A Critique of Animal Psychology Research at the University
of California at Berkeley
Brandon P. Reines, D.V.M.
Biorhythm research: Dr. Irving Zucker and Dr. Seth Roberts
Funded by over $1 million by the National Institute of Child Health and Human Development, Zucker has experimented on small mammals such as voles, hamsters, and ground squirrels since 1971. Zucker has long studied the effects of different "day lengths" and brain lesions on sexual and other behaviors in small mammals. Zucker, who is one of the best-known biorhythm researchers (for example, see Rusak and Zucker, 1979), uses approximately 250 ground squirrels and 70 European hamsters per year for his research.
Roberts, a protege of Zucker, has received about $77,000 from the NIMH and used approximately 200-300 rats per year over the past few years. Roberts has trained rats to press a certain lever depending upon whether it "experiences" the duration of a sound as short or long. Based on his studies, Roberts claimed that rats can be trained to alter their experience of time duration or to "reset their internal clock." Roberts' (1985) research is aimed at understanding the "properties of an internal clock." The implicit aim of such animal research is to elucidate the physiological basis of human "time sense." Many psychologists, however, now consider the search for an "internal clock" to be misguided. For example, Dr. Robert Ornstein, a University of California at San Francisco psychologist, wrote:
Albert Einstein once jokingly explained, 'When you sit with a nice girl for two hours, it seems like two minutes; when you sit on a hot oven for two minutes, it seems like two hours. That's relativity.' Many psychologists, ignoring that the ordinary temporal experience is personally and relativistically constructed, have searched for an internal organ of duration rooted in one biological process or another. This postulated 'organ' has been termed a biological clock ... We cannot postulate an internal biological clock as the basis of ordinary temporal experience. A multiplicity of physiological processes, such as heart rate and basal metabolism, have been suggested as the clock, but many experiments have shown that these processes each seem to move at different rates. No single internal process that could be the biological clock has been found. There are, of course, many internal rhythmic processes that are quite important for consciousness, but these do not necessarily relate to time as it is experienced ... The idea of a 'sense' of time may be useful in ordinary discussion, when we might wish to compare experience to the clock, to discuss someone who is habitually not 'on time,' for instance, but as a scientific metaphor it has led to a search for a nonexistent organ of time experience ... (1986, pp. 134-135).
Nonetheless, Zucker justified biorhythm research on animals as follows:
I work on biological rhythms and the role of photoperiod in their manipulation. This work has inspired clinicians to treat depressives with bright lights in mid-winter to alleviate seasonal affective disorders. Also melatonin treatments, based on animal studies are being used in a related context. Treatment of jet-lag dysfunctions and sleep-disorders in humans are based on animal work ... Statements such as the one in the Wehr et al article (on treatment of depressives with bright light) ... 'On the basis of animal models we hypothesized that ...' give a fair picture of the ways animal work impacts on clinicians. I get calls from clinical workers regularly; they usually wish to discuss their human data in the context of animal work. They have repeatedly indicated that these interactions are helpful to them. This pleases me as it provides one justification of pursuing animal research. (Zucker, 1986)
Zucker's primary claim was that biorhythm research on animals has led to an effective treatment for a disorder known as Seasonal Affective Disorder (SAD) or "winter blues." In particular, Zucker cited Wehr's (1986) clinical study to support his contention. Wehr and his co-workers have recently explored the use of Vita-Lite full-spectrum fluorescent lights for treating patients with SAD. As Zucker stated, Wehr et al. apparently credit animal studies for stimulating their clinical study:
On the basis of animal models we hypothesized that seasonal changes in sunlight acting via a photoperiodic mechanism might be responsible for changes in the clinical state in patients with SAD, and that their winter depressions might be treated by extending the short winter photoperiod five hours with bright artificial light ... (p. 870.)
Analysis of the Wehr quote, however, reveals that the animal model studies were primarily used to provide insight into the mechanism by which light therapy might alleviate SAD. It is traditional among clinical investigators to utilize animal models to rationalize a specific treatment modality by explaining how the treatment might alter the pathophysiology (mechanism) of the disease. In fact, however, the incentive to utilize bright light therapy for SAD existed long before the animal studies. A great deal of clinical and epidemiologic evidence indicated that "simulating summertime" might make SAD patients feel better. For example, Beckman and Leber wrote:
The observation of physician Peter Mueller of clear seasonal variations in the affective state of one of his patients, with winter depression and hypomania setting in in spring, which was also strongly latitude related, led him to try aborting one of her depressions with early morning light therapy ... When this treatment was successful, a larger study was undertaken at NIMH (1985, p. 281).
Thus, the animal studies did not lead to the clinical trials. Furthermore, the animal models, including Zucker's, were shown to be invalid (to the extent that any conclusions can be drawn from such a small clinical study). One of the principle conclusions of the Wehr study was that light therapy does not appear to work by a "photoperiodic mechanism", as postulated on the basis of animal models. The Wehr study actually showed that the epidemiologic evidence was right and the animal models were wrong:
Our findings with SAD unexpectedly proved to be consistent with observations based on epidemiologic data that may be relevant to seasonal effects on affective illness; Aschoff found that seasonal variations in suicide rates at different latitudes were more highly correlated with seasonal variations in the amount of clear sunshine than with seasonal variations in the photoperiod (p. 874).
Even though the animal model studies merely served to rationalize undertaking the clinical trial (an extrascientific function), and were "proven" invalid, Wehr et al. criticize animal biorhythm studies gently:
Finally, it is ironic that the well-studied animal model involving photoperiodically driven seasonal rhythms has led to a new antidepressant treatment modality for which the model may no longer be valid. However, even before these experiments, other aspects of SAD were known to be incongruent with the rodent-sheep photoperiodism model ... Any future animal model of SAD may need to incorporate behavioral and physiologic changes that are rapidly responsive to alternations in light and occur following exposure to light at any time of day (p. 875).
Ironically, the foregoing discussion is largely superfluous because there is really no conclusive evidence that light therapy is an effective treatment for SAD. The controlled studies undertaken to date with Vita-Lite therapy have involved too few patients to be definitive. Because light therapy was recently heralded on a well-known national television program, however, the public is now under the impression that a true cure for SAD exists. Following the television broadcast, the Duro-Test corporation itself began to claim that its full-spectrum Vita-Lite represents a proven remedy. In response to the unsubstantiated claims of the Duro-Test corporation, FDA's August 27 Enforcement Report carried a "Health Fraud Notice" listing the Vita-Lite Fluorescent Lamp sold by Duro-Test Corporation as a "gross deception of the consumer" because of its labeled claims. In its Sept. 10, 1986 "Talk Paper," FDA warns:
FDA cautions consumers that these claims are unsubstantiated and misleading because there is little or no clinical data derived from well-controlled scientific investigations to support use of such full-spectrum fluorescent lights for these therapeutic purposes (including SAD).
In addition to Zucker's primary claim that biorhythm research on animals has led to effective phototherapy for SAD, he contended that such animal studies have led to "melatonin treatments," as well as treatment of jet-lag dysfunctions and sleep disorders. Zucker's reference to melatonin treatments refers to the idea that melatonin may prove valuable in the treatment of depression. Although melatonin treatment actually worsens human depressives (Carman et at., 1976), a few researchers suggested that melatonin may actually prove effective if administered at a specific time in the human circadian cycle (Wehr and Goodwin, 1983, p. 61). It is true that melatonin treatments "are being used," as Zucker stated, but there is no real evidence of either a direct connection between the animal and human studies or of an effective melatonin-based treatment.
Zucker's further contention that treatment of jet-lag and sleep disorders is based on animal biorhythm research also constitutes a "linguistic gimmick" for justifying animal research. Zucker was undoubtedly referring to new animal biorhythm studies of sleeping pills and tranquilizers that are already in wide clinical use (see for example, Ehret et at., 1975). Researchers such as Zucker have in fact "renamed" these old standbys. By calling such drugs "chronobiotics," biorhythm researchers lend undeserved credibility to the entire field of biorhythm research. For example, in one recent and well-publicized study (Lautman, 1986), researchers treated human jet-lag insomnia with the widely-prescribed sleeping pill, triazolam (Halcion). While the drug was really chosen because patients report so few aftereffects, animal researchers maintained that it was chosen on the basis of animal studies. In particular, researchers found that triazolam, affects the circadian rhythm of hamsters. When and if triazolam proves effective against jet-lag insomnia, animal researchers will undoubtedly claim that the triumph is a product of animal biorhythm research - when in fact it would be a result of simple clinical investigation. There is no evidence that animal biorhythm research in general or Zucker's studies in particular have led to treatments for affective disorders that are shown effective in well-controlled clinical trials.
1. Hormones and Behaviour Research
3. Mother-Infant Separation Research
6. Biorhythm Research