We all learned about our five senses when we were children: vision, hearing, taste, smell, and touch. And it is easy enough to understand what happens when one or more of those senses becomes impaired.
But functional loss of any of these senses is not exactly catastrophic to brain function. Blind people can still find their way around a room and deaf people can still communicate with others. The point is, interruption of one of the five primary senses results in pretty good compensation by all the others.
The proprioceptive sense is the part of the nervous system that integrates the input from those five senses to create meaning of the environment and your place in it. Proprioception is a huge component of normal development, and a huge component of reverse development (aka Alzheimer’s).
Here is the formal definition of proprioception:
Perception of stimuli relating to position, posture, equilibrium, or internal condition. Receptors (nerve endings) in skeletal muscles and on tendons provide constant information on limb position and muscle action for coordination of limb movements. Awareness of equilibrium changes usually involves perception of gravity. In humans, gravity, position, and orientation are registered by tiny grains called otoliths moving within two fluid-filled sacs in the inner ear in response to any change in position or orientation. (Merriam-Webster)
The proprioceptive sense is quite dependent on visual-spatial and tactile input to sense up/down/under/over- any position in space. This information is processed in the brain’s vestibular center, which is the area that fails to develop normally in kids with autism. It is also the area in the brain that is particularly vulnerable to many neurodegenerative diseases. As with the treatment approaches seen in sensory integration techniques used with kids, it is important to normalize the neurologically-based sensory systems in order to provide a better foundation for higher level skills acquisition.
Eureka! Let me repeat that: It is important to normalize the neurologically-based sensory systems in order to provide a better foundation for higher level skills acquisition.
Ask yourself: Could you solve a complex math word problem while free falling on a roller coaster? Can you stand on one foot, on a pillow, with your eyes closed, and say the alphabet backwards? It is difficult to engage your brain in higher functions if your body does not feel stable in space, if you don’t have a good sense of where you are in the environment.
So how do we normalize neurologically-based sensory systems in our friends with dementia?
- We put their glasses on them, control glare and shadows, and provide adequate lighting.
- We put their hearing aides in and reduce noise.
- We correct postural deformities and instability to permit access to sensory input.
- We make the ambient temperature comfortable.
- We make sure they are not in pain.
- We adapt the environment to provide sensory input.
Ok, so to the extent possible, we have normalized their sensory systems. Now what?
Now we engage their proprioceptive sense.
- We introduce them to gravity.
- We alter their body positions: head, trunk, and limbs in relation to gravity.
- We provide various sensory input: single sense stimuli and multiple sense stimuli.
- We provide input through their joints in the form of compression and distraction: pushing and pulling (these are natural movements easily elicited in even late stage dementia)
- We have them perform a task that requires the integration of the sense and the output of a movement.
- We spin (gently), rock, roll, and challenge the vestibular sense to equalize under graded challenges.*
- We vary the surface they stand or sit on so that an adaptive response is required.
- We decrease the use of vision to correct postural changes (many falls happen at night when the visual sense cannot be relied on for balance).
The purpose of engaging the proprioceptive sense is to facilitate the integration of all the other senses into an organized motor behavior. So if a person steps from a hard wood floor onto a thick carpet, the change in texture, the color of the floor, the sound of the footstep, and the change in body position will all integrate into a programmed balance response- so the person’s body will be able to adjust to the changes without having to think about what adjustments need to be made.
Many of these techniques are interventions used in pediatrics for sensory processing disorders. *Because older adults have older sensory organs, stiffer joints and muscles, and viscous inner ear fluid (a lesson for another day), we wouldn’t provide the quite the same level of intensity of vestibular experiences due to a variety of risks. However, under the direction of a physical or occupational therapist, vestibular retraining is an effective approach for promoting good proprioception even in the presence of (or especially in the presence of) a neurodegenerative disease like Alzheimer’s.
Healthy adults: keep your vestibular/proprioceptive sense stimulated! Tai chi, dancing, swimming, biking, hiking, climbing, swinging, rowing… challenge your head and body position to keep your proprioceptive sense sharp.