Research reportMonorhinal odor identification and depression scores in patients with seasonal affective disorder
Introduction
It is often assumed that the human sense of smell is incapable of mediating numerous communicative functions subserved by olfaction in many other animals. Recently, however, it has been suggested that humans may influence each other’s biological rhythms via body odors (Stern and McClintock 1998).
Since neuronal connections between main olfactory pathways and limbic structures persist in humans, olfactory functioning has been a logical focus of investigation in neuropsychiatric disorders, with consistent abnormal findings in schizophrenia, Alzheimer disease and Parkinson disease Doty, 1991, Martzke et al., 1997. In depression, however, the results of olfactory testing have been mixed. No olfactory deficits were reported in some studies of non-seasonal depression Warner et al., 1990, Amsterdam et al., 1987 and seasonal depression (Oren et al., 1995), while other studies found an abnormal olfactory identification ability in nonseasonally depressed patients Serby et al., 1990, Rupp et al., 1997.
Right-posterior hemispheric abnormalities have been suggested by neuropsychological testing in patients with seasonal affective disorder (SAD) O’Brien et al., 1993, Michalon et al., 1997 and evidence of decreased left prefrontal and right-posterior activation has been found in an electrophysiological study on SAD (Allen et al., 1993). Anatomically, the olfactory system is unique among other sensory systems because of predominantly ipsilateral projections (Furukawa et al., 1988). In this study we therefore employ, for the first time in mood disorders, monorhinal odor identification testing Doty et al., 1989, Doty et al., 1992.
Olfactory circuitry has been associated with both depression and photoperiodic responses in animal studies. Indeed, the olfactory bulbectomized rat has been used as an animal model for depression (Brunjes 1992). In nonphotoperiodic animals such as rats, olfactory deafferentation unmasks photoperiodic responsiveness Nelson and Zucker, 1981, Nelson et al., 1985. In contrast, in photoperiodic animals, such as hamsters, golden-mantled ground squirrels, and the lesser mouth lemur (a photoperiodic primate), olfactory bulbectomy interferes with some of the effects of photoperiodic changes Miro et al., 1980, Ruby et al., 1993, Schilling and Perret, 1993.
Although light treatment is an effective antidepressant for patients with SAD Terman et al., 1998, Eastman et al., 1998, mood improvement after light treatment is smaller than the spontaneous improvement during summer (Postolache et al., 1998). A number of physical, chemical, biological, and socio-economic variables may account for this difference, among them, olfactory factors, given the contribution of the sense of smell to seasonal rhythms in other mammals. As the neurocircuitry responsible for seasonal changes exists latently in nonphotoperiodic animals and can be activated by lesioning olfactory pathways Nelson and Zucker, 1981, Nelson et al., 1985, we speculated that olfactory deficits may be associated with latent seasonal rhythms becoming manifest in vulnerable human individuals, namely in patients with SAD. The modulatory effect of olfaction on seasonal rhythms could be mediated via complex connections between visual and olfactory pathways, specifically convergent retinal and olfactory projections in the cortical region of the medial amygdala and lateral hypothalamus Cooper et al., 1994, Leak and Moore, 1997.
We hypothesized that olfactory performance deficits would be found in untreated depressive SAD patients, that light treatment would improve olfactory performance in patients with SAD, that the olfactory performance would correlate with the depressive scores, and that the relationship between olfactory performance and depressive scores would be lateralized.
Section snippets
Subjects and mood ratings
We studied 24 patients and 24 matched controls (Table 1), after obtaining informed consent. The protocol was approved by the Institutional Review Board of the intramural NIMH. Patients met Rosenthal criteria for SAD (Rosenthal et al., 1984) and DSM-IV criteria for a past major depressive episode. Patients with other axis I psychiatric diagnosis, current smokers, those medically ill, or with history of allergy to cosmetics, were excluded. Controls were physically healthy and free of any history
Results
Neither the PEA threshold values, nor the UPSIT scores differed significantly between the depressed SAD patients and the control subjects, or within the patients across the light treatment conditions (Table 2). No significant difference was found between the mean R-UPSIT and L-UPSIT scores. However, in depressed patients, a negative relationship was present between R-UPSIT scores and the typical depression scores (r=−0.56, P=0.006); no correlation was present between L-UPSIT and typical
Discussion
The absence of a significant difference in olfactory performance between patients and controls is consistent with some previous studies in nonseasonal Amsterdam et al., 1987, Warner et al., 1990 and seasonal depression (Oren et al., 1995). These negative findings, however, are contradicted by other reports suggesting abnormal olfactory identification ability in patients with nonseasonal depression Serby et al., 1990, Rupp et al., 1997. Methodological differences, such as differences in
Acknowledgements
We are grateful to Dan Oren, MD for his encouragement and advise at the very beginning of the project. Ludy Yi and Mulon Luo contributed to bibliographic and data management. We thank Ronald Barnett, PhD; Frances Myers, RN, MSN, Holly Lowe, MSW, Todd Hardin, MS, Kathleen Dietrich, RN for screening and rating patients. Study supported by NIMH-intramural program and by NINCD grant PO1 00161, NIH.
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2019, Handbook of Clinical NeurologyCitation Excerpt :This questions whether antidepressants, per se, alter olfactory function. Even though Postolache et al. (1999) found no UPSIT or PEA threshold differences between 24 patients with seasonal affective disorder (SAD) and 24 controls on either side of the nose, right, but not left-side, UPSIT scores were negatively correlated with “typical,” in contrast to “atypical,” depression scores (r = − 0.56, P = 0.006). While Hardy et al. (2012) found no UPSIT or PEA detection threshold differences between 20 patients with DSM-IV bipolar disorder and 44 controls, threshold sensitivity was inversely related to clinical ratings of depression on the Positive and Negative Syndrome Scale (PANSS; Kay et al., 1987).
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2017, Behavioural Brain ResearchCitation Excerpt :In particular, a small sample study in humans has indicated that depressed subjects show both decreased olfactory bulb volume and olfactory sensitivity [14]. Moreover, numerous studies have observed that patients with depression and other mood disorders have deficiencies in their ability to identify odorants [11–13,15,16]. Given this association, the removal of olfactory bulbs (OBs) has been widely used as a model of depression-like behavior.
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2014, Neuroscience and Biobehavioral ReviewsCitation Excerpt :The methods used in different studies are not always the same, complicating comparisons. Some authors used the UPSIT test (Kopala et al., 1994; Postolache et al., 1999), others a EZUS olfactory test including 16 odors (Lombion-Pouthier et al., 2006; Pentzek et al., 2007), and Swiecicki et al. (2009) used the “Sniffin’ Sticks” test. Most of the odorants used in these tests were considered as pleasant, with three exceptions (fuel, fish and garlic).