Bipolar disorder has a strong genetic foundation, with heritability estimates ranging from 60% to 85% based on twin and family studies. While no single gene is responsible, multiple genetic variations affecting neurotransmitter regulation, circadian rhythm signaling, and neuronal plasticity collectively increase vulnerability to mood dysregulation.
At the neurochemical level, bipolar disorder involves disrupted balance among serotonin, dopamine, and norepinephrine systems. During manic episodes, dopamine activity surges, driving the characteristic euphoria and impulsivity. During depressive episodes, serotonin and norepinephrine signaling diminishes, leading to the profound low mood and loss of motivation that patients experience.
Research has also identified structural and functional differences in the prefrontal cortex and amygdala of individuals with bipolar disorder. These brain regions, responsible for emotional regulation and impulse control, show reduced volume and altered connectivity, which helps explain why mood episodes can feel so difficult to manage without professional treatment.
