Classification of comorbidity in obsessive-compulsive disorder: A latent class analysis

OBJECTIVE

Patients with OCD differ markedly from one another in both number and kind of comorbid disorders. In this study, we set out to identify and characterize homogeneous subgroups of OCD patients based on their comorbidity profile.

METHODS

In a cohort of 419 adult subjects with OCD, the lifetime presence of fifteen comorbid disorders was assessed. Latent class analysis was used to identify comorbidity-based subgroups. Groups were compared with regard to core clinical characteristics: familiality, childhood trauma, age at onset, illness severity, OCD symptom dimensions, personality characteristics, and course of illness.

RESULTS

The study sample could be divided in a large group (n = 311) with a low amount of comorbidity that could be further subdivided into two subgroups: OCD simplex (n = 147) and OCD with lifetime major depressive disorder (n = 186), and a group (n = 108) with a high amount of comorbidity that could be further subdivided into a general anxiety-related subgroup (n = 49), an autism/social phobia-related subgroup (n = 27), and a psychosis/bipolar-related subgroup (n = 10). Membership of the high-comorbid subgroup was associated with higher scores on childhood trauma, illness severity, and the aggression/checking symptom dimension and lower scores on several personality characteristics.

CONCLUSION

Grouping OCD patients based on their comorbidity profile might provide more homogeneous, and therefore, more suitable categories for future studies aimed at unraveling the etiological mechanisms underlying this debilitating disorder.

Perceptions of free will in obsessive-compulsive disorder: a quantitative analysis

BACKGROUND

The aim of this study was to explore perceptions of free will in the repetitive behaviors of patients with obsessive-compulsive disorder (OCD) and to explore their relation with core clinical characteristics.

METHODS

Experiences of free will were assessed with the Symptomatology And Perceived Free will rating scale (SAPF) in 295 subjects with a lifetime diagnosis of OCD. Patients' scores on the SAPF were subjected to an explorative principal axis factor analysis (PAF). Factor scores were regressed on five OCD symptom dimensions and on seven clinical variables: illness duration, severity of OCD, insight, anxiety and depression, suicidal ideation and quality of life.

RESULTS

The PAF revealed three factors: the perceived ability to control and change one's course of action when faced with an obsession or compulsion (the "alternative possibilities" factor); the experience of obsessions or compulsions as intentional (the "intentionality" factor); and the experience of being the source or owner of the obsessions or compulsions (the "ownership" factor). Lower scores on the "alternative possibilities" factor were associated with lower scores on the washing dimension (β = 0.237, p = 0.004) and higher scores on the precision dimension (β = - 0.190, p = 0.025) and independently associated with longer illness duration (β = - 0.134, p = 0.039), higher illness severity (β = - 0.298, p < 0.001) and lower quality of life (β = 0.172, p = 0.046). Lower scores on the "intentionality" factor were independently associated with lower quality of life (β = 0.233, p = 0.027). Higher scores on the "ownership" factor were associated with higher scores on the precision dimension (β = 0.207, p = 0.023) and independently associated with poorer insight (β = 0.170, p = 0.045).

CONCLUSIONS

The most notable finding of this study is that a diminished experience of free will in OCD is associated with core clinical characteristics: illness duration and severity, insight and quality of life.

Chronic obsessive-compulsive disorder: prognostic factors

BACKGROUND

The course of illness in obsessive-compulsive disorder (OCD) varies significantly between patients. Little is known about factors predicting a chronic course of illness. The aim of this study is to identify factors involved in inducing and in maintaining chronicity in OCD.

METHODS

The present study is embedded within the Netherlands Obsessive Compulsive Disorder Association (NOCDA) study, an ongoing multicenter naturalistic cohort study designed to identify predictors of long-term course and outcome in OCD. For this study, 270 subjects with a current diagnosis of OCD were included. Chronicity status at 2-year follow-up was regressed on a selection of baseline predictors related to OCD, to comorbidity and to stress and support.

RESULTS

Psychotrauma [odds ratio (OR) 1.98, confidence interval (CI) 1.22-3.22, p = 0.006], recent negative life events (OR 1.42, CI 1.01-2.01, p = 0.043), and presence of a partner (OR 0.28, CI 0.09-0.85, p = 0.025) influenced the risk of becoming chronic. Longer illness duration (OR 1.46, CI 1.08-1.96, p = 0.013) and higher illness severity (OR 1.09, CI 1.03-1.16, p = 0.003) increased the risk of remaining chronic.

CONCLUSIONS

External influences increase the risk of becoming chronic, whereas the factors involved in maintaining chronicity are illness-related. As the latter are potentially difficult to modify, treatment should be devoted to prevent chronicity from occurring in the first place. Therapeutic strategies aimed at alleviating stress and at boosting social support might aid in achieving this goal.

Clinical predictors of seizure threshold in electroconvulsive therapy: a prospective study

At the start and during the course of electroconvulsive therapy (ECT), estimation of the seizure threshold (ST) is useful in weighing the expected effectiveness against the risks of side effects. Therefore, this study explores clinical factors predicting initial ST (IST) and levels of ST during the ECT course. This prospective observational study included patients aged ≥18 years receiving ECT without contraindications for dose titration. At the first and every sixth consecutive ECT session, ST level was measured. Using multivariate linear regression and multilevel models, predictors for IST and change in ST levels were examined. A total of 91 patients (mean age, 59.1 ± 15.0 years; 37 % male; 97 % diagnosis of depression) were included. In multivariable analysis, higher age (β = 0.24; P = 0.03) and bifrontotemporal (BL) electrode placement (β = 0.42; P < 0.001) were independent predictors for higher IST, explaining 49 % of its variation. Also, these two variables independently predicted higher ST levels at different time points during the course. Using multilevel models, absence of a previous ECT course(s) predicted a steeper rise in ST during the course (P = 0.03 for the interaction term time*previous ECT). The age-adjusted dose-titration method is somewhat crude, resulting in some measurement error. Concomitant medication use could have influenced ST levels. Increasing age and BL electrode placement predicted higher (I)ST, which should be taken into account when selecting ECT dosage. Previous ECT course(s) may avoid an increase in ST during the course of ECT.

Diffusion tensor imaging and cognition in cerebral small vessel disease: the RUN DMC study

BACKGROUND

Cerebral small vessel disease (SVD) is very common in elderly and related to cognition, although this relation is weak. This might be because the underlying pathology of white matter lesions (WML) is diverse and cannot be properly appreciated with conventional FLAIR MRI. In addition, conventional MRI is not sensitive to early loss of microstructural integrity of the normal appearing white matter (NAWM), which might be an important factor. Diffusion tensor imaging (DTI) provides alternative information on microstructural white matter integrity and we have used this to investigate the relation between white matter integrity, in both WML and NAWM, and cognition among elderly with cerebral SVD.

METHODS

The RUN DMC study is a prospective cohort study among 503 independently living, non-demented elderly with cerebral SVD aged between 50 and 85 years. All subjects underwent MRI and DTI scanning. WML were segmented manually. We measured mean diffusivity (MD) and fractional anisotropy (FA), as assessed by DTI in both WML and NAWM.

RESULTS

Inverse relations were found between MD in the WML and NAWM and global cognitive function (β=-.11, p<0.05; β=-.18, p<0.001), psychomotor speed (β=-.15, p<0.01; β=-.18, p<0.001), concept shifting (β=-.11, p<0.05; β=-.10, p<0.05) and attention (β=-.12, p<0.05; β=-.15, p<0.001). The relation between DTI parameters in both WML and NAWM and cognitive performance was most pronounced in subjects with severe WML.

CONCLUSION

DTI parameters in both WML and NAWM correlate with cognitive performance, independent of SVD. DTI may be a promising tool in exploring the mechanisms of cognitive decline and could function as a surrogate marker for disease progression in therapeutic trials. This article is part of a Special Issue entitled: Imaging Brain Aging and Neurodegenerative disease.

Hypertension and cerebral diffusion tensor imaging in small vessel disease

BACKGROUND AND PURPOSE

Hypertension is a risk factor for cerebral small vessel disease, which includes white matter lesions (WML) and lacunar infarcts. These lesions are frequently observed on MRI scans of elderly people and play a role in cognitive decline. Preferably, one would like to evaluate the effect of hypertension before fluid-attenuated inversion recovery visible macrostructural lesions occur, possibly by investigating its effect on the microstructural integrity of the white matter. Diffusion tensor imaging provides measures of structural integrity.

METHODS

In 503 patients with small vessel disease, aged between 50 and 85 years, we cross-sectionally studied the relation between blood pressure, hypertension, and hypertension treatment status and diffusion tensor imaging parameters in both normal-appearing white matter (NAWM) and WMLs. All of the subjects underwent 1.5-T MRI and diffusion tensor imaging scanning. Fractional anisotropy and mean diffusivity were calculated in both NAWM and WMLs.

RESULTS

Increased blood pressure and hypertension were significantly related to lower fractional anisotropy in both NAWM and WMLs and to higher mean diffusivity in WMLs. For hypertensives, odds ratios for the risk of impaired microstructural integrity (fractional anisotropy) were 3.1 (95% CI: 1.8 to 5.7) and 2.1 (95% CI: 1.2 to 3.5) in NAWM and WMLs, respectively, compared with normotensives. Fractional anisotropy odds ratios for treated uncontrolled subjects were 6.5 (95% CI: 3.3 to 12.7) and 2.7 (95% CI: 1.5 to 5.1) in NAWM and WMLs, respectively, compared with normotensives.

CONCLUSIONS

Our data show that diffusion tensor imaging may be an appropriate tool to monitor the effect of blood pressure and the response to treatment on white matter integrity, probably even before the development of WMLs on fluid-attenuated inversion recovery.

Gait in elderly with cerebral small vessel disease

BACKGROUND AND PURPOSE

Gait disorders are common in the elderly and are related to loss of functional independence and death. White matter lesions (WMLs) may be related, but only a minority of individuals with WMLs has gait disorders. Probably other factors are involved, including location and the independent effect of frequently coinciding lacunar infarcts, the other aspect of cerebral small vessel disease. The aim of our study was to investigate the effect of both the severity and location of both WMLs and lacunar infarcts on gait.

METHODS

Four hundred thirty-one independently living, nondemented elderly aged between 50 and 85 years with cerebral small vessel disease were included in this analysis and underwent MRI scanning. The number and location of lacunar infarcts were rated and WML volume was assessed by manual segmentation with automated delineating of different regions. Gait was assessed quantitatively with an electronic walkway as well as the semiquantitatively Tinetti and Timed-Up-and-Go test.

RESULTS

WMLs and lacunar infarcts were both independently associated with most gait parameters with stride length as the most sensitive parameter related to WMLs. WMLs in the sublobar (basal ganglia/internal capsule) and limbic areas and lacunar infarcts in the frontal lobe and thalamus were related to a lower velocity.

CONCLUSIONS

Cerebral small vessel disease is related to gait disturbances. Because small vessel disease may, in part, be preventable, it should be regarded as a potentially important target for postponing gait impairment.

Patterns of cortical degeneration in an elderly cohort with cerebral small vessel disease

Emerging noninvasive neuroimaging techniques allow for the morphometric analysis of patterns of gray and white matter degeneration in vivo, which may help explain and predict the occurrence of cognitive impairment and Alzheimer's disease. A single center prospective follow-up study (Radboud University Nijmegen Diffusion tensor and Magnetic resonance imaging Cohort study (RUN DMC)) was performed involving 503 nondemented elderly individuals (50-85 years) with a history of symptomatic cerebral small vessel disease (SVD). Age was associated with a global reduction in cortical thickness, and this relationship was strongest for ventrolateral prefrontal cortex, auditory cortex, Wernicke's area, superior temporal lobe, and primary visual cortex. Right and left hemispheres differed in the thickness of language-related areas. White matter (WM) lesions were generally negatively correlated with cortical thickness, primarily in individuals over the age of 60, with the notable exception of Brodmann areas 4 and 5, which were positively correlated in age groups 50-60 and 60-70, respectively. The observed pattern of age-related decline may explain problems in memory and executive functions, which are already well documented in individuals with SVD. The additional gray matter loss affecting visual and auditory cortex, and specifically the head region of primary motor cortex, may indicate morphological correlates of impaired sensory and motor functions. The paradoxical positive relationship between WM lesion volume and cortical thickness in some areas may reflect early compensatory hypertrophy. This study raises a further interest in the mechanisms underlying cerebral gray and white matter degeneration in association with SVD, which will require further investigation with diffusion weighted and longitudinal MR studies.