Smell is our oldest sense. One of our earliest functions as simple organisms was to detect helpful or harmful molecules in our environment and then seek them out or avoid them. The brain's olfactory bulb still sits alongside regions processing emotion . As a result—although scientists aren't sure of the exact mechanism—dysfunctions of smell are closely associated with mood disorders.
Why Does Scent Develop?
Understanding what causes scent is essential for prevention and treatment. Research consistently shows that scent arises from a complex interplay of biological, psychological, and social factors — rarely from a single cause.
What Researchers Have Found
Research into scent has identified multiple contributing pathways. Studies using neuroimaging, genetics, and longitudinal data reveal that no single factor fully explains why scent develops.
Biological Factors
Biological contributors to scent include:
- Genetics: Family history increases risk; certain genes influence vulnerability
- Brain chemistry: Neurotransmitter imbalances (serotonin, dopamine, norepinephrine) play key roles
- Brain structure: Differences in the prefrontal cortex, amygdala, and hippocampus are documented
- Physical health: Chronic illness, hormonal changes, and sleep disruption can trigger or worsen scent
Psychological Factors
- Early experiences: Childhood adversity, attachment disruption, and trauma shape psychological vulnerability
- Cognitive patterns: Negative thinking styles, perfectionism, and rumination increase risk
- Coping skills: Limited emotional regulation skills make scent more likely under stress
- Personality: Certain traits (neuroticism, harm avoidance) are associated with higher risk
Social and Environmental Factors
Environmental factors — including chronic stress, relationship problems, financial difficulty, and major life events — can trigger scent in vulnerable individuals.
What Triggers an Episode?
Even in people with predisposing factors, scent often requires a triggering event:
- Major life transitions (job loss, relationship breakdown, bereavement)
- Prolonged stress without adequate recovery
- Substance use or withdrawal
- Physical illness or injury
- Social isolation or conflict
Protective Factors
Not everyone with risk factors develops scent. Protective factors include: strong social support, effective coping skills, physical health maintenance, access to care, and psychological resilience built through prior challenges.