| Abstract [eng] |
Dementia is a leading cause of disability and dependency globally. The prevalence of dementia is continuously increasing. Consequently, the social and economic impacts of the disease are becoming major issues, making it a global healthcare priority. Therefore, identifying affordable and widely accessible measures to achieve accurate diagnosis is increasingly important. Alzheimer’s disease (AD) is the most common cause of dementia and is estimated to cause 60–70% of all cases. Olfactory dysfunction is not only a common symptom, but also a very early sign of AD. Therefore, olfactory testing could be useful as a simple, non-invasive and affordable marker for diagnosing early-stage AD. This doctoral dissertation is based on four published research articles. We analysed odour identification and odour discrimination in patients with early-stage AD, as well as diagnostic properties of odour identification and odour discrimination testing for diagnosing early-stage AD. In order to improve applicability of olfactory testing in everyday practice, the performance of patients with early-stage AD in identifying and discriminating specific odorants and diagnostic properties of shortened versions of odour identification and odour discrimination tests for diagnosing early-stage AD were tested. We have also analysed olfactory memory in patients with early-stage Alzheimer’s disease and explored the differences between olfactory and verbal memory deficits. We determined that odour identification and odour discrimination are impaired in early-stage AD. We found odour identification and odour discrimination testing to have good diagnostic properties for differentiating patients with early-stage AD from healthy subjects. Shortened versions of odour identification and odour discrimination tests that were created based on performance of patients with early-stage AD also have good diagnostic properties for differentiating patients with early-stage AD from healthy subjects. Finally, our data shows that olfactory memory is impaired in patients with early-stage AD but demonstrates a different pattern of impairment than verbal memory. |
