Diversity and equality are two buzzwords often heard in conversations about pay, human rights, and more – and for good reason. In many areas, the human race has such a long way to go. But according to Dr Michael Hall, a world-leading chiropractor and functional neurologist, the healthcare industry is one where diversity has not yet been fully acknowledged or catered for. In the majority of healthcare practices, we don’t acknowledge and understand the sexual dimorphism of the human brain, or how this in turn affects stress, physiology, and symptomology.
Spinal Research caught up with Dr Hall, friend of the Foundation and the man behind the new education offering Brain DC, to talk about this important issue. Before we delve into the detail of this topic – a disclaimer is necessary: this is not a commentary on social issues, or issues of gender or sexual diversity. This is about the neurology that drives us, how it differs between biological sexes, and why we need to adjust our practice to best serve it.
A number of studies over the years have yielded different answers to the question, “are male and female brains different?” In 2015, a massive study looking at MRI scans arrived at the conclusion that human brains couldn’t be categorised into two distinct classes of ‘male brain’ or ‘female brain.’ [1].
Yet the big science of the brain connectome is revealing another reality: that there are fundamental differences in the way the hemispheres of the brains fire. This, according to Dr Hall, results in significant differences in disease tendencies, the core needs that must be met in order to maintain wellbeing, and in the way males and females should be treated and assessed.
“Every student in med school goes through studying conditions,” he points out. “No student out there would argue with me that females aren’t more affected by migraines than are males. And if we look at Alzheimer’s, it’s clearly a disease that affects women more than men.” He then points out that disorders of dopamine, such as ADHD (Attention Deficit Hyperactive Disorder) or Parkinson’s Disease, tend to afflict males more than females.
These are but four examples of a certain condition landing more heavily on one sex than the other – and Dr Hall has plenty more where they came from. He explains (to a female Spinal Research writer) the difference between the brains, and why it matters for practitioners:
“The connectome is about understanding how the functioning areas of the brain connect to one another. Females have a totality of a fewer number of neurons, but you have more connections and those connections are more inter-hemispheric. So the female brain has connections from both the right and left side. As much as it pains me to say it, you have a far superior brain to what I do.
If we look at stroke cases, most of us have memorised that the language centre is on the left side of the brain, but the female has language on the left and right. So if a female patient had a stroke affecting the left side, she would recover much better in the language centres than a male.”
Strokes might be an obvious case where the female brain could respond differently to rehabilitation, but Dr Hall explains that the differences between the brains start way back at the beginning, and cause each gender to have definite requirements that must be met.
When boys and girls first present at school, educators will notice a significant difference in the strengths of each gender. Generally speaking, girls are far more advanced in their verbal and language skills, whereas boys tend to lag behind them in this area. Yet the boys have their own areas of strength in spatial orientation. As they grow, the genders remain different. Most females will have less body mass (lean muscle mass and bone density) than a corresponding male.
Why does this matter? Because it is reflective of brain activity and development. Boys, generally speaking, may lag in verbal skills but Hall illustrates that this is because physicality is a requirement of males more-so than females. It is so, because of the hormone that makes the most difference in utero and through-out the life cycle – testosterone. Females, who have progesterone rather than testosterone as a key hormone, have different requirements for stress relief and wellbeing.
“A young 16-20 year old boy should be able to bench press 200-300 pounds,” says Hall. “A young girl should not, unless she has chosen to go a different route. Now if you study the spectrum, which sex is diagnosed far more frequently with ADHD? Boys are – because they are lagging in verbal skills. Men are more physical. As a male, I require physicality to maintain muscle mass and bone density. That is why I have testosterone as a primary hormone. Women don’t have that. They have progesterone as a primary hormone. She needs to be more verbal, more socially connected. She requires that engagement to be fulfilled.”
The male brain, simply by being male, is more prone for Parkinson’s (a disorder of dopamine) and ADHD (also a disorder of dopamine). Females are 
more at risk for Dementia, Alzheimers, chronic pain and so on.
Yet because we don’t fully acknowledge the diversity in the brains and physiologies of the sexes, we don’t cater our assessment differently. We don’t measure the male patients physical fitness or activity levels. We don’t say ‘this is the type of physical activity you need and how often.’ We simply adjust and send him back to his desk job, and a lifestyle that increasingly allows for declining testosterone levels due to lack of adequate physical activity and other stressors. Nor do we acknowledge the profound affect that social isolation could have on a female, or the positive affect that social support and stability can have on her wellbeing.
This isn’t a generalisation made without the backing of science. “If we study the anterior hypothalamus, the interstitial nuclei (the third nucleus of the interstitial nuclei of the Anterior Hypothalamus) is the sexually dimorphic nucleus. All babies come from the female template. What makes me male, as opposed to female, is testosterone. As a young boy, the thing I require to grow my brain is [physical] activity.”
But Hall is quick to make a distinction that shouldn’t be missed: “The key word is ‘require’. Here’s where people struggle – This does not mean girls can’t be active and physical. It just means boys require it.“ The same can be said for the female need for social connectedness. This does not mean that all females are extroverts. It just means they need quality connection in some form.
There’s a lot to be unlocked from the way the brain develops in utero. For the first couple of years, the right side of the prefrontal cortex is developing, and then from 2-6, the left brain is developing. “There’s a left to right orientation,” says Hall before giving a brief overview of what lies on each side. On the right side, which is more ipsilateral in function, we have more sympathetic functions. The left side is more parasympathetic, but only if the right is functioning well. So the right-brain sympathetic function of heart rate is linked to the left-side function of ventricular pressure. There’s a difference in the way males and females will respond to a stressor that affects the cardiovascular system.
“Heart disease world-wide is the #1 killer of man. But it is a chronic illness it is not due to pathology. Now we could posit that maybe its stress that no one is talking about that is taking a toll on your heart. But now, heart disease in women is almost equal to in men. But women go more to the tachycardia and take beta-blockers, and men go more to the antihypertensive side and taking those medications. Women tend to have more arrhythmias. Men tend to go down the road of more heart failure and cardiomyopathy.”
It’s important to note that left to right orientation topic isn’t without its pitfalls. In fact, it can lead to a line of conversation that Hall believes needs to go away. He argues that, “It’s not that you are female so you are right brained and I’m male so I’m left brained. That line of discussion needs to go away because you are just as capable of working from both sides.” The idea is that the male brain has more neurons but the female brain has more connections across the corpus callosum. The male brain is more intra-hemispheric and mechanistic , thus needing details and statistics to make decisions. The female brain is more inter-hemispheric, allowing for more intuitive decision-making. “It’s a far healthier place to be,” he says (a win for the ladies!)
The cardio issue is just one sexually dimorphic issue that needs bringing out in clinical practice. One article is simply not long enough to talk about all the other health issues that manifest differently according to the patients biological sex. In fact, its a subject so broad that Hall has created the Brain DC education program to address the significant issues that need to be brought out in clinical practice.
Stay tuned for part 2 of our Michael Hall series where he discusses why we need to change our assessments to reflect the sexual dimorphism issue and its physiological and neurological effects.
References
[1] Joel D, Berman Z, Tavor I, Wexler N, Gaber O, Stein Y, Shefi N, Pool J, Urchs S, Margulies D, Liem F, Hanggi J, Jancke L and Assaf Y (2015), “Sex beyond the genitalia: the human brain mosaic,” Proceedings of the National Academy of Sciences of the United States of America, http://www.pnas.org/content/112/50/15468 retrieved 29 March 2017
[2] Hall M, McIvor C (2017), “Interview with the Australian Spinal Research Foundation,” Personal correspondence. Video available by request to members only.
Bibliography
[3] Teaching the Female / Male Brain – Abigail Norfleet James
[4] Scientific American – A Success in the Fight Against Alzheimer’s; April 2017
[5] Laterality: Asymmetries of Bordy, Brain and Cognition. 2013 http://www.tandfonline.com/doi/abs/10.1080/1357650X.2011.631545
[5] Nature Neuroscience. 2015, http://www.nature.com/neuro/journal/v18/n10/full/nn.4113.html
[6] Bakhtadze M, Vernon H, Karalkin A, Pasha S, Tomashevskiy I, Soave D, (2012) “Cerebral Perfusion in patients with chronic neck and upper back pain: preliminary observations,” J Manipulative Physiol Ther 2012;35:7
[7] “Cerebral Metabolic Changes in Men After Chiropractic Spinal Manipulation for Neck Pain,” J Alternative Therapies, Nov/Dec 2011, Vol 17, No. 6
[8] “Chronic back pain is associated with decreased prefrontal and thalamic gray matter density,” J Neuroscience, Nov 17 2004
[9] Hitt E (2010) “Walking Maintains Brain Volume, Prevents Cognitive Impairment,” J Neurology, 2010; 75:1415-1422
[10] “Prenatal stress increase anxiety related behavior and alters cerebral lateralization of dopamine activity,” J Life Sciences, Volume 42, 1988 pp. 1059-1065
[11] Dabbs J, (1980), “Left-Right Differences in Cerebral Blood Flow and Cognition,” J Psychophysiology, 17: 548-551
[12] “Insensitivity to future consequences following damage to human prefrontal cortex,” J Cognition, 1994 Apr-Jun; 50 (1-3):7-15
[13] Shammi P, Stuff T, “Humour appreciation: a role of the right frontal lobe,” J Brain, 1999; 122 (4): pp 657-666
[14] Medina, J (2010) “Brain rules for baby,” Pear Press
[15] Tanaka et al. (2011), “Autonomic nervous alternations associated with daily level of fatigue,” Behavioural and brain functions, 2011, 7:46 http://www.behavioralandbrainfunctions.com/content/7/1/46
