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With all the recent postings on the subject of STRESS, I couldn't resist throwing my two cents in on this interesting and widely perceived factor. I believe there is a dynamic interaction between adrenalin (epinephrine) and dopamine. I think of stress as any condition which results in a tipping of the scale towards the adrenaline side of the equation. Consider the following: Akinesia and dyskinesia are generally considered to be pathology. However, I would suggest that they are not inherently pathologic but rather are normal components of motor function. It is the degree, duration and timing of these signs which are abnormal reflecting an imbalance in the levels or actions of neurotransmitters in PD. My point is that akinesia and dyskinesia are normally occurring stages of the progression from cue to motor response. One can get a sense of this by taking a close look at the components of the ANS fight/flight response. (i don't know how to enter diagrams, so here is a descriptive one); 1. environmental stimulus results in transient akinesia (epior norepi.mediated) 2. transient akinesia results in transient dyskinesia (dopaamine mediated) 3. transient dyskinesia results in appropriate response to stimuli (cognitive input) "Transient akinesia" is perceived as that momentary paralysis that occurs just after the adrenalin surge we feel when something startles us. "Transient dyskinesia" is perceived as that burst of energy that immediately follows. In order to convert this energy into some kind of rational behavior one must superimpose some cognitive control. However, one can get "stuck" in either transition stage. Primates who exhibit the "frozen in fear" phenomenon are in the "transient akinesia" stage because the intensity of the stimulus results in a degree of norepinephrine surge that in some way temporarily overwhelms the dopamine response. A situation where one gets stuck in the "transient dyskinesia stage would be a "panic attack", when the "appropriate response" does not remove the stimulus. Hysteria is a similar example when the stimulus persists because it is imagined and thus also unresponsive to the "appropriate response". When the stimulus originates internally there again is no way to generate an appropriate (cognitive) response, still the two transient stages which are neurophysiologic reactions still occur - this is what occurs during a seizure. This loop is part of the ANS fight or flight response. It's evolution's way of providing us with a very rapid response to a life threatening situation. What distinguishes it from the ordinary motor generating system is that in the former, initially there is a pronounced imbalance between the norepinephrine generated effects and the dopamine response. In the latter these two neurotransmitters are (in the absence of pathology) in equilibrium. These transient stages, in the ordinary motor generating system are too subtle to be noticed or perhaps don't even occur in when these two neurotransmitters are in equilibrium. However, in the fight or flight system, the exaggerated norepinephrine response magnifies the intensity of the transient stages making them briefly apparent. These stages also become apparent when they lose their transient quality, which is what occurs in PD. Akinesia occurs when there is inadequate supply of dopamine or sudden excess effect of adrenalin. The latter could account for how PD people can suddenly freeze while medicated in performance anxiety situations - trying to get to a ringing phone for example. The norepinephrine step is still present and as a result the stress-factor signs present. Notice how such a conceptual model can account for the often reported benefits of strenuous excercise which results in a subsequent shift away from the adrenalin side of the equation. Thus, one would predict the following effects of strenuous excercise: if meds were unchanged; increase dyskinesia longer periods of on time, or longer intervals between meds The automotive analogy Flight/fight.. akinesia resulting from epi surge = engine running, brake on, rpm's revved up dyskinesia = brake released car lurches ahead appropriate motor response (cognitive input) = steering ordinary motor response; as above but only a moderately elevated rpm's prior to release of brake which results in smooth steady acceleration. Tom Riess [log in to unmask]