Interplay of genetics and loneliness
Interplay of genetics and loneliness
The Neuroendocrine System
The
HPA Axis
The stress response is controlled by the HPA axis, or the Hypothalamus-Pituitary-Adrenal axis. In the presence of a stressor - whether that is an impending deadline, immediate threat, or loneliness - the body releases hormones in the brain. It further activates other physiological responses that are meant to protect us from that threat. However, when that threat does not disappear, this stress response becomes detrimental.
How does the HPA axis work?
1.
The hypothalamus is activated by the presence of a stressor, such as loneliness.
2.
The hypothalamus releases hormones that activate the pituitary gland.
3.
The pituitary gland releases a secondary hormone that activates the adrenal gland via the bloodstream.
4.
The adrenal cortex releases cortisol, which activates downstream physiological responses to reduce the stressor.
5.
Once the stressor passes, negative feedback turns off activation of the hypothalamus.
What are the downstream effects and their potential health implications?
INCREASED HEART RATE
Increased heart rate increases oxygen supply to our body, enhancing our functioning capacity.
​
HOWEVER, if our heart rate is constantly increased, our blood vessels become thickened to compensate for the increase in blood pressure. Consequently, our heart has to continually work harder and harder.
This increases risk for atherosclerosis and more severe cardiovascular dysfunction.
INCREASED BREATHING RATE
Increasing our breathing rate increases not only our oxygen intake, but our carbon dioxide exhalation rate. This allows us to increase functioning of the rest of our body without accumulating toxic gas.
​
HOWEVER, if our breathing rate is constantly elevated due to chronic stress, the body puts greater stress on the heart to distribute oxygen and expel carbon dioxide.
​
This increases our risk of respiratory concerns and cardiovascular issues.
DECREASED DIGESTION
To conserve energy, the body temporarily halts digestive processes. This increases our available energy reserves during times of crisis.
​
HOWEVER, if our body is continually putting digestive processes on hold, the makeup of our gut microbiome may become permanently altered.
​
This increases risk for digestive concerns, including that of the gut microbiome.
DECREASED IMMUNE FUNCTION
Cortisol decreases immune functioning during times of stress to conserve energy and resources. The body shouldn't need the immune system to flee from threats, and so it becomes suppressed.
​
HOWEVER, continuous suppression of the immune system is detrimental to our health. It decreases our ability to fight infection, make antibodies, and launch an immune response.
​
This increases risk for contracting viruses, illness, and infection while also increasing our risk for autoimmune diseases.
Thus, there are physiological changes in response to stress that may have detrimental consequences to our physical and mental health. Loneliness can act as a chronic stressor, triggering these outcomes in older individuals that are experiencing social isolation. Because older individuals already have compromised immune systems, lower heart functionality, or lower overall health, these other health complications may be fatal.
​
We see that it is important on a biological level to give older patients the resources and technology to manage their loneliness and depressive symptoms that result to prevent chronic stress response activation.