Dementia and its associations in type 2 diabetes mellitus: the Fremantle Diabetes Study

BACKGROUND: recent studies indicate that diabetes is an important risk factor for dementia in older patients, but the cause remains unknown. OBJECTIVES: to determine whether vascular or diabetes-related risk factors predict the development of dementia in older subjects with diabetes. PATIENTS: 63 patients with type 2 diabetes of mean age 75.3 years. METHODS: Subjects were screened for cognitive impairment using the Mini-Mental State Examination (MMSE) and informants who knew the subjects answered the Informant Questionnaire for Cognitive Decline in the Elderly (IQCODE). Probable dementia was diagnosed using highly specific criteria based on the combination of both tests. Potential risk factors for dementia obtained at the time of the cognitive test and annually from a median of 3.2 years previously were examined using univariate methods and simple general linear modelling. RESULTS: since there was a significant association between MMSE and English speaking ability, ten non-Anglo-Celt patients were excluded from the analysis. Probable dementia was diagnosed in six of the remaining 53 subjects (11%). Dementia was significantly and independently associated with higher diastolic and mean arterial blood pressure measurements over the 3 years before assessment. Blood pressure declined over this time in the patients with probable dementia and was similar to that in non-demented subjects at the time of cognitive assessment. CONCLUSIONS: these preliminary data suggest that the high rate of dementia found in older people with diabetes may be explained by the high rate of hypertension in this population.