Table 2 Studies identified with brain structure (+/− brain function) and muscle structure
Authors | Year | Country and dataset | n | Study design | Mean age (sd) | Male (%) | Brain structure/Function | Muscle structure | Associations* |
|---|---|---|---|---|---|---|---|---|---|
1. Heymsfield et al. [26] | 2012 | Germany | 260 | Cross-sectional study | M 45.1 (14.9), F 38.6 (13.7) | 43.1 | Structure: Brain volume transformed into mass using 1.036 g/cm3 | DEXA for FFM | Study: Linear regression models found that after adjusting for age and fat mass, FFM predicted brain mass in men (beta 0.023, R2 5%, p = 0.01) and women (beta 0.003, R2 6%, p = <0.0001). |
Function: not measured | |||||||||
2. Kilgour et al. [27] | 2013 | UK, MacLullich Healthy Elderly Men Study | 51 | Longitudinal ageing study | 73.8 (1.5) | 100 | Structure: Whole brain, hippocampal, ventricular, cerebellar volumes and ICV | Neck muscle CSA on MR head scan | Study: Total neck muscle CSA was found to predict 17% of the variance in whole brain volume (t = 2.86, p = 0.01). However, total neck muscle CSA did not significantly predict the variance in ventricular, hippocampal or cerebellar volumes (p > 0.05). Total neck muscle CSA did not significantly predict variance in either the memory factor or the cognitive processing factor (p > 0.05), however, it did predict 10% of the variance in the NART score (t = −2.12, p < 0.05). Adjusting for age, sex, ICV and NART where appropriate. |
Function: 9 tests of cognitive function reduced to 2 factors (cognitive processing factor and memory factor) | |||||||||
3. Wetmore et al. [28] | 2011 | USA, Kansas, Brain Aging Project | 60 | 2 year observational case–control study (Alzheimer’s dementia vs. non-dementia) | 73.0 (7.2) | 43.4 | Structure: MRI for WM, GM, CSF, WBV and ICV | DEXA for lean mass and ASM (just arms and legs) | Study: none |
Function: Logical Memory I & II, Free & Cued Selective Reminding Task, Boston naming test, Verbal fluency, Digit span forward and backward, Letter-number sequencing, Trail making A & B, Stroop color-word test and Block design, MMSE | Calculated: Non-demented group only. WBV, GM volume and hippocampal volume not predicted by TLM adjusting for age, sex and ICV +/− education. WM volume was predicted by TLM (t 3.12, p = 0.003, partial eta squared 14%) adjusting for age, sex and ICV. TLM did not significantly predict global cognitive score or MMSE, adjusting for age and sex. Adjusting for height and education did not affect this. | ||||||||
4. Burns et al. [29] | 2010 | USA, Kansas, Brain Aging Project | 70 | Cross-sectional case–control study (Alzheimer’s dementia (AD) vs. non-dementia) | 73.3 (7.3) | 42.9 | Structure: MRI for WM, GM, CSF, WBV and ICV | DEXA for total lean mass | Study: Positive relationship between WBV and TLM when control and AD subjects grouped together (beta = 0.20, p < 0.001), adjusting for ICV, age and sex. This appears to be driven by WM (beta 0.19, p < 0.001) rather than GM (beta 0.06, p = 0.27) States this persists in just the control group but doesn’t give any statistics for this. Positive relationship between MMSE and global cognitive score (composite of the cognitive tests) and lean mass when grouping AD and control subjects together. States that controlling for dementia status attenuates these results, but no specific statistics given. Calculated: See Wetmore et al. (2011) for Kansas Brain Aging Project data analysis. |
Function: Logical Memory I & II, Free & Cued Selective Reminding Task, Boston naming test, Verbal fluency, Digit span forward and backward, Letter-number sequencing, Trail making A & B, Stroop color-word test and Block design, MMSE | |||||||||
5. Honea et al. [30] | 2009 | USA, Kansas, Brain Aging Project | 56 healthy controls | Cross-sectional case–control study (Alzheimer’s dementia vs. non-dementia) | 73.3 (6.2) | 41.1 | Structure: MRI for GM, WM, CSF, WBV, hippocampal and parahippocampal volumes | DEXA for total lean mass | Study: none |
Function: MMSE | Â | Calculated: See Wetmore et al. (2011) for Kansas Brain Aging Project data analysis. | |||||||
6. Weise et al. [31] | 2013 | USA, Phoenix | 76 | Cross-sectional study | 32.1 (8.8) | 31.6 | Structure: MRI brain volumes (GM, WM, CSF, regional GMV) | DEXA, FFMI (FFM/height2) | Study: Fat-free mass index (FFMI) was negatively associated with GMV of the bilateral temporal lobes, ventromedial prefrontal cortex (vmPFC) (mainly subgenual portion of the ACC) and caudolateral orbitofrontal cortex and unilaterally with the left insular cortex (all p < 0.01). After adjusting for percentage body fat and fat mass, negative associations of FFM with GMV of the right temporal pole and bilateral vmPFC remained. All models adjusted for age, sex and handedness. |
Function: not measured |