Lower muscle mass tied to poorer cognition in people with T2D

Having less bulk in the lower extremity skeletal muscle mass (LESM) is associated with impaired cognitive function in people with type 2 diabetes (T2D), according to the SMART2D* study.  

“LESM measurement may potentially be a useful ‘marker’ of possible co-occuring cognitive dysfunction, thereby facilitating earlier detection and management,” suggests the researchers led by Dr Lim Su Chi of Khoo Teck Puat Hospital, Singapore.

In the cross-sectional study, 1,235 participants (mean age 61.4 years, 51.9 pecent male) with T2D were assessed on LESM, upper ESM (UESM), and appendicular skeletal muscle index (SMI) using bioelectrical impedance analyses (BIA). They also underwent Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) for cognitive performance. [Sci Rep 2020;10:2956]

Compared with the reference LESM tertile, participants in the two lower tertiles of LESM (tertiles 1 and 2) had significantly lower RBANS total score (b=-2.62 and -1.73 for tertiles 1 and 2, respectively; p<0.001 for both vs reference).  

Cognitive performances in specific domains such as immediate memory (b=-3.75; p=0.001 and b=-1.98; p=0.023 for tertiles 1 and 2, respectively) and delayed memory (b=-3.05; p=0.001 and b=-1.87; p=0.008, respectively) were also significantly poorer in the two lower tertiles of LESM compared with the reference tertile.    

Similarly, participants in the lowest LESM tertile performed signicantly worse in visuospatial/constructional ability than the reference tertile (b=-2.99; p=0.011).

All the associations above persisted even after adjusting for multivariables including age, gender, blood pressure, LDL cholesterol, diabetes duration, body mass index, and body fat — indicating that the the association between muscle mass and cognition was independent of the metabolic factors.    

In addition, the two lower tertiles of SMI were also associated with poorer performance in delayed memory compared with the reference tertile (b=-1.94; p=0.041 and b=-1.75; p=0.013 for tertiles 1 and 2, respectively).

Conversely, there was no relationship between UESM and cognitive performance.

“The association between LESM and specific cognitive domains on immediate memory, delayed memory, and visuospatial/constructional ability highlights the need to focus on aspects of diabetes self-care and management which require the use of such domains,” said Lim and co-authors.

Loss of muscle mass, or sarcopenia, may share a common aetiology with cognitive impairment — age-related inflammation, according to the researchers, who noted that both conditions are common among older adults with T2D.  

“Future studies should follow up persons with diabetes to establish whether baseline muscle mass predict subsequent risk of cognitive impairment/decline or whether sarcopenia and reduced cognitive function are both outcomes of the same pathophysiological processes,” they said.

As the study population is restricted to those with T2D, the results should not be extrapolated to community-dwelling older people without T2D. The researchers also could not determine if the association between LESM and cognitive function was mediated by physical activity, due to lack of data.  

“[Our results]  highlighted the need for closer attention in specific areas of diabetes self-care or management such as medication adherence, self-monitoring of blood glucose, and appointment keeping,” said the researchers.