Oliver Grimm

A recent case in our outpatient clinic gave me an interesting insight into the link between professional sports and adult ADHD. An US-American football player who was quite impulsive presented for a diagnostic assessment. He had a history of childhood ADHD but never received stimulant treatment because his mother felt that she was able to cope by providing a structured environment. While he was not very successful in obtaining an economy degree during college, he earns nowadays money playing in foreign American football leagues. He is now 35 years old and started to think about what to do after his career ends and how his ADHD would affect future plans. He clearly fulfilled most diagnostic criteria but was not too handicapped in everyday life. Obviously, he found the perfect niche for a hyperactive adult with a high degree of impulsivity: American football. During the diagnostic assessment, he had to do a commercial continuous performance test which tests both attention as well as hyperactivity over 20 min. While his attention was not to bad, his activity during the tests was one of the highest scores we saw so far in our outpatient clinic. When talking to him about his test results, he commented that this result is typical for his adult life: professional sports taught him how to deal with his inattention and consecutive frustration. So while his ADHD was manifesting in lots of micro movements he nevertheless was able not to loose motivation and to sustain a certain degree of attention until the end of this test. So after having seen this patient, I wondered what evidence we have so far to recommend sports training in adult ADHD. Obviously, we might think of three good reasons for sports in general and in adult ADHD patients.

First, people showing a high degree of restlessness, will just enjoy sports and fitness training because it helps them to reduce their restlessness.

Second, the neurotransmitter dopamine plays a decisive role in mediating all effects in adult ADHD. There is this elegant rat experiment (by Kim et al. 2011) about the effect of a treadmill exercise on the dopamine system. Spontaneous hypertensive rats, a special breed which shows signs of hyperactivity and is considered to be an ADHD model, were given methylphenidate or treadmill exercise. While the improvement due to MPH is not surprising, treadmill exercise impacted on expression of BDNF, a marker for neuroplasticity, in the striatum and the substantia nigra.

Apart from these direct neurochemical effects, some sports training teaches how to handle frustrating challenges and not to give up early. While this is a trivial statement for every ambitious sportsmen, there are only few scientific or clinical studies in sports psychology which assessed this statement systematically and almost none for adult ADHD (please correct me if I’m wrong).

Inspired by my patient’s story, I became curious whether frustration handling could be a way of how adult ADHD patients might learn to cope with their disease. Maybe some readers have own thoughts about this?

Reference:

Kim, H., Heo, H. I., Kim, D. H., Ko, I. G., Lee, S. S., Kim, S. E., … Kim, C. J. (2011). Treadmill exercise and methylphenidate ameliorate symptoms of attention deficit/hyperactivity disorder through enhancing dopamine synthesis and brain-derived neurotrophic factor expression in spontaneous hypertensive rats. Neuroscience Letters. https://doi.org/10.1016/j.neulet.2011.08.052

Oliver Grimm is a senior psychiatrist at the University Hospital Frankfurt where he is responsible for the adult ADHD outpatient clinic and is involved in the CoCA-project ( www.coca-project.eu ).

Most people consider the tube maps of big cities e.g. London’s tube map complex and irritating.

On the other hand, people immediately spot patterns in most tube maps. Most often, you recognize a limited number of hubs e.g. the central station. If the central station is left out, traveling gets much harder. A tube map is a compromise between a completely random net between nodes (or call it stations) and a simple, extremely hierarchical one. tube-map

Mathematicians call this a small network and developed a whole theory for better characterization of the lines and nodes (vertices and edges, in the mathematicians’ slang).

So, what has this to do with ADHD? If brain connectivity plays a role for attention and better organization of your behavior, maybe the “tube map” of an ADHD patient is not efficiently organized. This could be analyzed by measuring the brain’s activity in several regions over time and then correlating these timecourses to look which regions are tightly linked (form connections) and which regions are not (no “subway connection available between these regions”). Than one could use this theory for characterizing the brain network. That’s exactly what Robert Cary and colleagues report in the Journal Cerebral Cortex (2016;1–10; doi: 10.1093/cercor/bhw209).

They investigated 22 patients with ADHD with and without their medication and compared it to the network pattern of 31 controls.

For this, they calculated for each point in the resting-state data of the brain (so-called “voxel”) a measure they termed “node dissociation index” (NDI). The basic idea is that for a part of the brain nodes, we can define a “module”. A module for a given node is its number of links to different nodes in relation to the sum of all links (a bit more complicated, but that’s the basic idea). The Modularity in a region is the sum of the modularity of all nodes in this region. The node dissociation index is the sum of all modules in relation to the number of connections (in the specific node i and across all nodes).

When we look at the nodes number 1,5 and six, we see two highly interconnected networks in green and blue. These form two different “modules”. While node 1 has three connections to 2,3, and 4, it does not connect to the blue module, therefore its NDI is zero. Node number six is highly connected within the blue module but not to the green module, its NDI is zero. Node number 5 has four connections and one connection to the green module, therefore its NDI is 0.25.

ndi-example

In the analysis by Cary et al. the NDI (summed for specific networks like “visual”, “default mode” or “salience” ) takes values between 0.1 (visual) or almost 0.7 (salience). These measures give us a clue how tightly these networks are linked to nodes within their own communities (low dissociation indices) or whether they “dissolve” their connections and have connections to nodes which are not grouped into their own node community.

What was the effect when patients were scanned after having had a short medication wash-out? And how does this compare to the healthy controls?

The controls had lower values of the dissociation index than the patients. In patients, the visual system was not affected (very plausible!), but a variety of networks showed a decrease of the dissociation index when patients were on medication. The largest differences in networks were found in the visual attention network, the salience network and the fronto-parietal network. These networks are involved in higher order cognitive functioning and mediate psychological functions which are implicated in ADHD. The interesting take home message is, that by giving stimulant medications to patients a confuse and badly organized “tube map” (or brain network) gets a more concise structure. Graph theory offers an interesting perspective on brain networks. Future work might look in detail at how clinical phenomena are connected to brain networks or how specific comorbidities (e.g. additional addiction disorders) influence brain networks.