Reproductive Medicine, Chronobiology
and Human Ethology, ISSN 0172780X
Vol.25 No.4, Aug 2004
addiction and their health implications
Esch 1,3 & George B. Stefano 2,3
Charité University Medicine Berlin, Institute
for General Practice and Family Medicine, Berlin, Germany
2 Neuroscience Research Institute, State University of New
York College at Old Westbury, Old Westbury, New York, USA
3 Beijing Foreign Affairs University, Beijing Wellness Medical
Center, South Stone Torii Chang Ping, Beijing, China.
July 25, 2004 Accepted: July 27, 2004
pleasure; reward; addiction; motivation; placebo; dopamine;
science begins to understand pleasure as a potential component
of salutogenesis. Thereby, pleasure is described as a state
or feeling of happiness and satisfaction resulting from an
experience that one enjoys. We examine the neurobiological
factors underlying reward processes and pleasure phenomena.
Further, health implications related to pleasurable activities
are analyzed. With regard to possible negative effects of
pleasure, we focus on addiction and motivational toxicity.
Pleasure can serve cognition, productivity and health, but
simultaneously promotes addiction and other negative behaviors,
i.e., motivational toxicity. It is a complex neurobiological
phenomenon, relying on reward circuitry or limbic activity.
These processes involve dopaminergic signaling. Moreover,
endorphin and endogenous morphinergic mechanisms may play
a role. Natural rewarding activities are necessary for survival
and appetitive motivation, usually governing beneficial biological
behaviors like eating, sex and reproduction. Social contacts
can further facilitate the positive effects exerted by pleasurable
experiences. However, artificial stimulants can be detrimental,
since flexibility and normal control of behavior are deteriorated.
Additionally, addictive drugs are capable of directly acting
on reward pathways. Thus, the concrete outcome of pleasant
experiences may be a question of dose. Moderate pleasurable
experiences are able to enhance biological flexibility and
health. Hence, pleasure can be a resistance resource or may
serve salutogenesis. Natural rewards are mediated by sensory
organ stimulation, thereby exhibiting a potential association
with complementary medical approaches. Trust and belief can
be part of a self-healing potential connected with rewarding
stimuli. Further, the placebo response physiologically resembles
pleasure phenomena, since both involve brains reward
circuitry stimulation and subjective feelings of well-being.
Pleasurable activities can stimulate personal growth and may
help to induce healthy behavioral changes, including stress
management. However, more research is needed to better understand
the nature, neurobiology and maybe dangerous aspects of pleasure.
Also, a possible involvement of endogenous morphinergic signaling
has to be studied
is typically interested in disease-promoting factors and ways
to cure. However, health-enhancing factors are becoming more
popular, and the concept of salutogenesis and its association
with self-care is of growing importance [1,2]. This may be
due to money shortage in the health care system - in relation
to its demands - and the rapidly increasing interest in preventive
medicine and disease avoidance.
For neuroscientists, the brain most often is related to neural
disorders and disease mechanisms - which are of interest,
undoubtedly. But much could also be learned by studying the
brain in relation to health. The brain has processes and salutogenic
functions that contribute to health by enabling one's experiences
in life to benefit one's health (Figure 1) . Science has
ever neglected positive sensations and mind states like satisfaction
and contentment, solely focusing upon pathogenetic processes.
For example, a vast number of publications on depression and
mental disorders exist, but only a few describe possible mechanisms
underlying feelings of joy and bliss.
What makes one feel good instead of bad? What are possible
resources within the brain that medicine may want to use?
May pleasure possibly be a concept that is available for each
individual to protect from disease or serve health processes?
Besides feeling good, what are the biological implications
of pleasurable sensations, and what are the risks of pleasure-seeking
behavior, i.e., addiction? May pleasure, at last, facilitate
survival and early death likewise?
With this work we try to examine the neurobiology of pleasure
and shed some light on implicated risks, health consequences
and molecular mechanisms in connection with the pleasure phenomenon.
has identified a biological mechanism mediating behavior motivated
by events commonly associated with pleasure. This mechanism
is called 'reward'. It is usually governing normal behavior
through pleasurable experiences . Pleasure, however, describes
a 'state or feeling of happiness or satisfaction resulting
from an experience that one enjoys' . Pleasure is a subjective
phenomenon, i.e., subjective quality. Hence, an intimate association
between reward and pleasure exists [4,6]. In neurobiology,
pleasure is a competence or function of the reward and motivation
circuitries that are imbedded in the central nervous system
(CNS). Anatomically, these reward pathways are particularly
linked to the brain's limbic system. The underlying physiology,
however, is complex and morphological correlates are still
a matter of thorough research.
text of this Review article:
Motivation may be divided into two categories - appetitive
and aversive motivation. Appetitive motivation concerns behavior
directed towards goals that are normally associated with positive
hedonic, i.e., pleasurable, processes (food, recreational
drugs, sex etc.). In contrast, aversive motivation involves
getting away from hedonically unpleasant conditions . Consequently,
two fundamental forces rule motivation: pleasure and pain.
It has been suggested that pleasure may be associated with
beneception, events that facilitate survival and thus 'benefit'
the organism or species from an evolutionary biology perspective
. Pain, on the other hand, is associated with nociception.
This latter term basically describes conditions that may have
undesirable biological consequences for an organism [4,7].
However, the illustrated division of pleasure and pain in
reference to their possible biological functions and outcome
should not lead to an incorrect understanding, since both
conditions - in specific situations - may have the capacity
to serve survival and 'amusement' likewise. Thus, pain and
pleasure potentially merge into another. With regard to specialized
brain compartments involved in motivational processes, the
physiological substrate for appetitive or aversive motivation
(as for reward and avoidance) primarily lies within the limbic
The common idea that the limbic system is solely concerned
with feelings and emotion is at best a half-truth, but there
certainly exists a connection which is relevant to the pleasure
phenomenon . Yet, the limbic system is made up of the
limbic lobe and certain additional structures (Figure 2) .
The limbic lobe surrounds the corpus callosum and consists
of the cingulate gyrus and the parahippocampal gyrus. The
hippocampus, which is in the floor of the temporal horn of
the lateral ventricle and is closely linked to memory processing,
is also included in the limbic lobe . Additional structures
incorporated in the limbic system are the dentate gyrus, amygdala,
hypothalamus (especially the mammillary bodies), septal area
(in the basal forebrain) and thalamus (anterior and some other
nuclei). Functionally, the 'hippocampal formation' consists
of the hippocampus, the dentate gyrus and most of the parahippocampal
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