Review: Assessment of Cognitive Status in Patients with Type 2 Diabetes With the MMSE

The paper reviewed here is ‘Assessment of Cognitive Status in Patients with Type 2 Diabetes Through the Mini-Mental Status Examination: A Cross-Sectional Study’ by Alencar and colleagues and freely available here. There is a large research base on cognition in Type II Diabetes and at the time of writing a search of medline using the keywords ‘Diabetes’ and ‘MMSE’ returned 152 results of varying degrees of relevance. The study reviewed here is by a Brazilian group who conclude that

‘We conclude that patients with type 2 diabetes should be regularly evaluated for their cognitive function, because duration of disease could be associated with decline in cognition‘

Introduction

In the introduction, the researchers write that

‘Cognitive impairment might be another factor associated with poor diabetes control and also with bad adherence of patients to educational approaches, such as diet orientations‘

and thus emphasise the importance of recognising cognitive impairment if it is present. They also outline epidemiological aspects of diabetes, contextualising the current research questions. The researchers outline the aims of the study as

‘to evaluate the cognitive status of patients with type 2 diabetes and to evaluate factors associated with impaired function detected by MMSE‘

Method

This researchers use a cross-sectional design. 346 subjects with a diagnosis of Type 2 Diabetes were selected. The criteria for diagnosis are given as are the exclusion criteria. The exclusion criteria of ‘psychiatric disorders’ is rather broad and it wasn’t clear how these were excluded. A proportion of psychiatric disorders will go undiagnosed and some studies will use scores on tools such as the BDI as proxy markers. Removing subjects with established diagnoses of stroke and ‘psychiatric disorders’ also restricts the population to which these results can be generalised but presumably the intention is to avoid confounding of the results. A number of outcome measures were used in addition to MMSE scores including blood pressure, cholesterol levels, glycoslyated haemoglobin, weight and height. The researchers stipulated the statistical methods to be used for the different data types and use SPSS 13.0.

Results

62% of subjects were female with a mean age of 58.6 and mean duration of diabetes of 12.3 years. 77% of the sample were diagnosed with hypertension and 76.9% with dyslipidaemia. The mean MMSE score was 26 with a range of 16 to 30. However there is no comparator group to contextualise this score. There was an interesting finding in that subjects that needed help taking their medication had a clinically and statistically significant difference from those that did not need this help. The association of MMSE scores with hypertension was consistent with other research findings but was was interesting was that this relationship lost significance after controlling for duration of diabetes and the same also held for dyslipidaemia and diabetes. The relationship between MMSE scores and duration of diabetes was statistically significant and in the expected direction even after controlling for age.

Discussion

The researchers discuss a number of points. Among the most interesting points for me were the additive effects of diabets and hypertension on MMSE scores which has been reported elsewhere. Intriguingly there was no significant correlation between glycosylated haemoglobin scores and MMSE. The researchers also acknowledge some limitations in their study design such as the absence of additional psychometric instruments as well as the absence of MRI scans. However for the purposes of this study, I would argue that the researchers have shown that the MMSE can be a useful test as it has picked up some expected findings.

Conclusions

I think the researchers have provided evidence of a useful role for the MMSE in assessing cognition in diabetes II. A prospective design would be helpful in confirming the relationship between diabetes, hypertension, dyslipidaemia and MMSE scores and in such a design a control group would offer a useful comparison for interpreting the results.

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