Magnetic resonance imaging in patients with obsessive-compulsive disorder with good versus poor insight
Aigner M, Zitterl W, Prayer D, Demal U, Bach M, et al.;
Commented by , 22 Nov 2005
Background
High incidences of structural as well as functional abnormalities found in recent brain imaging studies suggest that OCD is a neuropsychiatric disorder involving alterations in various brain structures and circuits, notably in the basal ganglia and the thalamo-cortical-basal ganglia loops.
Aims of the study
To investigate the relative frequency of structural brain abnormalities in two subtypes of obsessive-compulsive disorder, namely OCD "with good insight" and OCD "with poor insight".
Method
84 patients meeting DSM-IV as well as ICD-10 criteria for OCD underwent structural magnetic resonance imaging (MRI). Participants were subdivided (by two psychiatrists and one psychologist) in patients with insight and patients with poor insight as defined by DSM-IV. MRI examinations were performed by radiologists who were unaware of any subtype diagnoses.
Results
Most patients (83%) who had OCD with poor insight showed MRI abnormalities while such abnormalities were detected in only a minority of patients (21%) with good insight. The basal ganglia were the most often affected structure, followed by abnormalities in the parietal lobe, the occipital lobe and the frontal lobe, and abnormalities of the ventrical system. In a few cases, various other structures were also affected.
Professor Pull's comments
OCD has been investigated extensively in neuroimaging studies, including a large number of MRI studies. Most studies have found neuroanatomical abnormalities in a significant proportion of patients. Findings have not been consistent, however, across studies.
Inconsistencies in MRI findings can be the result of many factors. Among the factors to be considered are: variations in imaging techniques and analyses, sample size, comorbid disorders, age of onset, duration of illness, gender, and the diversity of OCD symptoms.
Inconsistencies in MRI findings could be the result, in particular, of phenotypic heterogeneity. Different subtypes have been proposed, including subtypes characterized by specified compulsions such as washing, checking, hoarding, that may be associated with different MRI findings.
Another way to subtype OCD has been included in DSM-IV, using the specifier "with poor insight". According to DSM-IV, the specifier "with poor insight" can be applied when, for most of the time during the current episode, the individual does not recognize that the obsessions or compulsions are excessive or unreasonable.
Results from recent studies suggest that poor insight may indeed identify a group of OCD patients with distinct clinical characteristics. In particular, the poor insight subtype of OCD has been linked to the Y-BOCS score for compulsions, to chronic course of the disorder, and to a family history of OCD (ref. 1), to poor response to drug treatment (ref. 2), and to high levels of alexithymia (ref. 3).
The results of the present study suggest that most cases of OCD with poor insight may be linked to a neuroanatomical abnormality, most notably a structural alteration of the basal ganglia. Although these findings need to be replicated, they give additional support to the concept of OCD with poor insight as a distinct subtype of the disorder.
References
1. Bellino S, Patria L, Ziero S and Bogetto F. Clinical picture of obsessive-compulsive disorder with poor insight: a regression model. Psychiatry Research 2005; 136 (2-3); 223-231
2. Ravi Kishore V, Samar R, Janardhan Reddy YC, Chandrasekhar CR and Thennarasu K. Clinical characteristics and treatment response in poor and good insight obsessive-compulsive disorder. European Psychiatry 2004; 19 (4); 202-208
3. De Berardis D, Campanella D, Gambi F, Sepede G, et al. Insight and alexithymia in adult outpatients with obsessive-compulsive disorder. European archives of psychiatry and clinical neuroscience 2005; 255 (5); 350-358