This question gets at the remarkable fact under our noses all day long: our ineffable thoughts and feelings are making concrete, physical, lasting changes in the structure and function of our brains. Neurons that fire together, wire together. This is learning, including the emotional, motivational, attitudinal and skills learning that is our focus in therapy. In other words, the making of memory – especially implicit memory, the storehouse of emotional residues of lived experience, knowing “how to,” expectations, assumptions, models of relationship, etc. distinct from explicit memory, the much smaller storehouse of specific recollections and knowing “about” – the gradual change of the structure and function of the brain.

In this context, any kind of mental change is evidence of neural change. Since neuroscience is a baby science, our current, noninvasive, imaging technologies have limited capacities to measure neural change in human beings – especially given how physically fine, fast, and complex these changes are. You could put five of the cell bodies of a typical neuron side by side in the width of just one of your hairs, and five thousand of the synapses, the connections, between neurons in the width of just one hair.

Nonetheless, even though the ethics of animal research trouble and even alarm many, including me, it is the case that more invasive research on animal learning – including emotional, motivational learning, that has some parallels to therapy – has established many fine-grained details of the ways in which experiences of stress, frustration, and trauma, as well as experiences of caring, success, and safety change the nervous system.

So we presume that neural change must be occurring if there is mental change. In this light, there are now many studies with human beings that show structural and functional changes after interventions such as training in mindfulness, compassion, body awareness, and psychotherapy. The cortex – the outer shell or “skin” of the brain – gets measurably thicker due to new synapses and greater infusion by capillaries for blood flow; key regions are more readily activated; there is also greater connectivity between regions, so they are more integrated and work better together; there are even changes in the expression of genes – tiny strips of atoms in the twisted up molecules of DNA in the nuclei of neurons.

And as your mind changes your brain for the better, these changes in your brain feed back to change your mind for the better as well. As these positive structural and functional changes in the brain occur, people become more capable and happy. For instance, training in mindfulness increases activation in the left prefrontal cortex, which supports a more positive mood.

As to new cell growth, I assume this is a reference to neurogenesis, the birth of new baby neurons, primarily in the hippocampus. We can encourage the birth of these neurons through exercise, and encourage their survival and wiring into memory networks through engaging in complexity and stimulation.

Here’s the takeaway: we can be confident in our own lives, and in our work with clients, that our efforts are bearing fruit in actual, physical changes in the nervous system. And since motivation is one of the primary factors shaping outcome in psychotherapy – and in life as a whole – this is heartening, wonderful news.

Most neuroplasticity is subtle and local, and does not change the overall architecture of the brain. I also think it is possible that there are individual variations in organic capacity for changing the brain, though I haven’t seen any studies on that (though they may exist).

I think a good starting point is to consider the vast diversity of human cultures, and the many individual examples of vast psychological changes – for better or worse – over the course of one person’s life. These illustrations of great mental plasticity are evidence for great neural plasticity in high impact ways, even if the vast majority of the synapses and circuits of the brain are unchanged.

The takeaway for me from this line of thinking is to appreciate the importance of hard work, of making little efforts each day that add up over time, to change your brain and thus your life for the better. And there’s a takeaway in terms of never betting against human potential and the human heart. Most of us have no idea how much we could grow psychologically or spiritually if we really gave ourselves to it, and put at least as much effort into it as we put into our occupation – or even our golf game!

As a broad principle, the brain regions or processes that are activated by an experience are the ones whose structure or function is most likely to be changed by the activation. 

Neuroscience is a baby science, with much that’s not known. There’s much that may be plausible that doesn’t yet have a specific study to back it up. 

This said, the conceptual, perspective aspects of the practice of reminding yourself mentally that everything is impermanent would tend to engage prefrontal areas that do conceptual processing, and with repetition and conviction, produce lasting changes there, i.e., learning, adopting, developing the habit of a new view. 

Also, the physical and emotional relaxation that would come with accepting transience would likely involve decreased sympathetic nervous system activity, increased parasympathetic nervous system activity, decreased stress hormones, and increased reward- and pleasure-related neurotransmitter activity (e.g., dopamine, natural opioids). With repetition, duration, and intensity of the experience, there would tend to be gradual changes in the resting state and responsiveness of these neural processes.

Last, evidence of mental change is evidence of neural change. Otherwise we are left with supernatural explanations. So if a person feels different or acts differently, something must have changed at the level of the body, particularly the brain.

There is tremendous evidence in published studies on psychological practices or interventions of various kinds – including the kinds I mention, notably relaxation and positive emotion practices – that they do lead to significant improvements in mental health indicators of various kinds: improvements that do change lives for the better in meaningful ways.

• There is also tons of evidence in research studies about the effects of frequency of spaced practice and the effects of personal effort. One implication is that for people who do not experience a benefit that changes their life in a meaningful-to-them way, are exceptions to that rule because they did not actually practice whatever it was (e.g., mindfulness, gratitude) a few times a day, day after day after day.
• Distinct from published research, I’ve received many anecdotal reports that my statement was true for them. This is evidence of a kind.
• I have personally experienced that my statement is true. An N of 1, for sure, but still definitely the evidence of my own experience.

As a personal detail, I worked for a year for a mathematician who did probabilistic risk analyses, and it was a fascinating consideration of levels of evidence for propositions about reality. As is increasingly noted in the scientific community, including the life sciences and social sciences, the dichotomous true/false distinction of “statistical significance/non-significance” is mathematically silly. The crux is how much uncertainty we have about propositions. Then the question becomes, to what extent do certain kinds of evidence reduce uncertainty. By the definition of information, relevant information of any kind reduces uncertainty. Information comes from many sources, most of which are not randomized control group double-blind studies. For example, roughly half of the methods used routinely in medical settings do not have a study behind them, but they are within the standard of care because there are other kinds of evidence for their legitimate use.