Browsing by Subject "ideatiheys"

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  • Hyytiä, Tuuli (Helsingin yliopisto, 2019)
    Aims. The number of persons suffering from Alzheimer’s disease is increasing significantly during the decades to come. Finding means to identify the disease as early as possible is very important. Research concerning changes in written language may produce relevant information since Alzheimer’s disease weakens the ability to write already in the early stage of the disease. Changes in the amount of information conveyed have been researched internationally by measuring idea density rates. It has been found that the idea density of the persons suffering from Alzheimer’s disease is lower than that of healthy adults and that the disease accelerates the decline of idea density. Low idea density in early life is a strong predictor of Alzheimer’s disease. This study aims to determine the possible changes in the idea density of diary entries written by a person suffering from Alzheimer’s disease. Methods. The data of this study consist of diary entries written by a person who developed Alzheimer’s disease later in her life. The entries were written between 1967–2012. This study considers entries written in June of 1986, 1991, 1996, 2001, 2006, 2008, 2010, and 2012. A method for measuring idea density of Finnish written language was developed on the basis of the methods used for English and Czech. The method is manual, and it is described in detail. Idea density for each year was measured using the method. Idea density is the number of expressed propositions divided by the number of the words. Correlation between idea density and years was measured with Spearman’s rank correlation coefficient. Results and conclusions. Idea density was nearly stable until the year 2010. In 2012, idea density was lower than in other years but the change was not statistically significant. If data would have been available after the year 2012, when Alzheimer’s disease had advanced to its moderate stage, a greater change in the idea density of the diary entries might have emerged. The method developed for the study can be tested, re-developed and used in other studies regarding idea density of any text written in Finnish.