Biological states associated with mental and brain health
Mental and brain disorders are often associated with altered biological states.
In the previous step we discussed the close links between mental and physical health.
This could be explained by several common biological alterations that underline many mental and physical conditions.
One crucial factor that supports mental health is brain plasticity. Brain or neuro plasticity is the ability of the brain to alter its connections, greatly affecting its overall functions.
The human brain has the capacity to re-wire itself and even form new neurons. This ability is important during the brain development and maturation in early life and supports brain structure and function throughout life. Brain plasticity is also critical in later life to moderate cognitive decline.
The process of neurogenesis (ie growth of new neurons) is at least partly dependent on a protein called ‘brain derived neurotrophic factor’ (BDNF). BDNF is present in most parts of the brain, particularly the hippocampus – the area responsible for mood and cognition.
Interestingly, experimental and observational studies show decreased levels of BDNF in stress, serious mental illness and in neurodegenerative disorders, indicating impaired brain plasticity. Similarly, decreased levels of BDNF and smaller hippocampal volumes have been repeatedly associated with poor diet, linking concepts of diet and brain plasticity. Experimental studies in animals also show that diet has a significant impact on BDNF levels and memory functions that are dependent on the hippocampus.
Oxidative and nitrosative stress
Oxidative and nitrosative processes are chemical reactions that involve oxygen or nitrogen molecules. These processes are part of normal physiological function of living organisms.
However, oxidative and nitrosative stress leads to imbalance between antioxidants and free radicals, accelerating cell damage and negatively impacting immunity and other biological processes.
Evidence shows a relationship between the markers of oxidative stress and depression; individuals with depressive symptoms often present with a lower antioxidant capacity and greater levels of oxidative stress markers than those without depressive symptoms.
Results of experimental animal studies also suggest that accelerated oxidative and nitrosative stress may play a key role in progression of depression.
Oxidative stress is also thought to play a role in other mental disorders such as schizophrenia. However, the exact mechanisms behind this association as well as possible preventative and treatment strategies based on this understanding are yet to be clearly established.
Nutritious diets high in various colourful plant foods such as fruit and vegetables deliver a great abundance of dietary antioxidants, which may help reduce oxidative and nitrosative stress.
The complexity of biological alterations associated with poor mental health present many challenges to prevention and management, highlighting the critical importance of acting on modifiable factors, such as diet.
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