Timothy C. Hain, MD • Page last modified: August 29, 2020
Many individuals with vestibular disorders complain of trouble thinking. Most commonly people say that they can't "multitask". This difficult thinking is measurable and significant. Redfern and others documented that reaction times are longer in patients with unilateral vestibular loss than normal controls (2003). This effect increases when patients are attempting to balance. Similarly, persons whose blood pressure drops when they stand have more trouble thinking on their feet (to to speak). So this effect is not a specific one.
Normal subjects also exhibit longer reaction times when responding to postural perturbations. This appears to be due to a diversion of attention to postural demands, leaving less available for cognitive processing of other input (Redfern et al, 2002). Older adults are more vulnerable to this effect (Shumway-Cook and Wollacott, 2000; Smolders et al, 2010). Younger adults seem to degrade their cognition rather than balance (Berger and Bernadrd-Demanze, 2011).
Subjects with vestibular disorders find it more difficult to walk in a straight line than normal subjects, and "veering" increases with tasking. (Roberts et al, 2011). Cognitive performance also suffers (e.g. Nascimbeni et al, 2010). However, in general, postural tasks are preferred and performance does not suffer as much as cognitive tasks (Resch et al, 2011).
Subjects undergoing galvanic ear stimulation (electrical currents being pass through inner ear) suffer from degraded spatial processing (Dilda et al, 2011). (of course).
Subjects with bilateral vestibular loss (but not unilateral) are found to have more difficulty with mental spatial transformations (Grabheer et al, 2011).
According to Mignardot and others (2010), overweight persons have more difficulty with multitasking. Thus this research methology seems to suggest positive findings in somewhat unexpected places.
Practice, training, and compensation are all thought to make postural tasks more automatic (e.g. Kuczynski et al, 2011), demanding less thought.
Sometimes stimulants are helpful. Of course, stimulants may make anxiety worse, and may be addictive too, so their use should be judicious.
Sedatives that reduce one's ability to think, also reduce one's ability to balance.
Antidepressants all seem to reduce balance, presumably through a similar mechanism.