What makes output energy less than input energy?

part of input energy is wasted

it is used to increase the entropy of the surrounding

therefore the useful energy output is necessarily smaller than the energy input

in other words the efficiency of heat engine is always less than hundred percent

dopamine..

"it was found that some people who were taking the drug l-dopa to raise their levels of dopamine were developing schizophrenic-like symptoms supporting research a strength of the dopamine hypothesis is that there are many studies which have shown support for the neurochemical explanation."