Co-morbid obsessive-compulsive disorder and depression: a Bayesian network approach

BACKGROUND

Obsessive-compulsive disorder (OCD) is often co-morbid with depression. Using the methods of network analysis, we computed two networks that disclose the potentially causal relationships among symptoms of these two disorders in 408 adult patients with primary OCD and co-morbid depression symptoms.

METHOD

We examined the relationship between the symptoms constituting these syndromes by computing a (regularized) partial correlation network via the graphical LASSO procedure, and a directed acyclic graph (DAG) via a Bayesian hill-climbing algorithm.

RESULTS

The results suggest that the degree of interference and distress associated with obsessions, and the degree of interference associated with compulsions, are the chief drivers of co-morbidity. Moreover, activation of the depression cluster appears to occur solely through distress associated with obsessions activating sadness - a key symptom that 'bridges' the two syndromic clusters in the DAG.

CONCLUSIONS

Bayesian analysis can expand the repertoire of network analytic approaches to psychopathology. We discuss clinical implications and limitations of our findings.

Suppression of the emotional Stroop effect by increased anxiety in patients with social phobia

Anxious individuals are slower at color-naming threat-related than nonthreat-related words in the emotional Stroop task. Recently, Mathews and Sebastian (1993, Cognition and Emotion, 7, 527-530) reported that this Stroop interference effect disappears when snake-fearful students are exposed to a snake while performing the color-naming task. In the present experiment, we had patients with social phobia and normal control subjects perform an emotional Stroop task under either low anxiety (i.e. upon entering the laboratory) or high anxiety (i.e. before giving a speech). Results indicated that Stroop interference for socially threatening words in the phobic group was suppressed under high anxiety. These findings may indicate that increased effort enables the subjects to suppress the interference produced in the Stroop task.

Implicit memory bias for threat in panic disorder: application of the 'white noise' paradigm

We employed Jacoby's white noise paradigm to investigate implicit memory bias for threat in panic disorder and in normal control subjects. Subjects heard a series of neutral sentences (e.g. "The shiny apple sat on the table") and panic sentences (e.g. "The anxious woman panicked in the supermarket"). Implicit memory for this prior exposure was then tested by having subjects rate the volume of white noise accompanying the presentation of 'old' sentences intermixed with 'new' sentences. Implicit memory for old sentences is revealed when subjects rate the white noise accompanying these sentences as less loud than noise accompanying new sentences. Results revealed that under low noise level, panic patients demonstrated an implicit memory bias for threat information, whereas control subjects did not. This differential priming effect suggests that information about threat may be automatically accessed in these patients.

Cognitive processing of idiographic emotional information in panic disorder

Panic disorder patients, obsessive-compulsive disorder (OCD) patients, and normal control subjects performed a computerized Stroop color-naming task in which they named the colors of panic-threat words (e.g. Collapse), general-threat words (e.g. Infectious), positive words related to panic (e.g. Relaxed), and neutral words (e.g. Sleepy). Idiographic stimulus selection ensured their personal emotional relevance for each subject. In accordance with prediction, panic patients, but not OCD patients, exhibited greater interference for panic-threat words than for positive words related to panic and for neutral words. Panic patients did not respond differentially to panic-threat and general-threat words. Complexities concerning attentional bias research in the anxiety disorders are discussed.

Anorexia nervosa in an elderly man

Anorexia nervosa (AN) rarely develops after the age of 30 years, and rarely occurs in men. We report a case of chronic AN in a 72-year-old man, who reported a 20-year history of extreme low body weight, persistent fears of obesity, and feelings of being fat even at 93 lb. Also reported were episodes of self-induced vomiting, laxative abuse, and excessive exercising. Patient's scores on a battery of questionnaires were also consistent with a diagnosis of AN.

Cognitive processing of emotional information in panic disorder

Panic-disordered (PD) patients, obsessive-compulsive (OCD) patients, and normal control subjects were exposed to either a high (i.e. exercise) or low arousal manipulation prior to performing a computerized version of the modified Stroop color-naming paradigm. Subjects named the colors of neutral nonlexical stimuli, positive words, and threat words associated with fear, bodily sensations, and catastrophes. After the Stroop task, subjects rated the personal emotional significance of the words. Inconsistent with the emotionality hypothesis of Stroop interference, PD patients rated positive words as more emotional than catastrophe words, but took longer to color-name the latter than the former. Yet consistent with the emotionality hypothesis, PD patients took as long to color-name positive words as to color-name fear and bodily sensation words. Contrary to expectation, OCD patients resembled PD patients in terms of interference, and arousal did not enhance interference for threat words in PD patients.

Selective processing of threat cues in posttraumatic stress disorder

Vietnam combat veterans with (n = 15) and without (n = 15) posttraumatic stress disorder (PTSD) performed a modified Stroop task in which they named the colors of neutral words (e.g., INPUT), positive words (e.g., LOVE), obsessive-compulsive disorder (OCD) words (e.g., GERMS), and PTSD words (e.g., BODYBAGS). In contrast to normal controls, PTSD patients took significantly longer to color-name PTSD words than to color-name neutral, OCD, and positive words. Because Stroop interference reflects involuntary semantic activation, it may provide a quantitative measure of intrusive cognitive activity--the hallmark symptom of PTSD.

Selective processing of threat cues in panic disorder

A computerized Stroop color-naming paradigm was used to investigate attentional biases for selectively processing threat information in panic-disordered patients. Subjects named the colors of neutral words (e.g. TYPICAL), fear words (e.g. PANIC), bodily sensation words (e.g. HEARTBEAT), and catastrophe words (e.g. HEART ATTACK). To control for familiarity with threat concepts, we used clinicians who treat panic disorder as normal control subjects. In contrast to normal controls, panic patients exhibited greater Stroop interference for all threat words, especially those associated with catastrophe. Stroop interference waned during the course of the experiment, thereby indicating habituation to the semantic content of the cues. These findings suggest that panic disorder, like other anxiety disorders, is associated with an attentional bias for processing threatening information.

Selective processing of threat cues in posttraumatic stress disorder

Vietnam combat veterans with (n = 15) and without (n = 15) posttraumatic stress disorder (PTSD) performed a modified Stroop task in which they named the colors of neutral words (e.g., INPUT), positive words (e.g., LOVE), obsessive-compulsive disorder (OCD) words (e.g., GERMS), and PTSD words (e.g., BODYBAGS). In contrast to normal controls, PTSD patients took significantly longer to color-name PTSD words than to color-name neutral, OCD, and positive words. Because Stroop interference reflects involuntary semantic activation, it may provide a quantitative measure of intrusive cognitive activity--the hallmark symptom of PTSD.