The Core Cause: Sensory Mismatch
Motion sickness is caused by a sensory conflict, or mismatch, within the brain. Normally, your brain integrates information from three key systems to understand your body's position and movement: the inner ear (vestibular system), the eyes (visual system), and the body's position-sensing nerves (proprioception). When there is a conflict between these signals, your brain becomes confused, triggering symptoms like nausea, dizziness, and sweating. In older adults, age-related changes can increase the frequency and intensity of this sensory conflict, leading to a worsening of motion sickness.
Degeneration of the Vestibular System
The vestibular system, located in the inner ear, is primarily responsible for sensing head movement and spatial orientation. As with many bodily systems, it naturally degrades with age.
Hair Cell and Neuronal Loss
Research shows a progressive loss of sensory hair cells and neurons in the inner ear as people get older. Specifically, the semicircular canals, which detect rotational movement, can lose up to 40% of their hair cells with age, while the otolith organs, which sense linear acceleration and gravity, also experience cell loss. This reduced cellular function means the brain receives less precise information about motion, making it more susceptible to sensory conflicts.
Benign Paroxysmal Positional Vertigo (BPPV)
BPPV is a common vestibular disorder in older adults, often peaking around age 60, and occurs when tiny calcium carbonate crystals (otoconia) become dislodged and migrate into the semicircular canals. This causes brief, intense episodes of vertigo and dizziness triggered by specific head movements, such as lying down or turning over in bed. The age-related degeneration of otoconia is a major factor in the increased prevalence of BPPV among seniors.
Compromised Visual System
Vision plays a critical role in balance, and age-related visual changes can significantly contribute to motion sickness.
Binocular Vision Dysfunction (BVD)
BVD occurs when the eyes are slightly misaligned, causing the brain to work harder to fuse the two images into a single, clear one. This extra strain can trigger symptoms like headaches, dizziness, and motion sickness. As the eye muscles and nervous system change with age, a subtle BVD can emerge or worsen, increasing susceptibility to motion sickness, especially when reading in a moving vehicle or in visually complex environments.
Reduced Visual Acuity and Contrast
Decreased visual acuity, poor contrast sensitivity, and heightened glare sensitivity are common in older adults. These changes make it harder for the eyes to provide clear, reliable motion cues to the brain. This reduced visual input, combined with a less robust vestibular system, further disrupts the body's overall sense of balance.
Medications and Comorbidities
Many older adults take medications that can directly or indirectly affect the balance system. Common culprits that may cause dizziness and worsen motion sickness symptoms include:
- Antihypertensives (blood pressure medications)
- Antidepressants (SSRIs)
- Anticonvulsants
- Sedatives and tranquilizers
- Certain antibiotics (known to be ototoxic)
Additionally, medical conditions common in older age, such as diabetes, cardiovascular disease, and degenerative neurological disorders like Parkinson's, can contribute to balance issues and increase motion sickness.
Psychological and Central Nervous System Factors
Psychological factors and central nervous system changes can also influence motion sickness sensitivity.
- Reduced Central Compensation: As the brain ages, its ability to compensate for reduced sensory input and adapt to conflicting signals can diminish. While younger individuals can often adapt to repetitive motion, this process may become less efficient with age.
- Anxiety and Fear of Falling: Chronic dizziness and instability can lead to anxiety, which in turn can exacerbate motion sickness symptoms. Fear of falling is a significant concern for many older adults and can create a vicious cycle where anxiety amplifies motion perception, leading to more avoidance and physical deconditioning.
Comparison: Contributing Factors to Motion Sickness
| Factor | Young Adults (Typical Response) | Older Adults (Age-Related Change) |
|---|---|---|
| Vestibular System | Robust hair cell and neuron function, efficient signal processing. | Gradual decline in hair cells and neurons; reduced sensitivity to motion. |
| Visual System | Sharp visual acuity, good contrast sensitivity, efficient eye coordination. | Potential for binocular vision dysfunction (BVD), reduced acuity, poor contrast, and increased glare sensitivity. |
| Brain/Adaptation | Rapidly adapts to and habituates unusual motion, often leading to reduced symptoms over time. | Slower central compensation and adaptation to sensory mismatches; may take longer to adjust. |
| Medication | Generally fewer prescription medications with balance-related side effects. | Higher likelihood of taking multiple medications (polypharmacy) that can cause dizziness as a side effect. |
| Associated Conditions | Fewer co-morbid conditions affecting balance, like diabetes or hypertension. | Higher prevalence of medical conditions that compromise balance and nervous system function. |
What Can Be Done About Worsening Motion Sickness?
Lifestyle and Environmental Adjustments
- Choose your seat wisely: Opt for the front seat of a car or a seat over the wing on a plane, and focus on the horizon.
- Stay active: Regular physical activity, such as walking or specific balance exercises, can help maintain muscle mass and proprioceptive input, supporting overall stability.
- Modify diet: Avoid heavy, greasy, or spicy meals and alcohol before and during travel.
Vestibular Rehabilitation Therapy (VRT)
For persistent or severe motion sickness, a physical or occupational therapist specializing in vestibular disorders can help. VRT is designed to help the brain adapt to and compensate for inner ear dysfunction through targeted exercises, including:
- Gaze stabilization exercises to improve visual focus during head movements.
- Balance exercises to retrain the brain to rely on more stable sensory inputs.
- Motion exercises to gradually desensitize the system to movement.
Medical and Vision Solutions
- Consult a doctor: Review all medications with your physician to identify potential causes of dizziness or motion sensitivity. A doctor can also diagnose underlying conditions like BPPV.
- Consider vision therapy: For cases of binocular vision dysfunction, a neuro-visual optometrist can prescribe specialized prism lenses to correct eye alignment, which may alleviate motion sickness.
Conclusion
While a decline in motion sickness sensitivity is sometimes associated with older age, an increase in symptoms is not uncommon and is often linked to the natural aging of the body's balance systems. The intricate network of the vestibular, visual, and central nervous systems, which once worked seamlessly, can develop subtle degenerative issues, leading to an increase in sensory conflict. Compounding factors such as certain medications and anxiety can further exacerbate the problem. However, by identifying the root cause through a proper medical evaluation and exploring treatments like vestibular rehabilitation or vision therapy, many individuals can effectively manage or reduce their symptoms and regain their comfort and confidence during travel and daily activities. A conversation with a healthcare provider is the best first step to creating a personalized plan for relief.
Visit the Vestibular Disorders Association for more information on managing balance issues.
