The Japanese journal of neuropsychology

Full Text of this Article
in Japanese PDF (292K)

ArticleTitle	Age at onset, persecutory delusion and misidentification delusion in late onset patients with Alzheimer's disease
Language	J
AuthorList	Azusa Kato¹⁾³⁾, Takuya Sato²⁾, Atsushi Sato²⁾, Toru Imamura¹⁾³⁾
Affiliation	¹⁾Division of Speech, Hearing and Cognitive Sciences, Graduate School of Health and Welfare, Niigata University of Health and Welfare ²⁾Division of Speech Therapy, Department of Rehabilitation, Niigata Rehabilitation Hospital ³⁾Department of Neurology, Niigata Rehabilitation Hospital
Publication	Japanese Journal of Neuropsychology: 31 (4), 269-278, 2015
Received	Mar 31, 2014
Accepted	Apr 23, 2015
Abstract	Background: Previous studies reported that the frequency of delusion is higher in late than early age at onset of Alzheimer's disease (AD), but the following issues are uncertain: 1) whether the age at onset of AD represents a quantitative or qualitative factor, and 2) whether or not the relationship to the age at onset is different between the types of delusions. Objective: To investigate the relationships between the age at onset and the frequencies of persecutory and misidentification delusions in late-onset AD patients, using a logistic regression model (for quantitative relationship) as well as a stratification model (for qualitative relationship). Subjects: 354 AD patients with age at onset of 65 years or more. The mean (±SD) age at examination was 80.4±6.0 years. Methods: We assessed the presences or absence of persecutory delusion and misidentification delusion in each patient using the Japanese version of Neuropsychiatric Inventory (NPI). Demographic characteristics and Mini-Mental State Examination (MMSE) scores were compared between patients with and without each type of delusions. We performed multiple logistic regression analysis with the presence or absence of each type of delusion as a dependent variable, the age at onset as an independent variable, and factors with significant difference between the patients with and without each delusion as covariates. We also stratified patients according to their ages at onset: young-old onset (65 to 74 years), old-old onset (75 to 84 years), and oldest-old onset (85 years or older), and compared the frequencies of each type of delusions among the 3 patient groups. Results: Of the 354 patients, 88 had persecutory delusion and 62 had misidentification delusion. In the multiple logistic regression analyses, the age at onset had a significant odds ratio for persecutory delusion only. In the stratified analyses, the frequency of persecutory delusion significantly increased with older age at onset: 17.7% in young-old onset, 27.7% in old-old onset, and 36.6% in oldest-old onset. The frequency of misidentification delusion was significantly higher in patients with oldest-old onset: 16.2% in young-old onset, 14.7% in old-old onset, and 34.2% in oldest-old onset. Conclusion: The frequency of persecutory delusion increased with older age at onset within late-onset AD. The result suggests that the age at onset of AD quantitatively related to persecutory delusion, and is consistent with the reports that AD patients with older age at onset are more likely to show the pattern of regional cerebral glucose hypometabolism characteristic for patients with delusion. The frequency of misidentification delusion was higher only in patients with oldest-old onset. The result suggests that the age at onset of AD qualitatively related to misidentification delusion. A considerable number of patients with oldest-old onset may actually be those with the earliest stage of dementia with Lewy bodies or those with limbic neurofibrillary tangle dementia, and they may tend to have misidentification delusion.
Keywords	Alzheimer's disease, age at onset, persecutory delusion, misidentification delusion, old age onset