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Is ‘mental illness’ in the mind, or the body… or both?

8 January 2024

In last week’s post, Worried sick, I briefly mentioned a study which examined markers of both brain and body health in people diagnosed with any of four neuropsychiatric conditions, and found that they had greater deviations from healthy controls in markers of body health – most notably in their metabolic, hepatic, and immune systems – than in markers of brain health.

This study, titled ‘Evaluation of Brain-Body Health in Individuals With Common Neuropsychiatric Disorders‘, is interesting both for what it reveals about the physical health of people diagnosed with (so-called) mental illness, and what it fails to discuss. Let’s dig into it together.

Researchers from a number of Australian universities and medical research centres obtained biometric data on brain and body health from almost 86 000 adults diagnosed with one or more “common neuropsychiatric disorders” – schizophrenia, bipolar disorder, depression and generalised anxiety disorder – and a roughly equal number of healthy controls (i.e. people who had never had any of these diagnoses), matched for age and sex.

All participants were enrolled in one of the following population-based neuroimaging biobanks based in the US, UK, and Australia:

  • UK Biobank
  • Australian Schizophrenia Research Bank
  • Australian Imaging, Biomarkers, and Lifestyle Flagship Study of Ageing
  • Alzheimer’s Disease Neuroimaging Initiative
  • Prospective Imaging Study of Ageing
  • Human Connectome Project–Young Adult
  • Human Connectome Project–Aging.

The researchers used brain imaging data on grey matter and white matter volume, obtained from magnetic resonance imaging (MRI) scans of participants without any neuropsychiatric illness or other serious medical conditions, to establish sex-specific normative reference ranges for brain health across the adult life span.

Likewise, they used data from physical assessments and blood and urine sample assays of UK Biobank participants, to establish normative ranges for biomarkers of the health of seven body systems: pulmonary, musculoskeletal, kidney, metabolic, hepatic, cardiovascular, and immune.

In all, the researchers established normative reference ranges across the adult life span for 203 imaging, blood, urine, and physiological markers of brain and body health.

Then they compared the brain scans and physiological health markers of people diagnosed with schizophrenia, bipolar disorder, depression and generalised anxiety disorder, to the norms they had established for the healthy controls. What they found was fascinating, and enormously challenging to the typical framing of ‘mental illness’: People diagnosed with any of the four neuropsychiatric illnesses, deviated more from the healthy reference ranges in markers of body health than in brain health. That is, their bodies were more obviously sick than their brains.

Looking first at markers of body health, the researchers reported:

“We found that all organ-specific health scores were on average significantly lower in individuals with neuropsychiatric disorders compared to age- and sex-matched healthy peers.”

Evaluation of Brain-Body Health in Individuals With Common Neuropsychiatric Disorders

The metabolic, hepatic (liver), immune and kidney systems showed the most deviation from healthy norms. The poorest body health scores were found in schizophrenics, followed by people with bipolar disorder, depression, and generalised anxiety disorder.

Turning to markers of brain health, “subtle structural brain changes” were noted in people diagnosed with bipolar disorder, depression and generalised anxiety disorder, but the researchers rated their brain health as only marginally worse than that of healthy controls. Schizophrenics had the poorest brain health, but the differences between them and the healthy controls were described as “small to moderate”.

In summary,

“Body health was on average poorer than brain health in these patients, which may be partly explained by physical comorbidities.”

Evaluation of Brain-Body Health in Individuals With Common Neuropsychiatric Disorders

The researchers were able to develop diagnostic classification systems that accurately differentiated people with schizophrenia, bipolar disorder, depression, or generalised anxiety disorder from healthy controls, on the basis of differences in markers of body health. To their own evident surprise, these were more accurate than classification systems based on brain imaging. However, brain-based diagnostic classifications outperformed body-based classification systems when it came to differentiating between neuropsychiatric diagnoses (e.g. distinguishing a person suffering from schizophrenia, from a person with bipolar disorder).

Why are people with neuropsychiatric diagnoses so physically unwell?

The researchers decry the lack of attention paid to the body health of people diagnosed with (so-called) mental illness, despite the known high rates of physical comorbidities:

“Mental illness is associated with higher rates of chronic physical illness, including coronary heart disease, obesity, and diabetes,1,2 compared to the general population. This contributes substantially to the global health and economic burden due to increased morbidity, disability, and mortality.3,4 Yet in psychiatric care and services, physical health has been neglected and inadequately managed for decades.”

Evaluation of Brain-Body Health in Individuals With Common Neuropsychiatric Disorders

They blame a number of factors for this neglect:

“Poor physical health in patients is likely underestimated due to existing disparities in health care for people with mental illness, such as lack of access to adequate primary care,7 diagnostic overshadowing,8,9 and difficulties with acknowledging10 and reporting medical problems for some patients.11,12

Evaluation of Brain-Body Health in Individuals With Common Neuropsychiatric Disorders

And finally, they summarise the implications of their findings as follows:

Meaning  Management of serious neuropsychiatric disorders should acknowledge the importance of poor physical health and target restoration of both brain and body function.”

Evaluation of Brain-Body Health in Individuals With Common Neuropsychiatric Disorders

“Restoration of both brain and body function.” Doesn’t that sound marvellous? And completely antithetical to the theory and practice of orthodox medicine. Psychiatric medications are, as Dr Peter Breggin has described in great detail, brain-disabling. And as I discussed in Stop calling them ‘side effects’, the vast majority of pharmaceuticals prescribed for physical ailments ‘work’ by interfering with body functions, not “restoring” them.

Furthermore, the study authors failed to mention the fact that psychiatric medications are well known to cause derangements in physical function, including in the body systems which they identified as furthest from healthy norms in participants with neuropsychiatric diagnoses (metabolic, liver, immune and kidney). For example:

I find it impossible to believe that the authors of this study are unaware of the voluminous research on adverse effects of psychiatric drug use. So why did they not even explore the possibility that at least some of the impaired body function that they identified in participants with neuropsychiatric diagnoses was actually iatrogenic (treatment-induced), rather than an intrinsic component of the (so-called) mental illness?

If I were the cynical type, I might suspect that at least some of the authors – especially those linked to QIMR Berghofer, which develops drug and biologic candidates for commercial release – are preparing the ground for the development of new, biologically-based, therapeutic agents for treatment of neuropsychiatric conditions. But who could be that cynical?

All that said, it is undeniably the case that so-called mental illness is not a discrete entity, confined to the minds of sufferers. It has, at the very least, biological correlates. For example,

“Abnormalities in glucose regulation were first reported in patients with schizophrenia and bipolar disorder prior to the introduction of antipsychotic medication, with early reports5,6 indicating a pattern of insulin resistance in untreated patients.”

Metabolic Changes Associated With Antipsychotic Use

And, as I wrote in Rumination Inflammation, there is a strong link between systemic (body-wide) inflammation and depression:

“Levels of inflammatory chemicals such as tumor necrosis factor-a (TNF-a), interleukin-6 (IL-6), interleukin-10 (IL-10), and C-reactive protein (CRP) have been found to be elevated in depressed people (3), with the highest levels seen in those contemplating suicide (4).”

Rumination Inflammation

So we know that people with neuropsychiatric diagnoses also have significant impairments in their physical health; we know that at least some proportion of these impairments is intrinsic to their so-called mental illness, and some proportion to the adverse effects of the psychiatric drugs prescribed to them.

What other factors might be at play?

1. Poor diet quality

As I’ve discussed at length in many previous articles (e.g. The good news about depression – Part 1, Eat your way to better mental health?, Good mood food and The evidence is in: Eating better relieves depression), dietary practices have a major effect on our psychological well-being. Specifically, diets high in fruits, vegetables and other minimally-processed plant foods are protective against the development of depression and anxiety, and show promise in promoting remission in people who have already developed these conditions.

Unfortunately, people with neuropsychiatric diagnoses tend to have less healthful diets than people who don’t, due to disordered eating behaviours, poor executive control, medication-driven appetite increase, and low food security linked to reduced income.

Which came first: the poor diet, or the neuropsychiatric condition? Or are they mutually reinforcing? My guess is the latter option. In any case, the same poor dietary quality associated with heightened risk for so-called mental illness is also a driver of bodily illness.

And that prompts an important question: is so-called mental illness simply a manifestation of disturbed physical function? I strongly suspect that it is, and that certain people are predisposed to manifest emotional, cognitive and psychological symptoms of disturbed physical function, as a consequence of…

2. Personality factors

Personality is highly heritable (i.e. linked to genes inherited from one’s parents), quite stable across the life course, and associated with differences in neurotransmitter activity – that is, it has a neurobiological basis.

Certain personality traits are strongly linked to the development of neuropsychiatric illness; for example, low conscientiousness is linked to depression, anxiety, schizophrenia and bipolar. And personality is strongly associated with health status; for example, low conscientiousness is also associated with making food choices that result in poor nutritional quality, while high negative emotionality/emotional instability is linked to dysregulation of the hypothalamic-pituitary-adrenal axis.

Pulling all these threads together, and incorporating what I’ve observed in nearly 30 years of clinical practice, this is what I believe is happening:

  • Certain people are predisposed, by dint of genetic factors, to expressing personality traits that leave them vulnerable to developing neuropsychiatric illnesses, as well as to the behaviours (e.g. food choices and substance abuse) that exacerbate those illnesses.
  • Since personality has a neurobiological basis, it stands to reason that it influences biological function ‘below the neck’. In other words, the same genetic factors that shape personality, also affect bodily functions and thereby influence health.

I speculate that in our ancestral hunter-gatherer environment, the negative impacts of these personality traits were mitigated by consumption of a micronutrient- and fibre-rich diet (with limited opportunities to overeat), daily physical activity, the absolute necessity to perform some type of productive work in order to survive, mandatory conformity with a healthy circadian rhythm (no artificial lighting!), and close social ties which ensured prompt attention to manifestations of psychological ill-health and made destructive self-isolation impossible.

Viewed through this lens, the neuropsychiatric illnesses that were the focus of the study I’ve discussed in this post, might be best characterised as manifestations of evolutionary mismatch. No drug, shock treatment or transcranial magnetic stimulation, or patentable biologic substance can ‘fix’ this mismatch. It requires a comprehensive Lifestyle Medicine approach, that incorporates attention to diet, exercise, circadian rhythm, social connection, cultivating a sense of purpose, resolution of past trauma, and usually, very careful tapering of brain- and body-impairing psychiatric medications. As far as I am aware, the “restoration of both brain and body function” that the authors call for, cannot be achieved by any other means.

Agree? Disagree? Comment below!

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