Changes of laboratory markers of cognitive brain function by thermostimuli in the elderly

Plain external applications of physical stimuli, which are used quite commonly in geriatric care in Germany, have not been studied for their influence on cognitive brain function. The aim of this randomized crossover study was to examine the influence of dermatoreceptive stimuli on cognitive brain function in healthy geriatric volunteers.

Twenty-four healthy volunteers (23 women, 1 man) were randomized into two groups (crossover design). Group A (mean age, 68.8+/-6.2 [SD] years) was treated with a 10 degrees C to 12 degrees C cold stimulus for 10 seconds (a so-called "Kneipp face shower"), followed by a cold 10 degrees C to 12 degrees C wetpack at the neck for 1 minute. Group B (mean age, 69.8+/-5.3 [SD] years) was subjected to an identical procedure but with warm to neutral temperatures of 34 degrees C to 36 degrees C. After I week the two groups were interchanged. The parameters of interest were the critical flicker frequency (CFF) and the latencies of the event-related P-300 potentials of the visual evoked potentials (VEP), which can be considered an electroencephalographic marker of the cognitive functional ability. The CFFs and the P-300 latencies and amplitudes were measured directly both before and 10 minutes after the application of the respective stimuli. In addition, the CFFs were recorded 30 and 60 minutes later.

After cold water stimuli were applied, the CFF increased from 32.55+/-2.26/sec (mean+/-SD) to 33.06+/-2.25/sec (p = .003) 10 minutes after the stimulus. Thirty minutes later the CFF was still elevated at 32.95+/-2.3/sec (p = .043). The P-300 latencies, after cold water application, decreased by 4.8% (p < .001), from 266.5+/-21.1msec (mean+/-SD) to 253.7+/-16.9msec. After warm stimuli they increased from 258.69+/-14.8msec to 266.17+/-20.1msec (p = .01). The P-300 amplitudes were significantly elevated, by 5% (p = .004), only after cold stimuli.

Cold water applied locally to the face and neck region can provoke significant changes in electroencephalographic markers as measured by an electroencephalographic marker (VEP and P-300 latency) and, by inference, may help to improve cognitive function in the elderly.