The importance of weeds in ethnopharmacology.

Tropical primary forest is often considered to be the most important habitat for traditional peoples to gather medicinal plants. However, the role of weeds, commonly found in disturbed areas, in traditional medicinal floras has been overlooked. Data are presented showing the significant representation of weeds in the medicinal floras of the Highland Maya in Chiapas, Mexico and in the medicinal flora of Native North Americans as a whole. The frequency with which weeds appear in these pharmacopoeias is significantly larger (P<0.0001) than what would be predicted by the frequency of weed species in general. Explanations based on human ecology and biochemical ecology are presented.

Reviewing the reviews. How strong is the evidence? How clear are the conclusions?

OBJECTIVES: The objectives of this paper were: a) to determine what can be learned from conclusions of systematic reviews about the evidence base of medicine; and b) to determine whether two readers draw similar conclusions from the same review, and whether these match the authors' conclusions. METHODS: Three methodologists (two per review) rated 160 Cochrane systematic reviews (issue 1, 1998) using pre-established conclusion categories. Disagreements were resolved by discussion to arrive at a consensual score for each review. Reviews' authors were asked to use the same categories to designate the intended conclusion. Interrater agreements were calculated. RESULTS: Interrater agreement between two readers was 0.68 and 0.72, and between readers and authors, 0.32. The largest categories assigned by methodologists were "positive effect" (22.5%), "insufficient evidence" (21.3%), and "evidence of no effect" (20.0%). The largest categories assigned by authors were "insufficient evidence" (32.4%), "possibly positive" (28.6%), and "positive effect" (26.7%). CONCLUSIONS: The number of reviews indicating that the modern biomedical interventions show either no effect or insufficient evidence is surprisingly high. Interrater disagreements suggest a surprising degree of subjective interpretation involved in systematic reviews. Where patterns of disagreement emerged between authors and readers, authors tended to be more optimistic in their conclusions than the readers. Policy implications are discussed.

Cultural variations in the placebo effect: ulcers, anxiety, and blood pressure.

An analysis of the control groups in double-blind trials of medicines demonstrates broad variation--from 0 to 100 percent--in placebo effectiveness rates for the same treatment for the same condition. In two cases considered here, drug healing rates covary with placebo healing rates; placebo healing is the ultimate and inescapable "complementary medicine." Several factors can account for the dramatic variation in placebo healing rates, including cultural ones. But because variation differs by illness, large placebo effects for one condition do not necessarily anticipate large placebo effects for other conditions as well. Deeper understanding of the intimate relationship between cultural and biological processes will require close ethnographic scrutiny of the meaningfulness of medical treatment in different societies.

Toward a research agenda on placebo.

The placebo effect is about healing. The human healing process can be substantially influenced in actual medical practice by appropriate kinds of caring, communication, and patient empowerment. The creation of "meaning" and of "representations" by physicians and their patients can have dramatic effects on patients for good or ill. These effects are potentially as important in procedures such as surgery or chiropractic as they are in medicine generally. Placebo processes can substantially affect the overall response to health care and its cost, yet very little research specifically explores these phenomena. An explicit research agenda should be developed to investigate the influences of belief, context, and meaning in medicine. Such a research agenda would have significant beneficial scientific and policy consequences. In addition, it would enhance our understanding of those healing processes that underlie most if not all of medicine.

Placebo effect in the treatment of duodenal ulcer.

AIMS: To assess whether frequency of placebo administration is associated with duodenal ulcer healing. METHODS: A systematic literature review of randomized clinical trials was undertaken. 79 of 80 trials that met the inclusion criteria. The pooled 4 week placebo healing rate of all duodenal ulcer trials that employed a four times a day regimen was compared with the rate obtained from trials with a twice a day regimen. RESULTS: The pooled 4 week healing rate of the 51 trials with a four times a day regimen was 44. 2% (805 of 1821 patients) compared with 36.2% (545 of 1504 patients) in the 28 trials with a twice a day regimen (difference, 8.0% [equal effects model]; 95% confidence interval, 4.6% to 11.3%). Depending on the statistical analysis, the rate difference ranged from 6.0% (multivariable random effects model) to 8.0% (equal effects model). A number of sensitivity analyses showed comparable differences between the two regimens. Most of these sensitivity analyses were not significant, probably because a number of trials were excluded resulting in a loss of power. CONCLUSIONS: We found a relation between frequency of placebo administration and healing of duodenal ulcer. We realize that the comparison was based on nonrandomized data. However, we speculate that the difference between regimens was induced by the difference in frequency of placebo administration. A better knowledge of various placebo effects is required in order to make clinically relevant assessments of treatment effects derived from placebo-controlled trials.

An analysis of the food plants and drug plants of native North America.

This paper compares the medicinal and food floras of the native peoples of North America. There is a surprising overlap of these floras by both family and taxon. Yet there are also substantial differences-food and medicine tend to involve different plant parts, plant habit, and plant character. The similarities and differences are considered in an evolutionary context and a theoretical perspective is suggested to account for these facts.

The medicinal flora of Native North America: an analysis.

This paper describes an analysis of the plants of North America which have been used medicinally by Native North Americans. A method using regression residuals is developed for analyzing large quantities of data, divided into subgroups of varying sorts and sizes. The analysis shows that the medicinal species utilized by Native North Americans are distributed in a highly non-random fashion across subclasses and families as well as across groups defined in terms of growth habit and life pattern. This distribution makes sense in terms of both the defensive chemistry and the "complexity" of plants.

"Functioning" from the perspective of production supervisors.

Ethnographic research at two work activity centers revealed the hidden connotations of "functioning" in production supervisors' discussions of high functioning and lower functioning clients. Teachers at the centers defined functioning in narrowly academic terms, whereas supervisors used the term to connote a whole set of mental, physical, and moral traits related to job performance. Implications for communication among staff members and for treatment of clients were considered.

Symbols and selectivity: a statistical analysis of native American medical ethnobotany.

Native Americans use a wide range of plants medicinally. Many of these plants have profound meaning to their users. Does this mean, as some assert, that tribal medicine is "all placebo"? Since the essential character of meaning is the arbitrariness of the sign, then insofar as this medicine is symbolic, the plants used medicinally will be a random representation of plants available in nature. Several regression analyses of plants used by native Americans on plants available to them indicate substantial selectivity in plant use. Native American medical ethnobotany is not only placebo medicine.