Kronik Psikiyatrik Hastalıklarda Nöroanatomi
Özet
Gelişen nörogörüntüleme teknolojileri, kronik psikiyatrik hastalıkların işlevsel bozukluklar olmanın ötesinde, belirgin yapısal ve fonksiyonel nöroanatomik değişikliklerle ilişkili olduğunu ortaya koymuştur. Şizofrenide en tutarlı bulgu, aşırı sinaptik budamaya bağlı yaygın beyin hacmi azalması, lateral ve üçüncü ventriküllerde genişleme ile nöral ağlar arasındaki bağlantıların zayıflamasıdır; ayrıca talamus, limbik sistem ve prefrontal kortekste de anormallikler saptanmıştır. Depresif bozuklukta periventriküler ve subkortikal alanlarda hiperintensite artışı, kortikal atrofi, prefrontal metabolizma ile serebral kan akışında azalma ve bellek sorunlarıyla ilişkili hipokampal hacim daralması ön plandadır. Anksiyete bozukluklarında çelişkili sonuçlar bulunsa da, en belirgin ortak bulgu anksiyete uyandıran durumlarda korku devresinin merkezi olan amigdala aktivitesindeki artıştır; panik bozuklukta temporal lob atrofisi ve sosyal anksiyete ile yaygın anksiyete bozukluklarında ilgili limbik/paralimbik bölgelerde hiperaktivite gözlenir. Obsesif kompülsif bozuklukta ise anterior singulat korteks hiperaktivitesi belirgin olup, orbitofrontal korteks, talamus ve kaudat çekirdeği arasındaki ağda işlevsel bozulmalar ve kaudat hacminde iki taraflı azalma saptanmıştır. Tüm bu kronik hastalıklarda saptanan nöroanatomik ve metabolik patolojilerin bir kısmı ilaç tedavileri ve davranışsal terapilerle düzelme gösterebilmektedir.
Advances in neuroimaging technologies have revealed that chronic psychiatric disorders extend beyond functional impairments and are associated with distinct structural and functional neuroanatomical changes. In schizophrenia, the most consistent findings are widespread brain volume reduction due to excessive synaptic pruning, enlargement of the lateral and third ventricles, and weakened connectivity among neural networks, alongside abnormalities in the thalamus, limbic system, and prefrontal cortex. Depressive disorder is primarily characterized by increased hyperintensity in periventricular and subcortical regions, cortical atrophy, decreased prefrontal metabolism and cerebral blood flow, and hippocampal volume reduction linked to memory deficits. Although neuroimaging yields conflicting results in anxiety disorders, the most prominent shared finding is heightened amygdala activity during anxiety-inducing situations, as it is central to the fear circuit; panic disorder exhibits temporal lobe atrophy, while social and generalized anxiety disorders show hyperactivity in relevant limbic and paralimbic structures. In obsessive-compulsive disorder, anterior cingulate cortex hyperactivity stands out, with functional disruptions in the network connecting the orbitofrontal cortex, thalamus, and caudate, as well as a bilateral reduction in caudate volume. A portion of these neuroanatomical and metabolic pathologies identified across these chronic conditions can exhibit improvement through pharmacological treatments and behavioral therapies.
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