Knowledge about possible structural abnormalities present in the brain of those suffering from OCD improve. It is a disorder characterized by symptoms such as recurrent and persistent ideas and impulses recognized as meaningless by the individual himself (obsessions) and by repetitive behaviors often implemented precisely in response to obsessions, or with the aim of preventing and neutralizing feared events or situations (compulsioni). A study carried out by a large group of international researchers, published in the journal Translational Psychiatry indicates that some posterior brain areas could also be involved in the genesis of this disorder, thus extending the network of involved areas, hitherto considered above all the anterior ones, such as the frontal lobes, and deep gray matter nuclei, such as the striated nucleus.
Very extensive alterations
The results of our study extend the knowledge related to the localization of brain abnormalities in OCD – they say Fabrizio Piras and Federica Piras, neuropsychologists and researchers of the Santa Lucia IRCCS in Rome, e Gianfranco Spalletta, psychiatrist and director of the neuropsychiatry laboratory of the Santa Lucia IRCCS in Rome -. Over the last few decades, it has been established that at the base of the disorder there is an alteration of the fronto-striatal circuit – frontal lobes and striatum. Subsequently, the neuroanatomical model was integrated with the brain areas involved in the processing of emotions, such as the cortex of the girdle, the amygdala and the hippocampus. The results of our study now indicate the involvement of posterior brain areas as well and seem to confirm that the disorder is due to much more extensive alterations than previously believed. But what exactly are the alterations that the brain areas undergo in this disorder? Several experimental evidences suggest the existence of abnormalities in white matter myelination.
The myelination process
Myelination is a maturation process of the nerve fibers which makes them progressively more isolated and thus allows a faster and more efficient transmission of information, hence better functionality. Alterations in myelination are now considered potentially responsible for various psychic disorders. The researchers further explain: The observation that some compulsive traits are related to the myelination process even in the normal population suggests that the compulsive implementation of certain behaviors or mental processes can alter the normal processes of myelination over time, with reduced growth of the myelin sheath since adolescence. Then these effects would continue into adulthood. The repetitiveness of mental behaviors and activities, typical of obsessive compulsive disorder, would not allow the realization of those normal cerebral structural changes that are a consequence of the interaction with the environment, thus interfering with the process of maturation of nerve fibers, driven by experience. The scarcity of factors that stimulate the myelination process, such as exposure to external stimuli that promote white matter organization and reorganization, could also account for the alterations observed in adult patients with OCD. An impoverished environment, in fact, both the cause and the consequence of obsessive-compulsive disorder.
The role of drugs
There also appears to be a relationship between the integrity of some traits of the myelin sheath and the intake of drugs used to control obsessive-compulsive symptoms. White matter alteration may also be related in some way to pharmacotherapy. In fact, some of the drugs used to treat this ailment, such as serotonin reuptake inhibitors and certain antipsychotics could, over time, affect the proliferation of cells responsible for the myelination process. The functioning of these drugs is in fact based on the reduction of the efficiency and speed of transmission within the cerebral circuit responsible for the disorder, generally characterized by hyperactivity. The study was carried out using Diffusion Tensor Imaging (DTI), a technique that uses the principles of magnetic resonance to quantify the movement of water molecules within brain tissue. Through the analysis of some indices derived from this method it is possible to highlight microstructural alterations in the bundles of fibers that connect the various brain areas. Our study demonstrates the presence of these alterations only in the adult population, alterations that can be considered a signal of disease, since they are related to some clinical variables, such as age of onset and duration of disease, even if they do not seem correlate with the severity of symptoms. Interesting to note that we did not find any significant results in the pediatric population and this suggests that microstructural alterations may occur later in the progression of the disease.
Resort to psychotherapy
This research not only offers a better understanding of the neurobiological mechanisms of OCD, but also opens up potential indications for possible treatments. Given that the eventual alteration of the myelination process seems to take place during adolescence, in correspondence with a moment of intense brain development, interventions aimed at promoting the maturation process of the white matter could be usefully implemented in this phase of growth – Piras and Spalletta conclude -. In particular, an environment rich in cognitive and social stimuli could be useful in positively orienting the processes of brain reorganization which generally take place during adolescence. Regarding adulthood, given the possible long-term adverse effect of pharmacotherapy on the myelination process, it would be useful to consider as often as possible the use of psychotherapeutic techniques, especially cognitive-behavioral, opting for drugs only in the event of a possible failure of psychotherapy. Since even the adult brain shows a certain degree of plasticity, any interventions of stimulation and cognitive neurorehabilitation could be useful even after adolescence.
April 19, 2021 (change April 19, 2021 | 21:41)
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