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Marihuana, A Signal of Misunderstanding - Table of Contents

The Report of the National Commission on Marihuana and Drug Abuse

Effects of Long-Term Cannabis Use


Permanent congestion of the transverse ciliary vessels of the eye and accompanying yellow discoloration is the only physical effect firmly linked to long-term marihuana use (Ames, 1958; Chopra, and Chopra, 1957; Dhunjibhoy, 1928). Although there are several suspected or reported effects, none has been conclusively demonstrated in a valid study. Some (Chopra and Chopra, 1939; Indian Hemp, 1893) claim that bronchitis, asthma and other respiratory problems may be produced by chronic and excessive use of potent compounds in India. Eastern smoking, preparations are often a mixture of tobacco and hashish.

Indian users reportedly exhibit digestive tract abnormalities, weight loss and disturbed sleep (Chopra and Chopra, 1939; Soueif, 1967). However, the contributing factors of poor living conditions, malnutrition and prevalence of communicable disease could not easily be separated.

A high percentage of heavy Moroccan users have developed obliterative arteritis of the lower extremities (Sterne, 1960) possibly related to the occurrence of tropic foot ulcers (Ganja -foot) (Miras, 1965). The progression of this abnormality is claimed to parallel prolonged use of the drugs.

Mendelson et al. (1972) were unable to demonstrate clinically significant abnormalities in the extensive battery of tests performed which could be attributed purely to the subjects long-term use of marihuana. No histories were obtained of neurological, hepatic, renal, pulmonary, cardiac, gastrointestinal, (renitourinary, or nutritional disorders. No history of psychotic illness was given.

All subjects were Judged to be in normal mental, health by psychiatric interview and psychological tests (MMPI and Edwards Personality Preference Inventory). Three subjects were felt to be neurotic.

Pre-drug complete physical exams, chest X-ray, electrocardiogram, urinalysis, complete blood count and blood chemistry profile did not demonstrate, any clinically significant abnormalities. No subject showed evidence of poor nutrition.

Pulmonary vital capacity and one second forced expiratory volume were reduced in 12 of the 20 subjects initially. These changes were not correlated with either current cigarette smoking or f requency or duration of marihuana smoking. Histories of past cigarette use, past patterns of marihuana use and past or present contact with environmental air pollutants were inadequate to attempt to account for these pulmonary findings.

Many of the subjects were in fair to poor physical condition as judged by a cardiac exercise tolerance test.

Four of the 20 subjects' initial performance on a battery of cognitive functions tests was poorer than would have been predicted by high average to superior I.Q. scores and educational backgrounds. One of the casual subjects demonstrated improvement with retesting consistent with good brain function. Thus, behavioral impairment was present in three subjects.

Whether the impairment is related to prior drug histories, particularly the excessive use of LSD by the two heavy users, cannot be ascertained. For the casual users, nothing in the case histories possibly elucidated the reason for relatively poor performance based on the exceptionally high I.Q., 139 and 128.

Many Western investigators have suggested that smoking hashish or marihuana may possibly cause bronchitis, asthma or rhinopharyngitis (Bloomquist, 1967; Waldman, 1970; Tylden and Wild, 1967; Schwartz, 1969).

Tenant et al. (1971) described bronchitis, sinusitis, asthma and rhinopharyngitis in 22 American soldiers in Germany who smoked daily enormous quantities (100 grams or more) of hashish for six to 15 months. These conditions, believed to be caused by irritation of the respiratory tract by hashish smoke, seemed to improve, with diminished hashish use.

Twenty-one of the subjects were tobacco cigarette, smokers and occasionally smoked hashish rolled in a tobacco cigarette. Nine patients had symptomatic bronchitis. Five of these subjects underwent pulmonary function tests while consuming their usual daily amount of hashish and again three days after discontinuing use. A mild obstructive pulmonary deficit was demonstrated which was at least partially corrected with diminished hashish intake. Hashish contributed to rbinopharyngitis in 12 of the patients and this effect was not allergic in origin. Urticaria, acne, diarrhea and gastrointestinal cramps were less frequent complaints. Extensive hemotological and hentochemical studies including liver function tests were performed and were within normal limits.

Mann et a]. (1970, 1971) and Finley (1971) studied the effect of marihuana smoking on the pulmonary function of eight non-cigarette smoking marihuana smokers (20-27 years old). Marihuana smoking history was defined in marihuana cigarette-years, that is, one marihuana cigarette daily for one year or the equivalent over a longer or shorter period. The mean marihuana cigarette years for the group was 11 and the range from 2.5 to 26. Three of the marihuana users also used hashish. Chest X-ray, comprehensive spironietry deterinitiations, lung volumes and carbon monoxide diffusion studies were observed and retested with prednisone. Pulmonary functions were essentially normal for all of the non-cigarette smoking marihuana smokers and non-smoking controls.

These investigators were able to distinguish differences in quantity and structure and function in pulmonary macrophages and minor material between marihuana smokers and nonsmokers. In tobacco smokers more marked changes were noted. These changes do not indicate a diminution in defensive capacity of these cells.

Kew et al. (1969) has suggested a possible hepatotoxic effect of marihuana. right persons who smoked marihuana for two to eight years, at least six times a week, evidenced mild liver dysfunction by liver function tests and liver biopsy. Several of the patients admitted to the use of alcohol and oral amphetamines but denied use of intravenous drugs. The authors concluded that the findings were not unequivocally due to marihuana.

Hochman and Brill (1971) noted abnormal liver function tests in 10 of 50 frequent marihuana users. However, all admitted to long-term, regular and heavy use of alcohol. When these subjects abstained from alcohol for one month but continued their usual marihuana usage, evidence of disturbed liver function cleared in nine out of 10 subjects.

Recently, Liskow et al. (1971) reported the appearance of an anaphylactoid reaction in a 29year-old woman after smoking marihuana for the first time. Skin tests were positive for an allergy to marihuana, constituents. Allergy to marihuana, especially in areas of the country where it grows wild, may be more common than generally believed.

Campbell et al. (1971) presented evidence of ventricular dilatation consistent with cerebral atrophy by air encephalography in 10 young males (average age 22) with histories of consistent marihuana use for three to 11 years as well as less frequent use of LSD and amphetamines. The first four of the patients had been referred originally for neurological investigation of behavioral change, memory loss or headache. The remaining six subjects were selected from patients tinder treatment for drug abuse because of their long history of marihuana use and concomitant neurological and behavioral symptoms.

However, the patients showed personality behavioral and mental disorders, as well as histories of head trauma and psychomotor or grand mal epilepsy that are commonly associated with ventriculographic changes. Also alcoholism can be associated with these findings. Additionally, the authors compared their subjects ventriculograms with those of normal young adults originally referred for loss of consciousness, syncope and headache without subsequent development of neurological illness.

Thus, the authors demonstrated dilation of the third ventricle, of the frontal or temporal horn, or of the trigone of the lateral ventricle. All of these are commonly associated with personality and mental disorders such as these patients shelved. However, whether these changes are caused by marihuana is not proven because no specific neuropathological cause for the cerebral atrophy was identified. Further carefully designed studies are required to clarify this finding.

The LaGuardia Report (Mayor's Committee, 1944) indicated no damage to the cardiovascular, digestive, respiratory and central nervous system, nor the liver, kidney or blood in individuals who had used from two to 18 cigarettes of unknown potency (average seven) for a period of two-and a-half to 10 years (average eight). However, this study was not up to modern standards as it lacked double-blind precautions and placebo controls and adequate statistical analysis of the data. Bias was present in reporting. Small numbers of prisoners were used as subjects.

Another less comprehensive American study of 310 individuals who used marihuana on the average of seven years was performed on soldiers (Freedman & Rockmore, 1946). It did not demonstrate any evidence of physical or mental deterioration.

Another team of investigators (Meyer et al., 1971; Mirin et al., 1970) examined a group of 10 male marihuana users (average age 25) who had consumed the drug about 20 to 30 times a month for all average of 4.4 years (one-half to five year range) and had smoked daily for three of the 4.4 years. Heavy use was correlated with psychological dependence, search for insight or meaningful experience, multi-drug use, poor work adjustment, diminished goal directed activity, decreased ability to master new problems, poor social adjustment and poorly established heterosexual relationship. No physical or neurological or psychiatric abnormalities were noted in their work-up.

Indeed, numerous American investigators have not reported abnormalities in baseline, examinations of their experimental subjects who have various patterns of marihuana use from very infrequent to many times a day.

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