Chronic stress, as distinguished from transient stress, continues for a long duration and can have significant impacts on brain function. Chronic stress disrupts the homeostasis of the body and changes essential neurochemical functions that lead to psychological and physiological disorders. Scientific investigations on the neurochemical impacts of chronic stress could explain disorders such as anxiety, depression, and cognitive dysfunction.
The role of the Hypothalamic-Pituitary-Adrenal (HPA) axis
According to Dr Kunal Bahrani, Clinical Director-Neurology, Marengo Asia Hospital, Faridabad, one of the most significant systems influenced by chronic stress is the hypothalamic-pituitary-adrenal (HPA) axis. Chronic stress causes repeated activation of the axis, which translates into repeated high levels of cortisol, the main stress hormone. Cortisol is vital when experiencing acute stress, whereas elevated levels of cortisol in the long run can destroy brain structures, especially the hippocampus, an important location for learning and memory.
Neurotransmitter imbalance
Chronic stress interferes with the balance of these very important neurotransmitters like serotonin, dopamine, and norepinephrine. Low levels of serotonin are most closely associated with mood disorders like depression and anxiety. Dopamine, which controls pleasure and motivation, can also become depleted and cause apathy and loss of pleasure symptoms. Reduced levels of norepinephrine can also enhance feelings of hyperarousal and restlessness.
Effects on brain structure and function
Chronic stress may even change the brain’s structure. The hippocampus atrophies with prolonged exposure to excessive cortisol, and memory and learning capacity decline. The amygdala, responsible for fear and emotion, however, can become overactive, boosting anxiety and emotional sensitivity. The prefrontal cortex, responsible for decision-making and self-control, also breaks down under stress, lessening cognitive flexibility and impulse control.
Inflammatory responses and neuroplasticity
Chronic stress has been linked with higher levels of inflammatory cytokines in the brain. Inflammatory biomarkers have already been demonstrated to disrupt synaptic plasticity, the capacity of the brain to form and reorganise synapses. Reduced neuroplasticity prevents recovery from mental illness and is implicated in the causation of neurodegenerative diseases.
Closure
Chronic stress has deep neurochemical impacts on the brain, affecting all aspects of mood and behaviour, cognition, and even the structure of the brain. Understanding these effects is why stress regulation is so vital to optimal mental and neurological health. Techniques like mindfulness, exercise, and therapy can reverse some of these effects and build resilience.
