A diminished sense of smell could be a symptom of something as harmless as a seasonal allergy, or it could be a sign of a heightened dementia risk. People who become visually or hearing impaired often find ways to maintain a wonderful quality of life, while others find those sensory changes isolatingÑa life change that can lead to depression and other problems.
When all your senses are working properly, you may not give them much thought. But when one of them starts to change, it’s important to pay attention and consult a doctor. And while impaired vision or hearing should prompt a visit to specialists in those fields, losing your sense of smell, for example, may be more puzzling.
Zeina Chemali, MD, MPH, director of Neuropsychiatry Clinics at Massachusetts General Hospital, says that if you notice a reduction in your sense of smell, you should first consult your primary care physician if the change can’t be accounted for by allergies, an acute upper respiratory infection, or obstructive sleep apnea. “A progressive decrease in a sense of smell has been linked to neurodegenerative diseases, such as Alzheimer’s disease and Parkinson’s, as well as the low likelihood of a tumor around the olfactory nerve or orbitofrontal region of the brain,” she explains. “A referral to a neurologist would help with a detailed assessment.”
The Nose Knows
Your sense of smell can provide you a lot of information, some of it pleasant (orange blossoms in bloom), and some of it dangerous (smoke from an electrical fire). When you lose part of your sense of smell, it’s known as hyposmia. Total loss is called anosmia. These changes may be temporary or permanent, depending on the cause.
WHAT YOU CAN DO
- Have your hearing checked every three to five years as part of your regular physical exam, unless you notice a change in your hearing. Then see an audiologist as soon as possible.
- Have your vision checked every one to two years depending on whether you wear corrective lenses or have other eye health concerns. If you notice any change in vision, see an ophthalmologist soon. Vision loss caused by a condition such as a detached retina may be preventable if treated promptly.
- Tell your primary care physician if you notice any changes in your senses of smell, taste, or touch.
- Remember that a wide range of health conditions, medical procedures, medications, and age can affect your senses, so be sure to consult your health-care providers before you jump to conclusions about your sensory concerns.
Nasal congestion is the most common cause of a reduced sense of smell. Aging can also be a benign cause. Smell works when tiny particles from a source (pine needles, a gasoline tank, etc.) are inhaled and attach to receptors in the mucus membranes in your nose. This stimulates nerves that send signals directly to the olfactory center of the brain. Damage to those nerves is how losing your sense of smell can be a sign of a neurological disorder. In addition to Alzheimer’s and Parkinson’s, other conditions and even some medical procedures can trigger a change in your olfactory system. Among them are:
- Multiple sclerosis
- Huntington’s disease
- Brain aneurysm
- Zinc deficiency
- Brain surgery
- Radiation therapy
Some medications, including blood pressure-lowering drugs, may also affect your sense of smell. It’s worth noting that most cases of anosmia or hyposmia are not related to neurological conditions. Polyps in the nose or some other treatable problem are usually to blame.
Regardless of the cause, especially if you don’t know what it is, you should see a doctor when you become aware of a change.
Taste and Touch
Your sense of taste is directly affected by your sense of smell, so olfactory changes can lead to a decline in how well you enjoy your favorite meal. Taste and smell are part of your chemical sensing (chemosensation) system, and they rely on similar receptors to send signals to your brain.
So while some of the previously mentioned causes of anosmia or hyposmia can also affect taste, factors such as age, smoking, certain medications and cancer treatment can also affect your taste buds, either by reducing your sense of taste or by causing an unpleasant taste to linger in yourÊmouth.
Along with making meals disappointing, a loss of taste can cause some people to eat less, raising the risk of malnutrition and unhealthy weight loss. “Enjoying food is one of the most primitive, yet most rewarding feelings,” Dr. Chemali says. “Inability to taste and enjoy food could, of course, lead to severe cases of frailty in the elderly, but it often and more commonly impacts negatively one’s quality of life.”
Also drastically affecting quality of life is change in your sense of touch, also known as tactile perception. The inability to sense heat, cold, touch, pain, and other stimuli is often associated with major nerve fiber damage or injury to the spinal cord. Numbness in your extremities may be caused by a spinal cord injury or by localized nerve damage, such as diabetic neuropathy that might affect the nerves in your feet, for example.
“The sense of touch is less talked about in research, although a complete loss of temperature sensitivity could cause burns, and a loss of proprioceptive sense (how your body responds to changes in position and motion) is one of the leading causes of gait instability in older adults, increasing their risk for falls,” Dr. Chemali says.
Seeing, Hearing, and Interacting
The effects of declining vision and hearing can also impact many parts of your life, including your risk for falls and other injuries. Impaired vision can limit or end your ability to drive safely, for example, while hearing impairment can make even one-on-one conversations a challenge.
For many people corrective procedures and devices can often offset those sensory declines. However, when the changes aren’t correctable or aren’t treated effectively, the result can be social isolation and its unfortunate consequences.
Isolation is a major risk factor for depression, as well as other medical concerns. If food shopping, doctor appointments, and other necessary functions become too difficult, you can develop serious health problems. You also risk losing your independence.
“Sensory deprivation of any kind, but especially vision and hearing, leads to decreased interaction with one’s environment and a sense of isolation,” Dr. Chemali says. “One cannot get the information if, in the first place, that information was not encoded because it wasn’t caught by the sensory threshold. Sensory deprivation is easily preventable with annual prevention vision and hearing tests, and with the use of remediation and correction, such as glasses, lenses, cataract surgery, etc., in the case of vision impairment, as well as hearing aids in the case of hearing loss.”