Aging and postural control

Models of ageing Two models of ageing (a) The concept that ageing involves a linear decline in neuron function across all levels of the CNS. Primary aging model self limiting perceptions on the part of the older individuals regarding what they can do. (b) The concept that during aging the CNS continues to function well until death, unless there is a catastrophe or disease that affects a specific part of the CNS. Secondary aging model optimistic view.

Interactions between Primary and Secondary factors Primary and secondary factors may interact in the aging process Example: genetic factors can include a genetic predisposition to a specific disease process. Primary factors do not necessarily lead to a generalised decline in function, but rather to a loss of function within specific systems. Secondary factors are more or less under our control. Some of these include nutrition, exercise, insults and pathologies that affect our mind and body.

Continuum of physical function among older adults Physical elitePhysically fitPhysically independent Physically frail Physically dependant Disability Sports competition, senior Olympics Moderate physical work Very light physical work Light housekeeping Cannot pass some or all BADL Dependant in all BADLs High risk and power sports All endurance sports and games Hobbies (walking and gardening) Food preparation Needs home or institutional care Most hobbiesLow physical demand activities Grocery shopping Can pass all IADL Can pass some IADL, all BADLs May be homebound

Behavioral indicators of instability Definition of fall: At clinics: a fall is often defined as a situation in which the older adult fall ground or is found lying on the ground. It is often defined as any unintended contact with a supporting surface, such as a chair, counter, or wall

Activity Objective: To explore issues related to determining fall risk. Procedure: Take a moment and ask yourself how many times you have fallen in the past 12 months. Think about and list the activities you were performing at the time you fell. What were the consequences of your falls? Were you injured? Since the fall, have y0ou been afraid or reluctant to return to those activities? Now, find an older adult living within the community or within a residential facility like an assisted living retirement center or skilled nursing facility. Ask this older adult the same set of questions. What is their fall rate? What activities were they performing when they fell? What was the environment like? Were they injured, and what was the psychological consequence of the fall? Were they more fearful and reluctant to return to their prior level of activity?

Risk factors for falls 11 Risk factors commonly associated with falls among community living older adults: Muscle weakness History of falls Gait deficits Balance deficits Use of assistive device Visual deficits Arthritis Impaired ADL’s Depression Cognitive impairment Age (>80 years)

Falls continued Environmental factors that increase fall risk: Presence of stairs Throw rugs Slippery surfaces Poor lighting

Falls continued Falls are a great risk among hospitalised older adults and those living in residential facilities. Many studies have examined risk factors among hospitalised older adults and consistently Identified the following factors: Gait instability Lower extremity weakness Urinary incontinence / frequency or need for assistance in toileting. Impaired cognition – agitation, confusion, impaired judgement History of falls Use of certain medications, in particular centrally acting sedatives

Risk factor assessment tools Stratify Risk assessment tool for predicting falls in hospitalised elders 1. Did the patient present to hospital with a fall, or has he or she fallen in the ward since admission? (Yes = 1, No = 0) 2. Do you think the patient: (question 2-5) 2.1 Is agitated? (yes = 1; no = 0) 2.2 Is visually impaired to the extent that everyday function is affected? (yes = 1; no = 0) 2.3 Is in need of especially frequent toileting? (yes= 1; no=0) 2.4 Has a transfer and mobility score* of 3 or 4(yes=1;no=0) TOTAL SCORE (range 0-5) score ≥ 2 indicated increased risk for falls

* transfer score: 0 = unable; 1 = major help needed (one or two people, physical aids), 2 = minor help (verbal or physical), 3 = independent. *mobility score: 0 = immobile, 1 = independent with aid/wheelchair, 2 = walks with help of one person, 3 = independent

Risk factors for fall continued Older adults who fall after discharge have a significantly greater decline in independence in ADL and lower performance on balance and mobility measures.

Age related changes in the systems of postural control Musculoskeletal Systems Muscle strength Strength or the amount of force a muscle produces, declines with age. Lower extremity muscle strength can be reduced by as much as 40% between the ages of 30 and 80 years. Muscle strength reduction is more severe in older nursing home residents with a history of falls – the mean knee and ankle muscle strength was reduced twofold and fourfold respectively, compared with those with no history of falls. Endurance – the capacity of the muscle to contract continuously at sub maximal levels also decreases with age. Endurance is better preserved with age than strength

Range of motion Decreased range of motion and loss of spinal flexibility in many older adults can lead to a characteristics flexed or stooped posture

ROM - continued Spinal flexibility shows the greatest decline with age, compared with all other joints and spinal extension shows the greatest decline, with 50% less spinal mobility in 70 – 84 year olds compared with young adults of 20 – 29 years old. Loss of spinal mobility can be associated with other changes in postural alignment, including a compensatory shift in the vertical displacement of center of body mass backward toward the heels. Arthritis and other conditions can lead to decrease ROM in many joints throughout the body. Pain may limit functional ROM

Neuromuscular system The NMS contributes to postural control through the coordination of forces effective in controlling the body’s position in space.

Changes in quiet stance Spontaneous swing during quiet stance Postural sway increases with each decade of life Greatest increase in postural sway in older adults with a history of falls. Velocity of sway greater in older adults with a history of falls. Small decline in balance function in the older adult.

Certain neurological disorders such as Parkinsons disease may have a normal or even a reduced swing in quiet stance due to increased stiffness and rigidity and this limits swing to smaller area during quiet stance.

Changes in motor strategies during perturbed stance Is the older adult capable of activating muscle response synergies with appropriate timing, force and muscle response organisation when balance is threatened? A study be Woolacott (1986) found that the motor strategies in younger adult and older adults were similar (ankle muscle and radiating to the muscles of the thigh). The older adult group tended to co activate the antagonist muscles along with the agonist muscles at a given joint significantly more often than younger adults. Thus many of the elderly studied tended to stiffen the joints to a greater degree than younger adults when compensating for sway perturbations

Changes in motor strategies during perturbed stance Several labs have found that many older adults used a strategy involving hip movements rather than ankle movements significantly more often than young adults (ankle muscle weakness? Loss of peripheral sensory function?) This may increase falls, particularly those associated with slipping.

Changes in motor strategies during perturbed stance In summary, both stable and unstable older adults show changes in the motor systems affecting postural control and that these can contribute significantly to an inability to maintain balance. Some of these changes include - Muscle weakness - Impaired timing and organisation among synergistic muscles activated in response to instability - Limitations in the ability to adapt movements for balance in response to changing task and environment demands.

Anticipatory postural abilities Postural adjustments are often used in a proactive manner, to stabilize the body before making a voluntary movement. Many studies suggest that many older adults haave problems making anticipatory postural adjustments quickly and effectively, especially without prior practice. This inability to stabilise the body in association with voluntary movement tasks such as lifting or carrying may be a major contributor to falls in many elderly.

Cognitive issues and postural control The effect of fear of falling on the control of balance There is now experimental evidence that anxiety and fear of falling affect the performance of older adults on tests of balance control.