Sarah E. Altman

Subthreshold conditions as precursors for full syndrome disorders: a 15-year longitudinal study of multiple diagnostic classes.

BACKGROUND There has been increasing interest in the distinction between subthreshold and full syndrome disorders and specifically whether subthreshold conditions escalate or predict the onset of full syndrome disorders over time. Most of these studies, however, examined whether a single subthreshold condition escalates into the full syndrome form of that disorder. Equally important, though, is whether subthreshold conditions are likely to develop other full syndrome disorders and whether these associations are maintained after adjusting for comorbidity. METHODS A 15-year longitudinal study of subthreshold psychiatric conditions was conducted with 1,505 community-drawn young adults. We examined whether 1) subthreshold major depression, bipolar, anxiety disorders, alcohol use, substance use, conduct disorder and/or ADHD were precursors for the corresponding (homotypic) full syndrome disorder; 2) subthreshold conditions were precursors for other (heterotypic) full syndrome disorders; and 3) these homotypic and heterotypic precursors persisted after adjusting for comorbidity. RESULTS Subthreshold major depression, anxiety, alcohol use, substance use, and conduct all escalated into their corresponding full syndrome and nearly all homotypic developments were maintained after adjusting for comorbid subthreshold and full syndrome conditions. Many heterotypic associations were also observed and most remained after controlling for comorbidity, particularly among externalizing disorders (e.g., alcohol, substance, conduct/antisocial personality disorder). CONCLUSIONS Many subthreshold conditions have predictive validity as they may represent precursors for full syndrome disorders. Alternatively, dimensional conceptualizations of psychopathology which include these more minor conditions may yield greater validity. Subthreshold conditions may represent good targets for preventive interventions.

What is the association between obsessive-compulsive disorder and eating disorders?

Because eating disorders (EDs) and obsessive compulsive disorder (OCD) co-occur at high rates and can have functionally similar clinical presentations, it has been suggested that both constructs might be part of a common spectrum of disorders. Identifying the relationship between EDs and OCD may lead to the discovery of important shared core disease processes and/or mechanisms for maintenance. The objective of this paper is to understand the relationship between EDs and OCD by systematically reviewing epidemiological, longitudinal and family studies guided by five models of comorbidity posited by Klein and Riso (1993) and others. Though this literature is relatively small, the preponderance of evidence from these studies largely suggests that OCD/ED co-occur because of a shared etiological relationship. Limitations to extant literature, and suggestions for future research are discussed.

Biomarkers of Threat and Reward Sensitivity Demonstrate Unique Associations With Risk for Psychopathology

Two emotional/motivational constructs that have been posited to underlie anxiety and depressive disorders are heightened sensitivity to threat and reduced sensitivity to reward, respectively. It is unclear, though, whether these constructs are only epiphenomena or also connote risk for these disorders (and relatedly, whether they connote risk for separate disorders). Using family history of psychopathology as an indicator of risk, the present study examined whether biomarkers of sensitivity to threat (startle potentiation) and reward (frontal EEG asymmetry) were associated with similar or different familial liabilities. In addition, the present study examined whether these biomarkers were associated with risk independent of proband DSM-IV diagnosis. One-hundred and seventy-three individuals diagnosed with panic disorder (PD), early onset major depressive disorder (MDD), both (comorbids), or controls completed two laboratory paradigms assessing sensitivity to predictable/unpredictable threat (measured via startle response) and reward (measured via frontal EEG asymmetry during a gambling task). Results indicated that across all participants: (a) startle potentiation to unpredictable threat was associated with family history of PD (but not MDD); and (b) frontal EEG asymmetry while anticipating reward was associated with family history of MDD (but not PD). Additionally, both measures continued to be associated with family history of psychopathology after controlling for proband DSM-IV diagnosis. Results suggest that the proposed biomarkers of sensitivity to unpredictable threat and reward exhibit discriminant validity and may add to the predictive validity of the DSM-IV defined constructs of PD and MDD, respectively.

Effects of Predictability of Shock Timing and Intensity on Aversive Responses

An important characteristic of aversive stimuli that determines emotional responses is whether the stimuli are predictable. Human laboratory studies in this area have typically operationalized predictability as being able to predict the occurrence of aversive events, but animal studies suggest that being able to predict other characteristics of the stimuli may also play a role in aversive responding. To examine this, the present study examined two characteristics: the timing and intensity of aversive stimuli. Specifically, participants were randomly assigned to receive shocks that were either predictable or unpredictable in terms of when they would occur (timing) and/or their intensity. Indicators of aversive emotional responses were EMG startle responses and subjective anxiety ratings. Results revealed that aversive responding was elevated for unpredictable timing and intensity suggesting that the predictability of both characteristics play a role in aversive responding (though the effects for timing were stronger). In sum, the anxiogenic effects of unpredictability may generalize to situations beyond unpredictable timing.

Effect of Acute Tryptophan Depletion on Emotions in Individuals with Personal and Family History of Depression following a Mood Induction

Background: Acute tryptophan depletion (ATD) has shown depletion-specific increases in depressed mood and overall depressive symptoms, especially in those with a family history and in remitted patients. However, its effect on a broad range of emotions beyond depressed mood has been inconsistent, and studies have rarely employed a negative mood induction. Method: The present double-blind study administered tryptophan-depleted and taste-matched placebo challenge drinks to individuals with a past diagnosis and family history of depression (i.e. depression-vulnerable subjects) and controls in order to investigate the effect of ATD on positive affect, anxiety, anger and depressed mood following a negative mood induction. Results: Certain aspects of positive affect decreased due to ATD in the depression vulnerables but not in the controls. No differential effects were found on depressed mood and anxiety. Conclusions: A stress-induced blunted hedonic capacity may increase vulnerability to ATD and may be a core emotional abnormality in depression. Additionally, serotonin may have a stronger influence on positive affect than on other depression-related emotions during periods of stress.

Are individual differences in appetitive and defensive motivation related? A psychophysiological examination in two samples

Appetitive and defensive motivation account for a good deal of variance in personality and mental health, but whether individual differences in these systems are correlated or orthogonal has not been conclusively established. Previous investigations have generally relied on self-report and have yielded conflicting results. We therefore assessed the relation between psychophysiological indices of appetitive and defensive motivation during elicitation of these motivational states: specifically, frontal electroencephalogram asymmetry during reward anticipation and startle response during anticipation of predictable or unpredictable threat of shock. Results in a sample of psychopathology-free community members (n=63), an independent sample of undergraduates with a range of internalising symptoms (n=64), and the combination of these samples (n=127) revealed that differences in responding to the two tasks were not significantly correlated. Average coefficients approached zero in all three samples (community: .04, undergraduate: −.01, combined: .06). Implications of these findings for research on normal and abnormal personality are discussed.

The relation between symptoms of bulimia nervosa and obsessive-compulsive disorder: a startle investigation.

Bulimia nervosa (BN) and obsessive-compulsive disorder (OCD) co-occur at greater rates than chance and may have shared mechanisms of dysfunction. One of these proposed mechanisms is a hyper-responsive aversive system as indicated by heightened startle response to aversive stimuli. The present study examined this hypothesis using 2 types of aversive stimuli: disorder specific (e.g., high-caloric food pictures for BN, contamination pictures for OCD) and nondisorder specific (e.g., knife). Temporal parameters of aversive responding were also examined by assessing startle response in anticipation of and following picture presentation. The sample consisted of 114 undergraduate women selected to have a broad range of BN and/or OCD symptomatology. OCD symptoms were associated with increased startle potentiation during the anticipation and presentation of contamination pictures, and BN symptoms were associated with increased startle potentiation during disorder-related contamination pictures (e.g., sink, toilet). BN symptoms were also associated with increased startle potentiation during and following the presentation of food pictures (though the former effect was only a trend). Additionally, the interaction of BN and OCD symptoms was associated with elevated startle responding during the presentation of contamination and threat stimuli. Overall, the present study provides evidence that BN and OCD symptoms are associated with heightened aversive responding to disorder-specific stimuli, and comorbid BN and OCD symptoms are associated with heightened aversive responding across disorder-specific and nonspecific aversive stimuli. Clinical and theoretical implications are discussed.