Diminished Sense of Smell Linked with Depression

There is nothing like the smell of freshly brewed coffee or bread baking in the oven to invoke happy memories and contentment.  Our sense of smell is closely tied with memory, and a pleasant aroma can lift spirits, increase enjoyment of food, and even calm a busy mind.  But some older adults experience a decline in their ability to smell – a condition that has been linked with an increased risk for neurodegenerative diseases, as well as depressive symptoms. 

According to a recent US News HealthDay report, researchers have found a new link between a diminished sense of smell and a greater likelihood of developing depression.   Study participants were healthy older adults between the ages of 70 and 73 who had no difficulty walking, climbing stairs or performing normal activities.  The participants were assessed in person annually and by phone every six months. 

At the outset of the eight-year study, 48 percent of participants had a normal sense of smell, 28 percent showed a decreased sense of smell, and 24 percent had a profound loss of olfactory sense.  Roughly 25 percent of participants developed significant depressive symptoms during the follow-up period – those with decreased or significant loss of the sense of smell had an increased risk of depression.  

Losing one’s sense of smell can not only be dangerous to health because we rely on smell to alert us to something burning, a gas leak, or spoiled food.  But scent is also closely linked with taste, and people who cannot smell well may find their enjoyment of food is diminished, and they are less connected with the world and people around them. 

Olfactory neurons, located in the nose, pick up molecules released by substances and the odor receptor relays this smell to the brain’s olfactory bulb where it is processed.  Researchers believe this region of the brain works closely with the amygdala, hippocampus and other brain structures involved with memory, decision-making and emotional responses.  Scientists suggest that smell and depression may be linked both behaviorally – with reduced social interaction for example, and biologically through factors such as decreased serotonin levels. 

The research demonstrates a connection between loss of smell and depression, and diminished olfaction in older age could be considered a predictor of late-life depression.  Learn more about how smell can change in older age by following this link to National Institute on Aging.