Loneliness is a growing epidemic and an uptick was noted after the onset of the CVOID-19 pandemic. In 2023 the U.S. General Surgeon declared loneliness a public health concern, with Americans aged 18-34 being more likely to experience these feelings, with 30% of this age group saying they experience feelings of loneliness everyday or several times a week.
The ventral tegmental area (VTA) contains dopamine-producing neurons that project to various brain regions. It plays crucial roles in reward processing, motivation, learning, memory, and emotional arousal. Abnormalities in VTA function have been associated with addiction and depression. Upregulation of delta opioid receptors in various parts of the brain is related to chronic pain, chronic inflammation, cancer, and early life adversity. Kappa receptors in the VTA play an integral role in stress, drug seeking behavior, mood and reward, as well as addiction. Previous research has stated that chronic consumption of substances of abuse causes indirect upregulation of the κ-receptor/dynorphin system. It also has been previously noted that the opioid system plays an integral role in regulating the need for social interaction.