Mind over matter
The June International Psychogeriatrics Article of the Month is entitled ‘Mind over matter – what do we know about neuroplasticity in adults?’ by Vyara Valkanova, Rocio Eguia Rodriguez and Klaus P. Ebmeier
Until recently the capacity of the human brain for structural and functional reorganization (brain plasticity) was considered to be limited to critical periods during development. Neuroimaging provides a non-invasive window into the living brain and has been used to study different aspects of brain plasticity during the learning of new skills or after novel experiences. We reviewed the strongest neuroimaging evidence for experience-dependent plasticity in adult humans, and therefore focused on longitudinal studies only (i.e. participants are scanned before and after different interventions, and then the images are compared).
We identified 36 studies that employed different types of training, such as juggling, exercising working memory, meditation, learning abstract information (studying for exams), and aerobic exercise. Although different patterns of results were found, there was consistent evidence that the brain (gray as well as white matter – brain cells as well as neuronal connections) retains much greater plasticity in adults (<75 years old) than is traditionally thought.
Before such research results can be translated into medical practice, there are many questions that still need to be answered. We currently do not know enough about the type and duration of the interventions that are effective, about the upper limits of improvement, how gains can be maintained, and most importantly the exact relationship between structural change and functional improvement. Further, all reviewed studies are in healthy individuals, while the impact of such interventions in patients with dementia is less well studied.
Future research will need to include larger samples and standardised training protocols to allow comparison of studies done at different research centres. Animal studies combining imaging with histological studies [detailed microscopic analysis] can be very useful in understanding the cellular mechanisms underlying learning, which is important when devising effective interventions. Finally, a multimodal imaging approach, where measures derived from complementary imaging modalities is likely to play a major role in increasing our understanding of brain plasticity. It is possible today, for example, to examine the volume of brain grey matter, the quality of anatomical connections between different areas of the brain and the degree of cooperation between different regions of the brain during the same examination, in other words to examine structural and functional brain connectivity. We know now that even the adult brain has a significant potential to change and compensate for any damage, for example after a stroke. Research in this area will have important implications for our ability to harness the natural self-healing and compensation properties of our brains to the greatest effect, in neurodegenerative diseases such as the dementias.