Blackwell Publishing AsiaMelbourne, AustraliaPSYPsychogeriatrics1346-35002006 Japanese Psychogeriatric SocietyMarch 2006611920Original ArticleOlfactory dysfunction and dementiaN. Motomura and Y. Tomota
PSYCHOGERIATRICS 2006; 6: 19–20
ORIGINAL ARTICLE
Olfactory dysfunction in dementia of Alzheimer’s type and vascular dementia Naoyasu MOTOMURA1 and Yoji TOMOTA2
1
National Mental Support Center for School Crisis, Osaka Kyoiku University, Osaka and 2Department of Neurology, Hyogo Rehabilitation Center, Kobe, Japan
Correspondence: Naoyasu Motomura MD, National Mental Support Center for School Crisis. 1-2-10 Midorigaoka, Ikeda, Osaka, Japan. Email:
[email protected] Received 27 July 2005; accepted 26 September 2005.
Key words: dementia of Alzheimer’s type, olfaction, vascular dementia.
Abstract Background: Olfactory function in vascular dementia has not been extensively investigated to date. We studied olfactory function in vascular dementia (VD) and dementia of Alzheimer’s type (DAT). Methods: We studied olfactory functioning in 12 patients suffering from dementia of Alzheimer’s type, 11 patients with vascular dementia and 30 normal subjects. For these subjects we examined a 12-item version of the Pennsylvania smell identification test and mini-mental state examinations. These three groups were matched for age, sex and educational level. Results: Although the dementia scores were comparable in the DAT and VD groups, the smell identifications were low in DAT patients compared with VD patients and normal control subjects. Conclusions: These results suggest that the smell identification test may be useful in differential diagnosis between DAT and VD patients
INTRODUCTION People with dementia manifest many neurobehavioral problems.1–3 In recent years olfactory disturbances have been reported in patients with Alzheimer’s diseases.4–7 However, to our knowledge, disturbances of the olfactory function are very rare in vascular dementia.8 In this study we conducted olfactory identification tests on patients with dementia of Alzheimer’s type (DAT), vascular dementia (VD) and control subjects, and detected the olfactory dysfunction in cases with DAT and VD.
SUBJECTS AND METHODS Subjects of the study consisted of 30 normal controls, 12 patients with DAT and 11 VD patients. The diagnosis of dementia was performed according to DSM-IV’s diagnostic criteria, NINCDS-ADRDA or NINCDS-AIREN. We obtained informed consent from subjects and their families. Subjects had no history of rhinitis or pararhinitis in the present study. We conducted a 12-item version of the Pennsylvania University smell identification test and minimental state examination (MMSE) for the patients and
control subjects. The smell identification test was developed by Doty and has been used world-wide to test smell identification. Each item consists of a card with a scent-impregnated area that is activated by scratching. Above these areas are four potential responses for identifying the odor. Each subject was asked to sniff the scratched impregnated area and then tell the examiner the correct response from the four alternatives on the card. The MMSE comprises items regarding orientation, digit span, memory, naming repetition, reading, writing and drawing and provides measures of the basic neuropsychological functioning of the patient.8 One-way analysis of variance by Bonferroni test was employed for detecting statistical differences.
RESULTS Table 1 shows the means and standard deviations for age, MMSE scores, education and smell identification scores of the three groups. There were no statistically significant differences among the three groups in age or education. Differences were found among the three groups on the MMSE score (F2,52 = 8.0, P < 0.01) and 19
N. Motomura and Y. Tomota Table 1 Olfactory disturbances in dementia of Alzheimer’s type (DAT) and vascular dementia (VD)
Number of subjects Age Education Mini-mental state examination Olfaction
Control
DAT
VD
30 70 ± 4.5 8 ± 1.0 25.8 ± 2.7
12 69 ± 3.8 9.2 ± 2.3 12.5 ± 2.8*
11 71 ± 6.5 8.5 ± 1.5 11.7 ± 2.9*
9.4 ± 3.0
3.5 ± 2.8*
6.8 ± 2.3
*P < 0.01 The values for the last four items are means ± standard deviations.
smell identification score (F2,52 = 8.5, P < 0.01) by analysis of variance. Subordinate analysis using the Bonferroni adjustment for P = 0.01 indicated that the scores on MMSE were low in the DAT (t = 3.1, P < 0.01) and VD groups (t = 2.8, P < 0.01) compared with the control subjects. There were no differences in MMSE scores between the DAT and VD groups. The scores for the smell identification test were significantly low in the DAT group compared with the VD (t = 3.3, P < 0.01) and control groups (t = 2.9, P < 0.01). There were no significant differences between the scores of the control and VD groups.
DISCUSSION We assessed olfactory identification in patients with DAT and VD. Our results indicated that a lower score was found in DAT patients. These results are consistent with past reports.5,6,9,10 In contrast with this finding, we did not find a low score in VD patients. Gray et al. reported that both DAT and VD patients demonstrated comparable disturbances in smell identification tests.7 The reason for the inconsistency of past reports relate to the lesion sites in the VD patients in the present cases. The olfactory pathway includes the olfactory bulb, the entorhinal cortex, the hippocampus, the amygdale, the thalamus and the hypothala-
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mus etc. The patients with VD studied may not include any with vascular damage in the olfactory systems, which is important for olfactory dysfunction. Therefore, we think that our patients with VD did not show smell identification disturbances. These results imply that the smell identification task may be an indicator for the differential diagnosis for DAT and VD. As we could study only a small number of patients with dementia, this pilot study demonstrates the need for further research on olfactory identification in people with dementia.
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