Type 2 diabetes is known to increase the risk of cognitive impairment in old age. Now analysis of data from 41 older diabetics (aged 55-81) and 458 matched controls in the Victoria Longitudinal Study has revealed that several other factors make it more likely that an older diabetic will develop cognitive impairment. These factors are: having higher (though still normal) blood pressure, having gait and balance problems, and/or reporting yourself to be in bad health regardless of actual problems.
Diabetes and hypertension often go together, and both are separately associated with greater cognitive impairment and dementia risk, so it is not surprising that higher blood pressure is one of the significant factors that increases risk. The other factors are less expected, although gait and balance problems have been linked to cognitive impairment in a recent study, and they may be connected to diabetes through diabetes’ effect on nerves. Negativity about one’s health may reflect emotional factors such as anxiety, stress, or depression, although depression and well-being measures were not themselves found to be mediating effects for cognitive impairment in diabetics (Do note that this study is not investigating which factors, in general, are associated with age-related cognitive impairment; it is trying to establish which factors are specifically sensitive to cognitive impairment in older diabetics).
In the U.S., type 2 diabetes occurs in over 23% of those over 60; in Canada (where this study took place) the rate is 19%. It should be noted that the participants in this study are not representative of the general population, in that they were fairly well-educated older Canadians, most of whom have benefited from a national health care system. Moreover, the study did not have longitudinal data on these various factors, meaning that we don’t know the order of events (which health problems come first? How long between the development of the different problems?). Nevertheless, the findings provide useful markers to alert diabetics and health providers.
 . Testing covariates of Type 2 diabetes-cognition associations in older adults: Moderating or mediating effects?. Neuropsychology [Internet]. 2010 ;24(5):547 - 562. Available from: http://psycnet.apa.org/journals/neu/24/5/547/