Prof. Dr. Kemal Arıkan

Altered Functional Connectivity of the Alpha Rhythm, a State of Relaxation in Obsessive-Compulsive Disorder

Obsesif Kompulsif Bozuklukta İstirahat Hali Alfa Ritminin Fonksiyonel Bağlantı Değişiklikleri

Obsessive-Compulsive Disorder (OCD) is a common psychiatric disorder, in which recurrent thoughts and behaviors are observed that cause a specific anxiety in the person who has obsessions, compulsions or both.

Obsessive-Compulsive disorder has a prevalence rate of 2% to 3%, and it is more prevalent in men. Cognitive dysfunctions (executive dysfunction, in particular) were observed in OCD patients, on whom different research methods were used.

Many studies have shown that obsessive-compulsive disorder patients have structural and functional abnormalities in frontal lobe, hippocampus and caudate nucleus. These regions play a role in a number of impaired cognitive functions, including attention, memory, abstract thinking, processing of words, recognition of visual graphs, and spatial memory, which are observed in OCD patients.

Even though previous studies set forth that OCD patients had focal functional and structural abnormalities in specific brain regions, the pathogenesis and underlying mechanisms of OCD are still substantially unknown.

The eyes-open and eyes-closed electroencephalography (EEG) data were collected from healthy controls (HC) and OCD patients when they were in the state of relaxation, in order to investigate whether there were any changes in the functional brain connections (FBC) of obsessive-compulsive disorder patients.

Abnormal graph-theoretical parameters and impaired “small-world” traits were observed on the alpha and beta bands of OCD patients. Furthermore, it also showed that the long-amplitude alpha rhythm in the bilateral posterior regions, along with the FBC, decreased significantly in OCD patients compared to healthy controls, and that the FBC in the beta rhythm increased substantially in the eyes-open status. Consequently, it showed that the FBC in OCD patients could provide a new perspective for the diagnosis and treatment of OCD, and that abnormal “small-world” traits and a varying topological structure were shown particularly on the alpha and beta bands during relaxation.

* Small-World: A mathematical graph demonstrating the topological traits in brain connections.


  • DSM-V, Amerika Psikiyatri Birliği, Ruhsal Bozuklukların Tanısal ve Sayımsal Elkitabı,5. Baskı, Tanı Ölçütleri Başvuru Elkitabı, Çev. Köroğlu E, Hekimler Yayın Birliği,Ankara, 2014.
  • Tan, B., Liu, Q., Wan, C., Jin, Z., Yang, Y., & Li, L. (2018). Altered Functional Connectivity of Alpha Rhythm in Obsessive-Compulsive Disorder During Rest. Clinical EEG and Neuroscience, 155005941880437.

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