Compassion - Bridging Practice and Science - page 234

hormone (FSH)
and
luteinizing hormone (LH)
, which together drive the human sex organs and thereby control
sexual development, egg and sperm production and the menstrual cycle.
There is one vast hormonal system that deserves additional comment here and that is the
hypothalamic-
pituitary-adrenal (HPA) axis
, so named because it passes from the hypothalamus, through the anterior
pituitary and from there down to the
adrenal glands
in the abdomen. Along with the
autonomic nervous
system
, the HPA axis is the body’s primary stress response system, and its end product, the glucocorticoid
called
cortisol
, is arguably the body’s primary stress-related molecule (
). We say arguably, because
cortisol is charged with the strange role of feeding back on the HPA axis to turn itself off, which thereby makes
it probably the body’s most important anti-stress molecule. Cortisol is also well known to critically regulate
immune function. Cortisol has myriad physiological effects on brain and body that are beyond the scope of this
chapter, but as we shall see it appears to play important roles in compassion and related states such as
empathy, perhaps especially in the context of stress, which is known to strain people’s ability to maintain
compassionate attitudes.
With this brief survey of the endocrine system we turn now to examining associations between
compassion/empathy and oxytocin and cortisol. For the sake of consistency with other chapters in this volume,
we define empathy as sharing the emotional state of another, in contrast to compassion, which we take as the
aspiration to help free others from suffering. Following this we’ll extend our discussion to explore how effects
on these hormonal systems, as well as the autonomic nervous system, may help explain recent findings that
compassion may benefit immune functioning.
Associations of Oxytocin with Compassion and Related Emotional, Cognitive and Behavioral States
In the last ten years oxytocin has gone from the backwaters of labor and delivery to the front pages of the
scientific and popular press, all because of its growing reputation as the “love hormone”. As we’ll see, this
characterization is a partial truth at best, but not without some merit. The story of oxytocin and social
functioning began in many ways with a series of studies showing that oxytocin functioning in the brain
explained the remarkably different patterns of social behavior seen in two closely related subspecies of a
rodent called a vole[5]. Prairie voles form lifelong monogamous bonds between breeding partners and have
high levels of oxytocin receptors in key brain areas, especially the nucleus accumbens, a region repeatedly
associated with reward, reinforcement and motivation. On the other hand, montane voles are generally
promiscuous loners, and when one looks in their brains one sees far lower oxytocin activity. Moreover, studies
have shown that loyal, loving prairie voles can be made to behave like their more callous montane cousins by
disrupting oxytocin activity in their brains.
Increasing evidence suggests that in humans oxytocin plays a similarly important role in social processes in
general, and in prosocial emotions in particular. For example, several studies have shown that genetic
differences in the gene that encodes for the oxytocin receptor are associated with prosocial behavior and
empathy[6], [7], [8], as well as with neurological/psychiatric conditions such as autism that are characterized
by deficits or abnormalities in social behavior and empathy. Interestingly, these same genetic variants appear
to impact the structure and functional coupling of brain areas, including the hippocampus and amygdala, that
are essential for coping with stress and danger, especially when these threats are of a social nature[6].
If oxytocin is so important in trust, attachment and cognitive/emotional states of importance to compassion,
one might expect to find studies showing that increased levels of oxytocin are reliably associated with
increased compassion. In fact, the data on oxytocin levels and states related to compassion are very mixed,
and for a number of years this slowed research in the field. We suspect the lack of incontrovertible
associations between levels of oxytocin and empathy/compassion has to do with the fact that it is not so easy
to measure oxytocin where it matters. Unlike the situation in experimental animals, it is not possible to directly
measure oxytocin in the brains of living humans. It can be measured in spinal fluid but this requires a spinal
tap and measuring things in spinal fluid is a little bit like attempting to understand the functioning of a city by
studying its sewage discharge – not totally impossible, but far from ideal. Many studies have examined
oxytocin levels in the blood, but the issue with these studies is that it is far from clear how blood oxytocin
relates to oxytocin activity in the brain[9]. Nonetheless, some evidence suggests that empathy can affect
blood levels of oxytocin. For example, one study found that watching film clips designed to induce empathic
feelings for others found that self-reported increases in warmth, compassion (but not distress) predicted
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