugar, protein, acetone and specific gravity).
4. Stool — ova, parasite and occult blood.
5. Serological test for syphilis.
6. Two-hour post-prandial blood sugar after injection of 75 gms. of glucose.
7. Blood urea nitrogen.
8. Prothrombin time.
9. Alkaline phosphatase.
10. Serum bilirubin, direct and total.
11. SGOT and SGPT.
12. Serum protein electrophoresis.

Two of the objective and best documented effects of cannabis use are the enlargement of scleral blood vessels and the mild decrease of intra-ocular pressure. Subjective effects and color awareness are frequently reported, and pupil size has been reported to be both larger and smaller than normal in studies of the immediate effects of marihuana ingested by smoking. To better understand the effects of cannabis on vision, each individual in the original 240 sample will be given a routine test of visual acuity, refraction, slit lamp examination, applanation tonometry, routine funduscopic examination, and a test of color vision using Ishihara plates.

In setting up the final study group of 40 long-term cannabis users and 40 controls, subjects with chronic illness which can be attributed to causes other than cannabis will be excluded. Examples of such subjects will be those with tuberculosis, syphilis, alcoholism, severe infestation with intestinal parasites, or major visual abnormalities. Subjects with relatively minor illnesses or static deficits to which they have compensated well, such as old stable orthopedic deformities without serious locomotor impairment or work handicap, will not necessarily be excluded.

Since there has long been concern about the possible harm to brain function caused by cannabis, special care will be given to an evaluation of those areas measuring some aspect of brain function. Each individual in the original 240 sample will be given a standard "mental status examina-tion" which neurologists and psychologists customarily perform. Individ-uals with neurological deficits which can be ascribed to other disease processes will be eliminated from the study.

The 80 individuals selected for the final sample, 40 of whom will be chronic cannabis users and 40 non-users, will be subjected to a series of special studies. These will focus on (1) visual function, and neurological response, (2) pulmonary function, (3) sleep electroencepholographic patterns.

The effect of chronic, heavy cannabis use on sight will be probed through a variety of tests, including :

1. Facility for dark adaptation, using the Goldman Weekers adaptometer. This measure gives information about the rate and extent of dark adaptation and the time at which the shift from the photopic to the schotopic system takes place. It is intended to test peripheral visual function.
2. Acuity, using two techniques.
a. Static visual acuity stressed by variation in illumination. Since functional acuity is related to illumination level, stepwise reduction in illumination may differentiate those subjects with sub-clinical impairment.
b. Dynamic acuity, using a target moving at standard rates across a field. Measure would be of the visual angular subtense of groups of letters moving across a field at varying rates. Previous studies indicate that hypoxic stress, for example, can be discriminated by this test.
3. Color balance, using an anomaloscope. The instrument presents a standard color with known hue and saturation. A variable spectral color is provided and the subject is instructed to make a match between this and the standard. The hue and saturation required for the match are an accurately established measure of color, balance and preception.
4. Pupillary response to stepwise reductions in light level, using the Goldman instrumént with the addition of an infrared screening television camera and monitor to produce an image on the television screen enlarged sufficiently for photographing with Polaroid equipment for later measurement of pupillary size.

Measurement of the effect of cannabis use on pulmonary function will include the following :

1. Vital capacity.
2. Timed forced expiratory volume.
3. Maximum breathing capacity.
4. Arterial pH, po and pCO2.
5. Diffusing capacity (CO).
6. Maximum mid-expiratory flow rate.
7. Lung closing volume.

Sleep electroencephalography has demonstrated characteristic shifts in sleep level patterns caused by certain hypnotics and tranquilizers as well as by certain psychiatric disturbances. Previous studies have shown suggestive changes in sleep EEG patterns of short-term cannabis users, but no detailed studies of long-term users have been reported. The sleep EEG may itself serve as a bioassay method for pharmocologic compounds having CNS effects. Because of the many external stimuli which affect sleep patterns in normal man, assessment of changes which can be attri-buted to a drug effect require control of external stimuli and familiariza-tion of the subjects with the experimental setting. For this reason, each of the chronic users and the matched controls will have eight consecutive nights of EEG recording as outpatients at the Hospital Méjico. The resulting data will be subjected to both visual scanning and computer analysis and will be interfaced with the social, behavioral and other medical data on the sample population.

Supplementing the insights coming from the sleep EEG's will be a battery of neuropsychological tests, designed to detect early evidence of brain damage. Seven of the tests will be essentially culture-free to the extent that they will require a minimum of linguistic or verbal instruction for understanding and response. These will primarily assess attentional, motor and/or somesthetic skills. All seven tests have been widely used in the assessment of brain functions in humans. Five tests will be specifically addressed to delayed memory retrieval (verbal and non-verbal) and intellectual cognitive skills.

All tests will be standardized on a separate subject sample in Costa Rica in the pre-test phase in order to reduce cultural sources of variation or error variance in performance. A tentative selection of these tests has been made contingent upon subsequent developments in Costa Rica. It includes the following:

1. Culture Fair Intelligence Test.2

The Culture Fair Intelligence Test, developed by Raymond 13. Cattell for use with children and adults, was designed as a measure of general intelligence. In an attempt to make the instrument "culture fair" (i.e. minimally contaminated by differences in culture patterns of motivation, achievement, social status, etc.), Cattell employed nonsense material, presumably universally unfamiliar, as well as some common place material. The test, while heavily concentrated on per-ception, taps categories such as progressions, analogies and abstract reasoning. A visual mode of stimulus presentation is used with a multiple choice response mode. In general, the major reviews of the instrument raise some doubt as to its universal applicability. However, it has come closer to meeting such standards than any other test which has attempted to cut across cultures. Furthermore, it does appear to be a reasonably good measure of general intelligence. In lieu of a test designed specifically to measure general intelligence within a particular cul-ture, Cattell's test would appear to be an appropriate instrument to employ. Split-half and test-retest reliability coefficients exceed 80 in most samples, and the vitality coefficients exceed 80 in most samples, and the vitality coefficients (i.e. as a rneasure of general intelligence) have ranged from .56 to .85 with the Stanford-Binet, .73 with the Otis Group Intelligence Test, and .84 with the Wechsler-Bellevue.

2. Finger Oscillation Test.3

This test constitutes a measure of fine manual ability. The subject is required to depress rapidly a key for 10 seconds using his index finger. A Veeder-Root counter records the frequency with which the key is depressed during the time interval. Four 10-second trials per hand are administered. Scores are summed and averaged over trials for each hand. Difference scores between hands are used to determine the degree of manual laterality.4

3. Small Parts Manual Dexterity Test.5

This test measures the more refined aspects of motor ability, involving a precise coordination of finger and hand movements, as well as control of arm movements. The subject is required to use a tweezer to pick up small pins, place them in holes, pick up small metal collars and place them over the pins. Scores are computed on the number of pins that are inserted and capped during a three-minute inter-val with each hand. The subject starts with his preferred hand and is allowed to practice before the timed trial begins. The difference score between hands is also used to compute the degree of manual laterality.°

4. Halstead Tactual Performance Test.7

This task, as modified and administered in the Satz Neuropsychology Laborato-ry at the University of Florida, is designed to test unilateral tactile learning and central nervous system integrity. It provides a direct measure of the presence or absence of transfer capabilities from the dominant to the nondominant cerebral hemisphere. By eliminating all visual and auditory cues, the patient is required to pick up a specified number of wooden geometric shapes and place them in a formboard in a 15-second interval, using first the preferred hand and then the non-preferred hand. Evidence of the transfer of learning from the dominant cere-bral hemisphere to the nondominant cerebral hemisphere is demonstrated by a significant reduction in the time required to perform the task with the non-preferred hand.

5. Finger Localization Test.°

This task is composed of three parts which combined measure the subject's ability to integrate and report sensory stimulation. Part I measures unilateral and bilateral differentiation between digits which should be complete in the ab-sence of cortical dysfunction. The fingers of each hand are numbered one through five, beginning with the thumb: stimulation by touching the finger in question with the tip of a pen or pencil, out of the subject's range of vision, is reported by number. Part II requires the subject to identify the finger stimulated by pointing to the same finger represented on a diagram of each hand, Part III requires the subject to identify a letter of the alphabet which is traced on his finger tip. Scores are reported in terms of errors on each part of the task and are combined for total errors in terms of right and left sides.

6. Satz Block Rotation Test.9

This is a general screening exam for cortical dysfunction. In Part I the subject is required to rotate designs using a stimulus design composed of two to four red and white blocks. The orientation of the stimulus design is always horizontal and vertical, with the required rotation being a 90 degree turn to the left and to the right. Part I is composed of 16 trials, with the first trial used for demonstra-tion, so that only 15 trials are scored. Part II is composed of one demonstration trial and 7 test trials which are scored. In Part II the stimulus design is always presented at a 45 degree angle to the subject, so that the subject must perform a 90 degree rotation from the 45 degree presentation, both to the left and to the right. Errors are recorded in terms of general, angulation, duplication and time (each trial has a 65 second time limit). These are computed with the subject's age and performance IQ to render a multivariate Z score which demonstrates the presence or absence of cortical dysfunction (Discriminant Function Analysis).

7. Raven's Progressive Matrices."

The task consists of designs which the subject is required to complete using multiple choice options of the design part which best fits. No verbal responses are required. Answers may (1) complete a pattern, (2) complete an analogy, (3) systematically alter a pattern, (4) introduce systematic permutations, or (5) sys-tematically resolve figures into parts. Scores are reported in terms of the number of items correctly solved and may be converted to percentile ranks.

8. Facial Recognition Memory Test (University of Florida modified version, 1971) .

The subject is presented with 12 photographs of unfamiliar men and women, which he is asked to study for 45 seconds. At the end of this time period, the photograph is removed and an interpolative task of approximately one and one-half minutes is presented. The subject is then presented with a photograph of 25 pictures of unfamiliar men and women and asked to identify the 12 which appeared in the first photograph. This is a measure of non-verbal memory (short term). Scores are reported in terms of number of photos correctly identified.

9. Verbal Memory Task.

This will be an analog of the Wechsler Memory Scale,ll as modified and ad-ministered in the Satz Neuropsychology Lab. Two short paragraphs of a narra-tive nature will be devised by the consulting psychologist in San Jose using material that is culturally homogeneous for the population to be examined. The subject will hear the paragraphs (one at a time) in colloquial Spanish and will be asked to relate to the examiner the content of the passage immediately upon hear-ing it for the first time. Scores will be based on the number of phrases correctly remembered or approximated for each of the two paragraphs. After a 90-minute delay, the subject will again be asked to repeat to the examiner the content of the two paragraphs which he heard earlier. Thus, two scores will be obtained: one for immediate short-term verbal memory and one for delayed short-term mem-mory.

10. Visual Reaction Times.12

The aim of this task is to measure the duration of attention on the part of the subject. He is required to press a button as soon as a neon lamp in front of him is switched on. A trial period of 10 stimuli will be given, during which the subject will be urged to press the button as rapidly as possible. No further encourage-ment will be given in the course of the test. The task itself consists of 50 consecu-tive stimuli presented at irregular intervals, varying between 2 and 5 seconds, without a preceding warning signal. The subject's time until response will be recorded by means of a 1 /100 second chronograph, summating automatically the values of the answers. The mean of the 50 trials will denote the reaction time of the subject.

11. Continuous Choice Reaction."

This task is also aimed at measuring the subject's vigilance. He is instructed to press a button, which is held in the subject's hand, each time one particular combination of designs appears on the projection screen in front of him. He is instructed to make no response to any other combinations of designs which are projected. A total of 500 combinations will be presented to the subject, with 170 possibilities for a correct response. There is a 1.5 second time interval between each projection. An error is recorded when the subject presses the button for an incorrect combination but fails to do so within the 1.5 second inter-trial interval. The score for each subject consists of the sum of errors and omissions.

Biomedical and psychological studies, as described above, will not begin for several more months. Data gathering by the social anthropologists has just begun. The first few weeks in the field have produced only superficial impressions on cannabis use in Costa Rica. They have, however, suggested a series of fascinating questions.

There seems little doubt that cannabis is widely diffused in the country. It seems to have begun as a lower class phenomenon and quite recently spread into the rest of society. Costa Rica seems to be a major source for distribution throughout the Western hemisphere, and the obtaining of detailed information on the productive and distributional systems seems well within the realm of possibility. Informants report an enormous variance in potency among different types of marihuana peddled on the streets of San Jose. Families of users are often divided, with some individ-uals abstaining and others using the drug heavily over a long period of time. Even among users, there seems to be no universal pattern. Some use cannabis only during their leisure hours ; others for selected work tasks, while still others use it any time it becomes available.

In many ways the Costa Rican situation parallels that found in the U.S. more closely than does that reported from the recent Jamaican study. Cannabis is actively suppressed in Costa Rica today, and the price of the commodity fluctuates wildly in response to the degree of oppression. While the drug is widely diffused, this diffusion still seems to be limited to a minority of the population.

To be successful, the project must overcome continuous obstacles. If it succeeds, it promises to give us important additional insight into the effects of long-term heavy use on sociocultural, biological, and psycholog-ical development. Such insight would be a significant step forward.

Contract No. HSM-42-73-233 (ND).

1 Heavy use is being defined as daily use, and chronic use as continuous use over at least a 10-year period.

2 R. B. Cattell, Theory of fluid and crystallized intelligence: a critical experiment. Journal of Educational Psychology. 1963. 54:1-22.; R. B. Cattell, Abilities, their structure, growth, and action. New York: Houghton-Miffin, 1971.

3 R. M. Reitan, Certain differential effects of lateralized brain lesions' on the Trial-Making Test. Journal of Nervous and Mental Disorders. 1959. 129:257-262.

4 P. Satz, K. Achenbach, and E. Fennell, Correlations between assessed manual laterality and predicted speech laterality in a normal population. Neuropsychologia, 1967,5:295-310.

5 J. E. Crawford, and D. M. Crawford, Small Parts Dexterity Test. 1959. New York : The Psychological Corporation.

6 Satz, et aL, 1967.

7 R. M. Reitan, Manual for administration of neuropsychological test batteries for adults and children. 1964. Indianapolis, Neuropsychological Laboratory, Indiana University Medical Center.

8 A. L. Benton, Development of finger localization capacity in school children. Child Development, 1956. 225-230.

9 P. Satz, A block rotation task: the application of multivariate and decision theory analysis for the prediction of organic brain disorder. Psychological Mono-graphs. 1966. 80(21):1-29.

10 J. C. Raven, Progressive matrices. 1960. New York: The Psychological Corporation.

11 J. Wechsler, Wechsler Memory Scale. 1945. New York: The Psychological Corporation.

12 E. De Renzi, and P. Faglioni, The comparative efficiency of intelligence and vigilance tests in detecting hemispheric damage. Cortex, 1965. 1(4): 410-433.

13 Ibid., 1965.


Our valuable member W.E. Carter has been with us since Tuesday, 21 February 2012.