The Effect of Exercise on Mental Health: A Focus on Inflammatory Mechanisms.

A growing body of research suggests that neuropsychiatric disorders are closely associated with a background state of chronic, low-grade inflammation. This insight highlights that these disorders are not just localized to dysfunction within the brain, but also have a systemic aspect, which accounts for the frequent comorbid presentation of chronic inflammatory conditions and metabolic syndromes. It is possible that a treatment resistant subgroup of neuropsychiatric patients may benefit from treatment regimens that target their associated proinflammatory state. Lifestyle factors such as physical activity (PA) and exercise (i.e. structured PA) are known to influence mental health. In turn, mental disorders may limit health-seeking behaviors - a proposed "bidirectional relationship" that perpetuates psychopathology. PA is renowned for its positive physical, physiological and mental health benefits. Evidence now points to inflammatory pathways as a potential mechanism for PA in improving mental illness. Relevant pathways include modulation of immune-neuroendocrine and neurotransmitter systems, the production of tissue-derived immunological factors that alter the inflammatory milieu and neurotrophins that are critical mediators of neuroplasticity. In this paper, we will focus on the role of PA in positively improving mental health through potential modulation of chronic inflammation, which is often found in individuals with mental disorders. In a related paper by Edirappuli and colleagues (2020), we will focus on the role of nutrition (another significant lifestyle factor) on mental health. Thus, inflammation appears to be a central process underlying mental illness, which may be mitigated by lifestyle modifications. Lifestyle factors are advantageous as first-line interventions due to their cost efficacy, low side-effect profile, and both preventative and therapeutic attributes. By promoting these lifestyle modifications and addressing their limitations and barriers to their adoption, it is hoped that their preventative and remedial benefits may galvanize therapeutic progress for neuropsychiatric disorders.

The Effect of Nutrition on Mental Health: A Focus on Inflammatory Mechanisms.

Neuropsychiatric disorders are closely associated with a persistent low-grade inflammatory state. This suggests that the development of psychopathology is not only limited to the brain, but rather involves an additional systemic aspect, accounting for the large body of evidence demonstrating co-presentation of mental illness with chronic inflammatory conditions and metabolic syndromes. Studies have shown that inflammatory processes underlie the development of neuropsychiatric symptoms, with recent studies revealing not only correlative, but causative relationships between the immune system and psychopathology. Lifestyle factors such as diet and exercise may influence psychopathology, and this may occur via a bidirectional relationship. Mental illness may prevent health-seeking behaviours such as failing to maintain a balanced diet, whilst adopting a 'healthy' diet rich in fruits, vegetables and fish alongside nutritional supplementation correlates with a reduction in psychiatric symptoms in patients. Obesity and the gut microbiome have proven to be further factors which play an important role in inflammatory signalling and the development of psychiatric symptoms. In a related paper we focus on the role of exercise (another significant lifestyle factor) on mental health (Venkatesh et al. 2020). Lifestyle modifications which target diet and nutrition may prove therapeutically beneficial for many patients, especially in treatment-resistant subgroups. The current evidence base provides equivocal evidence, however future studies will prove significant, as this is a highly attractive therapeutic avenue, due to its cost efficacy, low side effect profile and preventative potential. By promoting lifestyle changes and addressing the limitations and barriers to adoption, these therapies may prove revolutionary for mental health conditions.