Fitness Linked to Brain White Matter Integrity in Aging

Cardiovascular fitness has been correlated with a variety of beneficial effects on brain structure and cognition.

These correlations have not proven causality but they do support continued imaging and brain function studies.

Scott Hayes from the VA Boston Healthcare System and Boston School of Medicine recently published an information study on this topic.

Brain white matter integrity is now open for study using diffusion tensor imaging, available from high-resolution magnetic resonance imaging (MRI).

In the current study, the research team used the following key elements in their study design:

• Subjects: 34 younger adults between 18-31 years of age and 33 older adults between 55-82 years of age free of significant medical, neurological illness without a history of traumatic brain injury.
• Fitness Testing Protocol: All subjects completed cardiopulmonary exercise testing via treadmill testing to determine fitness levels via an estimation of peak oxygen consumption.
• Imaging Protocol: Brain MRI using 3 Tesla Siemens scanner
• Statistical Analysis: Measures of white matter integrity were compared between younger and older age groups. Additionally, peak VO2 was used as a covariate interaction term.

The research team found some interesting results including the following: 

1. Older age contributed significantly to measures of impairment in white matter microstructure across a wide anatomical distribution of the white matter tracts

2. Older adults with higher level fitness estimates had higher measures of white matter integrity approaching that seen in younger adults in the following brain regions:

• splenium
• sagittal stratum
• posterior corona radiata
• superior parietal lobe

3. Fitness levels in young adults were not correlated to measures of white matter

The positive association of better white matter integrity with higher levels of cardiovasular fitness seemed to occur at about the 75th percentile performance for VO2 by age. The older age high fitness group in this study had a mean estimated peak VO2 of 37.0 ml/kg per min compared to 23.7 in the low fitness older group.

The authors note that fitness in older men has significant brain benefits but cannot completely eliminate the effects of brain aging on white matter integrity. Some regions appear more benefited by higher fitness levels than others.

A key limitation of the current study is the cross-sectional design. The cross-sectional design limits causality interpretation between fitness and brain aging. It is possible a genetic or other factor contributes to both fitness and brain aging.

This study does not inform on the potential benefits of an exercise intervention to increase VO2 on white matter integrity.

Additionally, it does not inform on the potential of using fitness exercise to prevent or reduce the cognitive impairment linked to degenerative diseases such as Alzheimer's disease. 

Nevertheless, this study does add to the growing evidence of a link between exercise and brain health. A positive effect on the brain white matter integrity may be a key component of this association.

Readers with more interest in this study can access the free full-text manuscript by clicking on the citation link below.

Image of corona radiata (posterior region area linked to improved integrity with higher fitness levels in current study) is a screen shot from the iPad app Brain Tutor.

Follow the author on Twitter at WRY999

Hayes SM, Salat DH, Forman DE, Sperling RA, & Verfaellie M (2015). Cardiorespiratory fitness is associated with white matter integrity in aging. Annals of clinical and translational neurology, 2 (6), 688-98 PMID: 26125043

Adult ADHD and Brain White Matter Deficits

In my last post I reviewed a recent diffusion tensor imaging study of ADHD in children. This study found evidence for brain white matter deficits in several ciruitry regions including frontal, temporal and occipital areas.

To follow up on this post, I want to highlight a recent study of DTI in adults with ADHD.

This study from Brazil recruited 22 drug treatment-naive subjects between the ages of 18 and 50 years of age.

This study excluded subjects with a history of substance dependence or other medical or neurological conditions that could confound the findings. However, 7 of the 22 did endorse other axis I mental disorders including 4 with bipolar disorder, 2 with major depression and 1 with anxiety disorder.

These adults subjects reported early onset of ADHD symptoms (before age 7) that persisted into adulthood.

Using all 22 with ADHD the research team reported multiple areas of differences compared to the healthy control group:

• Higher fractional anisotropy in ADHD: bilateral frontal gyrus, right middle frontal gyrus, left postcentral gyrus, bilateral cingulate gyrus, bilateral temporal gyrus and right superior temporal gyrus
• Reduced diffusivity measures in ADHD: fronto-striatal-parieto-occipital circuits, corpus callosum circuits, right superior corona radiata and fronto-occipital circuits

A significant finding in this study was the limited findings for ADHD subjects without an axis I comorbidity.

Using only these relatively "pure" ADHD subjects most of the findings lost statistical significance although a trend remained for several regions and circuits including:

• Reduced gray matter volumes in right superior frontal gyrus, right cingulate gyrus and left postcentral gyrus
• Higher fractional anisotropy in right superior frontal gyrus, right cingulate gyrus and left postcentral gyrus
• Reduced diffusivity in right splenium of the corpus callosum and white matter underlying the right cingulate gyrus

This study highlights some of the research study design problems in adult ADHD. First, many adults with ADHD will have received drug treatment and the effects of drug treatment must be controlled in the analysis. Second, many adults with ADHD will have other significant axis I disorders. These disorders may contribute to white matter deficits found with imaging. It is important to assess for these effects in reporting findings that are felt to be specific to an ADHD diagnosis.

One common comorbidity in childhood ADHD is conduct disorder and this disorder needs to be assessed in both children and adults with ADHD.

It is challenging to find subjects with only an axis I ADHD diagnosis for imaging and other types of research.

The present study supports diffuse white matter deficits in adults with ADHD although the link specifically to an ADHD diagnosis remains unclear.

Readers with more interest in this study can access the free full-text manuscript by clicking on the PMID link below.

Figure demonstrates the anatomy of the corona radiata white matter tracts in the brain and is a screen shot from the iPad app Brain Tutor. The authors found abnormalities in those with ADHD in the right corona radiata although this finding was not found in the "pure" ADHD group.

Follow the author on Twitter @WRY999

Chaim TM, Zhang T, Zanetti MV, da Silva MA, Louzã MR, Doshi J, Serpa MH, Duran FL, Caetano SC, Davatzikos C, & Busatto GF (2014). Multimodal magnetic resonance imaging study of treatment-naïve adults with attention-deficit/hyperactivity disorder. PloS one, 9 (10) PMID: 25310815

How Golf Practice Changes the Brain

Neuroscience research provides increased understanding of how behavior and specific activities change the brain.  This type of research underscores the concept of neuroplasticity--that our brains change in response to how it is used on a daily basis.

One area of research in neuroplasticity is the effect of specific cognitive and motor behavior on brain structure.  A novel study published in The Journal of Neuroscience examined the effect of golf practice on brain structure.  Bezzola and colleagues from Switzerland and Germany in this study proposed that golf practice is likely to effect the following brain regions based on their known functions:

• Dorsal stream--development of visuomotor skills
• Subcortical and cerebellar regions--motor learning
• Frontal association areas--cognitive aspects of skill development

A group of relatively novice golfers had brain scan before and after a period of 40 hours of golf practice.  This study used a real world type of design.  The golfer intervention group were directed to complete their practice under a golf instructor at their own course at their own pace.  The experimental group and control groups in this study were between the ages of 40 and 60 years of age as the goal was to examine the effect in those who were likely to begin experiencing some decline in brain cognitive function.

The brain imaging in this study was completed using magnetic resonance imaging or MRI.  This technique allows for examination of small changes in brain gray and white matter volumes.

The golf practice intervention group demonstrated significant brain volume increases in a variety of brain regions including the:

• ventral premotor cortex
• several regions in the parietal cortex including the inferior parietal cortex (area demonstrated in the attached Brain Tutor HD screen shot)
• parietal-occipital junction

The golfers in the study took up to five months to complete the 40 hours of practice.  Interestingly, those who completed their practice in the least number of days showed the greatest increase in brain volumes in at the parietal occipital junction.

The authors note their study is important because it shows brain neuroplasticity occurs not just in strictly controlled motor exercise protocols but in the real world of structured leisure activity like golf.  The note structured leisure exercise activities "may be considered an additional therapeutic setting in the process of neuro-rehabilitation.

This study also suggests middle-aged individuals have a new excuse for taking up a new physical activity like golf.  If their spouse objects to heading out to the golf course to practice, a scientific response might be: "Honey, I'm just going out to work out my brain parietal-occipital junction".

Photo of Steve Williams assisting Tiger Woods practice golf at the 2010 PGA Championship from the author's private collection.

Screen shot of the inferior parietal lobe from Brain Tutor HD iPad app.

Bezzola L, Mérillat S, Gaser C, & Jäncke L (2011). Training-induced neural plasticity in golf novices. The Journal of neuroscience : the official journal of the Society for Neuroscience, 31 (35), 12444-8 PMID: 21880905