Higher BMI is associated with smaller regional brain volume in older adults with type 2 diabetes

• Published in: Diabetologia Vol. 63; no. 11; pp. 2446 - 2451
• Main Authors: West, Rebecca K., Livny, Abigail, Ravona-Springer, Ramit, Bendlin, Barbara B., Heymann, Anthony, Leroith, Derek, Liu, Xiaoyu, Lin, Hung-Mo, Hochner, Hagit, Friedlander, Yechiel, Ganmore, Ithamar, Tirosh, Amir, Schnaider Beeri, Michal
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-11-2020; Springer Nature B.V
• Subjects: Adipose tissue; Atrophy; Body mass index; Body weight; Cognitive ability; Dementia; Dementia disorders; Diabetes; Diabetes mellitus (non-insulin dependent); Frontal gyrus; Health risks; Human Physiology; Internal Medicine; Medicine; Medicine & Public Health; Metabolic Diseases; Obesity; Older people; Overweight; Short Communication; Substantia grisea; Temporal gyrus; Type 2 diabetes; Adiposity; Cognitive functioning; Brain volume; Middle temporal gyrus; Inferior frontal gyrus; BMI
• ISSN: 0012-186X; 1432-0428
• DOI: 10.1007/s00125-020-05264-8

Aims/hypothesis
There are established relationships between adiposity (obesity) and higher dementia risk, faster cognitive decline and associated neural injury. Type 2 diabetes is strongly linked to greater adiposity and has been consistently associated with neural injury and poor cognitive outcomes. However, although obesity is a major cause of type 2 diabetes, there is limited evidence on the association of adiposity with brain atrophy among individuals with type 2 diabetes.
Methods
We examined the association of BMI (a measure of adiposity), and of long-term trajectories of BMI (three empirically identified groups of trajectories—‘normal’, ‘overweight’ and ‘obese’—using SAS macro PROC TRAJ), with regional brain volume, in a sample of older individuals (aged 64–84) with type 2 diabetes participating in the Israel Diabetes and Cognitive Decline Study (
n
 = 198).
Results
Using linear regression, we found that greater BMI was associated with smaller volumes of the inferior frontal gyrus (IFG) (
r
 = −0.25,
p
 = 0.001) and the middle temporal gyrus (
r
 = −0.19;
p
 = 0.010) after adjusting for sociodemographic covariates and total intracranial volume. In addition, there were significant differences between BMI trajectory groups in IFG volume (
F
 = 4.34,
p
 = 0.014), such that a long-term trajectory of obesity was associated with a smaller volume. Additional adjustment for cardiovascular and diabetes-related potential confounders did not substantively alter the results. There were no associations of adiposity with superior frontal gyrus, middle frontal gyrus or total grey matter volumes.
Conclusions/interpretation
In older adults with type 2 diabetes, long-term adiposity may have a detrimental impact on volume of brain regions relevant to cognitive functioning. Further studies to identify the underlying mechanisms are warranted.
Graphical abstract