Abstract and Introduction
Objective—The effect of diabetes on mild cognitive impairment (MCI) and its conversion to dementia remains controversial. We sought to examine whether diabetes and pre-diabetes are associated with MCI and accelerate the progression from MCI to dementia.
Research design and methods—In the Kungsholmen Project, 963 cognitively intact participants and 302 subjects with MCI (120 with amnestic MCI [aMCI ] and 182 with other cognitive impairment no dementia [oCIND]) age ≥75 years were identified at baseline. The two cohorts were followed for 9 years to detect the incident MCI and dementia following international criteria. Diabetes was ascertained based on a medical examination, hypoglycemic medication use, and random blood glucose level ≥11.0 mmol/l. Pre-diabetes was defined as random blood glucose level of 7.8–11.0 mmol/l in diabetes-free participants. Data were analyzed using standard and time-dependent Cox proportional-hazards models.
Results—During the follow-up period, in the cognitively intact cohort, 182 people developed MCI (42 aMCI and 140 oCIND), and 212 developed dementia. In the MCI cohort, 155 subjects progressed to dementia, the multi-adjusted hazard ratio (95% CI) of dementia was 2.87 (1.30–6.34) for diabetes, and 4.96 (2.27–10.84) for pre-diabetes. In a Kaplan-Meier survival analysis, diabetes and pre-diabetes accelerated the progression from MCI to dementia by 3.18 years. Diabetes and pre-diabetes were neither cross-sectionally nor longitudinally associated with MCI.
Conclusions—Diabetes and pre-diabetes substantially accelerate the progression from MCI to dementia, and anticipate dementia occurrence by more than 3 years in people with MCI. The association of diabetes with the development of MCI is less evident in old people.
The impact of diabetes on cognitive function has been addressed in several studies showing that type 2 diabetes is associated with cognitive decline in aging. Furthermore, many large population-based longitudinal studies have demonstrated an increased risk of dementia in people with diabetes, but the association of diabetes with Alzheimer's disease is less evident in some studies.[2,3] Overall, diabetes leads to a 20–70% greater decline in cognitive performance, and a 60% higher risk of dementia. Even pre-diabetes, the condition of impaired glucose regulation, has been related to cognitive decline and an increased risk of dementia,[5,6] although a cross-sectional study found no association of impaired fasting blood glucose with cognitive function. In addition, three studies addressing the relation between diabetes and mild cognitive impairment (MCI) have also shown conflicting results.[8–10]
MCI represents the usual transitional phase from normal cognitive function to dementia, although not all people with MCI will develop dementia. Different criteria and subdivisions of MCI have been proposed and modified over time. MCI has been subdivided into two major forms—amnestic MCI (aMCI) and other domain cognitive impairment no dementia (oCIND).[13–15] Progression to clinically diagnosable dementia occurs at a higher rate from MCI than from unimpaired cognition; the estimated rate of conversion is approximately 30% over 3 years. However, the extent to which diabetes accelerates this progression is unclear. Only two population-based studies have addressed this issue and both showed nonsignificant effect of diabetes on the conversion from MCI to dementia.[10,17]
Most studies that have addressed the association of diabetes with dementia included people with MCI at baseline assessment as nondemented and people with pre-diabetes with a nondiabetic group. These studies may underestimate the risk of dementia associated with diabetes. We have demonstrated that diabetes and pre-diabetes increase the risk of dementia and its main subtypes.[5,18–20] In the present study, we sought to investigate the association of diabetes and pre-diabetes with the risk of MCI and to verify the hypothesis that diabetes and pre-diabetes may accelerate the progression from MCI to dementia.
Diabetes. 2010;59(11):2928-2935. © 2010 American Diabetes Association, Inc.
Cite this: Accelerated Progression from Mild Cognitive Impairment to Dementia in People with Diabetes - Medscape - Nov 01, 2010.