Sensory stimulation via the visual, auditory, olfactory and gustatory systems can modulate mood and depression

Depression is one of the most common mental disorders, predicted to be the leading cause of disease burden by the next decade. There is great deal of emphasis on the central origin and potential therapeutics of depression whereby the symptomatology of depression has been interpreted and treated as brain generated dysfunctions filtering down to the periphery. This top-down approach has found strong support from clinical work and basic neuroscientific research. Nevertheless, despite great advances in our knowledge of the aetiology and therapeutics of depression, success in treatment is still by no means assured. As a consequence, a wide net has been cast by both clinicians and researchers in search of more efficient therapies for mood disorders. As a complementary view, the present integrative review advocates approaching mood and depression from the opposite perspective: a bottom-up view that starts from the periphery. Specifically, evidence is provided to show that sensory stimulation via the visual, auditory, olfactory, and gustatory systems can modulate depression. The review shows how-depending on several parameters-unisensory stimulation via these modalities can ameliorate or aggravate depressive symptoms. Moreover, the review emphasises the bidirectional relationship between sensory stimulation and depression. Just as peripheral stimulation can modulate depression, depression in turn affects-and in most cases impairs-sensory reception. Furthermore, the review suggests that combined use of multisensory stimulation may have synergistic ameliorative effects on depressive symptoms over and above what has so far been documented for unisensory stimulation.