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Caroline Tanner Background: Parkinson's disease (PD) is a neurodegenerative disease characterized by the loss of dopamine producing neurons in the substantia nigra region of the brain. PD usually strikes in the fifth decade of life. Tremors and loss of motor control are the primary symptoms but cognitive function and sensory impairments have also been reported. One of the most common sensory problems is the ability to detect and discriminate odors. The impairment of the sense of smell is so common in Parkinson's patients it is has been suggested as a possible diagnostic tool. The cause currently unknown; however, the impairment has been attributed to an inability to process sensory signals and inputs. Advance: These investigators report that problems in sniffing contribute to the olfactory impairment. Experiments confirmed that PD patients were less able to detect and identify controlled odors; however, PD patients had impaired abilities to sniff as measured by air flow and volume. When instructed to sniff more vigorously, some patients were able to score better on the smell identification tests. However, increasing sniff volume only helped the worst performers and did not improve their performance to the level of the control group. Implication: These findings do not suggest that a decreased ability to sniff is the only cause of olfactory impairment in people with PD. The authors speculate that it works in combination with damage to the neural pathways of the olfaction system. However, by simply providing a verbal cue to sniff more vigorously, PD patients were able to detect smells better suggesting quality of life implications such as the ability to detect hazards or enjoy pleasant odors. Publication: Sobel N, Thomason ME, Stappen I, Tanner CM, Tetrud JW, Bower JM, Sullivan EV, Gabrieli JD. An impairment in sniffing contributes to the olfactory impairment in Parkinson's disease. Proc Natl Acad Sci U S A. 2001 Mar 27;98(7):4154-4159. |
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