Cognitive functioning and cortisol profiles in first episode major depression

Major Depressive Disorder (MDD) is often associated with high levels of stress and disturbances in the Hypothalamic Pituitary Adrenal (HPA) system, yielding high levels of cortisol, in addition to cognitive dysfunction. Previous studies have shown a relationship between cortisol profile and cognitive functioning in recurrent MDD in general. More specifically, the association between hypercortisolism and cognitive functioning, such as memory and Executive Functioning (EF), and also more recently cortisol suppression has been explored. However, no studies have investigated these relationships in patients diagnosed with first episode MDD. The aim of the present study was to examine the relationship between cortisol levels before and after the Dexamethasone suppression test (DST) and cognitive function in first episode MDD patients. Twenty‐one patients meeting the DSM‐IV criteria for a first episode of MDD diagnosis were included in the study. The control group was matched for age, gender and education level. Cortisol was measured in saliva collected with Salivette sampling devices. Saliva samples were collected 4 times during a 24 hours period over two consecutive days: at awakening, after 45 minutes, after 7 hours and at 11 pm. Dexamethasone (1.0 mg) was given orally on Day 1 at 11 pm. The neuropsychological test battery consisted of standardized tests measuring executive functioning (EF) and memory functioning. Cortisol levels did not differ significantly between patients and controls on Day 1, except for the last sample before Dexamethasone administration, where the control group showed higher levels. Both groups showed suppression after Dexamethasone. On Day 2 there was a significant difference between groups at the third sample, showing a significantly lower level in the control group, suggesting that the controls have a more effective suppression profile than the patients. There were no significant correlations between cortisol levels before or after Dexamethasone and cognitive measures. The results indicate impairment on HPA‐axis functioning in first episode MDD patients, with less suppression functioning compared to healthy controls, but no relationship between cortisol profile and cognitive functioning in EF or Memory.     

Cognitive deficits in developmental disorders

The existence of specific developmental disorders such as dyslexia and autism raises interesting issues about the structure of the normally developing mind. In these disorders distinct cognitive deficits can explain a range of behavioural impairments and have the potential to be linked to specific brain abnormalities. One possibility is that there are specific mechanisms dedicated to particular types of information processing. These mechanisms may function independently of more general information processing systems and may have a distinct anatomical basis in the brain.     

Cognitive deficits related to major organ failure: The potential role of neuropsychological testing

Until recently, little attention has been paid to the possibility of cognitive deficits in patients with disease or failure of major organs such as the liver, kidney, or heart. However, there is a growing awareness that major organ failure often has neuropsychological sequelae. These sequelae may at times be quite subtle and not detectable under gross. examination. Nevertheless, even subtle deficits may have a major impact on adherence to medical regimens, psychosocial adjustment, and quality of life of patients. Neuropsychological assessment has a potentially valuable role to play both in research and in clinical work. It can be useful in adding to our knowledge of the cognitive effects of various types, severity and duration of major organ disease, as well as sequelae associated with treatment. It also is a potentially valuable clinical tool for identifying cognitive deficits that will affect the quality of life and probability of survival for organ failure patients.     

Cognitive inhibition in depression

Cognitive inhibition is a key mechanism in the regulation of emotion. There is emerging evidence that depression is characterized by deficits in the inhibition of mood-congruent material. These deficits could result in prolonged processing of negative, goal-irrelevant aspects of presented information thereby hindering recovery from negative mood and leading to the sustained negative affect that characterizes depressive episodes. Indeed, it has been suggested that deficits in cognitive inhibition lie at the heart of memory and attention biases in depression, and set the stage for ruminative responses to negative events and negative mood states. A ruminative response style results in a heightened vulnerability to experience episodes of major depression. Recent research has demonstrated that deficient inhibition of negative material is associated with heightened rumination. In this article, we review the depression literature with a focus on studies that investigate cognitive inhibition in depressed participants and in participants who report a history of major depressive episodes. In addition, we summarize neurobiological findings that indicate a strong relation between depression and deficits in inhibition and we take a closer look at the relation of inhibition, rumination and mood regulation.     

Cognitive biases and depression

Compared symptomatically depressed, clinically remitted, and normal controls using cognitive measures designed to be traitlike and statelike in cross-sectional and longitudinal designs, respectively. Remitted depressives and normal subjects did not differ in their attributional biases, endorsement of dysfunctional attitudes, or interpretation of schema-relevant ambiguous events, but both groups differed from symptomatic depressives. Depressive episodes thus affect cognition, but cognitions measured by self-reports are more statelike than traitlike.     

Interference resolution in major depression

In two experiments, we investigated individual differences in the ability to resolve interference in participants diagnosed with major depressive disorder (MDD). Participants were administered the “Ignore/Suppress” task, a short-term memory task composed of two steps. In Step 1 (“ignore”), participants were instructed to memorize a set of stimuli while ignoring simultaneously presented irrelevant material. In Step 2 (“suppress”), participants were instructed to forget a subset of the previously memorized material. The ability to resolve interference was indexed by response latencies on two recognition tasks in which participants decided whether a probe was a member of the target set. In Step 1, we compared response latencies to probes from the to-be-ignored list with response latencies to nonrecently presented items. In Step 2, we compared response latencies to probes from the to-be-suppressed list with response latencies to nonrecently presented items. The results indicate that, compared with control participants, depressed participants exhibited increased interference in the “suppress” but not in the “ignore” step of the task, when the stimuli were negative words. No group differences were obtained when we presented letters instead of emotional words. These findings indicate that depression is associated with difficulty in removing irrelevant negative material from short-term memory.     

Cognitive and marital factors in depression

The current investigation examines three groups of wives: (1) a group of nondepressed, nondiscordant community wives; (2) a group of nondepressed, discordant clinic wives; and (3) a group of depressed, discordant clinic wives. Groups were formed on the basis of structured interview responses and responses to a self-report inventory of depressive symptomatology. To be classified as depressed, wives were required to meet DSM III criteria for depression according to interview data and to exceed a Beck Depression Inventory score of 14. Both clinic groups showed equal levels of marital discord. Both nondepressed groups showed equally few cognitive errors. Accordingly, comparisons of these three groups allow us to test current interpersonal and cognitive theories of depression. The level of closeness in the marriage differentiated the depressed, discordant from the nondepressed, discordant wives despite their equal levels of overall marital discord. The level of depressive symptomatology was greater for the nondepressed clinic wives than it was for the community wives despite their equal levels of cognitive errors. Both closeness in the marriage and cognitive errors accounted for the unique variance in level of depression. Implications for current interpersonal and cognitive accounts of depression are discussed.Support for this research came in part from NIMH Grant 38390-02. Portions of this paper were presented at the 25th Annual Convention of the American Association for the Advancement of Behavior Therapy.     

Cognitive deficits in compulsive checkers: An exploratory study

Compulsive-checking behavior can be conceptualized as resulting, in part, from a memory failure. In order to determine if memory difficulties are associated with compulsive checking, the performance of college-student checkers were compared with the performance of non-checkers on a number of cognitive tasks hypothesized to be relevant to understanding checking behavior. Using the Checking and Cleaning subscales of the Maudsley Obsessional-Compulsive Inventory, four groups of subjects were identified: (1) Cleaning Checkers (N = 13); (2) Noncleaning Checkers (N = 13); (3) Cleaning Noncheckers (N = 13); and (4) Noncleaning Noncheckers (N = 15). It was hypothesized that the cognitive deficits studied would characterize individuals with cheeking compulsions, but not persons with non-checking compulsions (i.e. Cleaning Noncheckers) or normal controls (i.e. Noncleaning Noncheckers). Compulsive checkers were found to have a poorer memory for prior actions than non-checkers and were also found to underestimate their ability at distinguishing memories of real and imagined events, a process referred to as reality monitoring. Both of these deficits were specific to compulsive checkers and can be viewed as contributing to the likelihood that an individual will engage in checking behavior. If an individual has difficulty in recalling whether an intended action has been executed, they may be inclined to engage in checking behavior to insure the intended action is carried out. Similarly, a tendency to underestimate reality-monitoring ability could result in increased checking behavior as the individual attempts to reduce his/her uncertainty over whether a previous behavior actually occurred or merely was thought to occur. It is concluded that the study of cognitive deficits in compulsive checking is a potentially fruitful avenue for further inquiry.     

Cognitive and attentional deficits in children vulnerable to psychopathology

Cognitive and attentional deficits were assessed in children with either a schizophrenic, an affectively disordered or a normal parent. The children were grouped both by their parents' DSM-II diagnoses (broadly defined group of schizophrenics and heterogeneous group of depressives)and by a new set of diagnoses (narrowly defined group of schizophrenics, unipolar depressive group and bipolar group). Children whose parents met the more stringent criteria for schizoprhenia performed somewhat more deviantly than children whose parents met only DSM-II criteria. In addition, the importance of splitting the heterogeneous depressive group into more homogeneous subgroups is indicated by the findings that children of unipolar parents generally could not be distinguished from children whose parents are schizophrenic. On the other hand, children of bipolar parents performed reliably better than children of schizophrenics. These findings are viewed within the context of current high-risk studies and psychological deficit literature and suggest that diagnostic issues require more attention by researchers in these areas.This research was supported by Grant MH 21145 from the National Institute of Mental Health. The authors are indebted to Lina Jandorf for assistance in testing the children and with the data analyses.     

Cognitive aspects of chronic depression

Previous research on chronic depression has focused on its link with other mood disorders and Axis II personality disorders. However, there are few data examining whether the cognitive perspective applies to this condition. In this cross-sectional study, 42 outpatients with chronic depression were compared with 27 outpatients with nonchronic major depressive disorder and 24 never psychiatrically ill controls on cognitive variables thought to be related to vulnerability to depression (e.g., dysfunctional attitudes, attributional style, a ruminative response style, and maladaptive core beliefs). Both depressed groups were more elevated than a never-ill comparison group. However, chronically depressed individuals were generally more elevated on measures of cognitive variables than those with major depressive disorders even after controlling for mood state and personality disorder symptoms.     

Rumination and attention in major depression

Up until recently, it had been assumed that attentional biases for negative information do not exist in depression. However studies using post-conscious exposure durations have produced contradictory results. The limitations of common attentional tasks, suitability of stimulus materials and differences in stimulus duration times may have contributed to these inconsistencies. We aimed to address many of these issues and examine attentional responses in major depression at two post-conscious exposure times. We also investigated possible roles for rumination and distraction in increasing and lessening attentional biases for negative information. We used a fully controlled experimental design to test the effects of both induced and trait rumination and distraction on attention in patients with major depression and healthy controls. Attention was assessed using the dot-probe task. The findings revealed an attentional bias for negative information in depressed patients only at the longer post-conscious exposure duration. Furthermore although this bias was not influenced by either induced or trait distraction, it was related to trait rumination. Overall, the results showed that depression is associated with a strategic attentional bias towards negative information and that this bias is stronger in individuals who habitually ruminate.     

Pessimistic self-preoccupation, performance deficits, and depression

Three studies are presented testing a model of the cognitive performance deficits shown in depression. The model proposes that such deficits occur as an interaction of expectancy and focus of attention variables, that is, in the presence of both low expectancy of success and high self-focus. Study 1 was a pilot study which documented that depressed undergraduates evidence poorer anagram performance, greater self-focus, and lower pretask expectancies than do nondepressed subjects. Study 2 showed that nondepressed undergraduates evidence performance deficits only when both expectancy is lowered and self-focus is increased. Study 3 suggested that depressed undergraduates' performance deficits are overcome either by lowering self-focus or by raising expectancy. Discussed are discrepancies between self-report and performance data, the relevance of these studies to the test anxiety literature, the need to integrate literature concerning the effects of depression, anxiety, and self-esteem on performance, and how the interactive roles of positive expectancy and focus of attention may be related to effective coping in a variety of situations.     

Cognitive processing deficits in reading disabilities: A prefrontal cortical hypothesis

Much research investigating the neuropsychological underpinnings of reading disabilities has emphasized posterior brain regions. However, recent evidence indicates that prefrontal cortex may also play a role. This study investigated cognitive processes that are associated with prefrontal and posterior brain functions. Subjects were 12-year-old reading disabled and nondisabled boys. Discriminant analysis procedures indicated that measures of prefrontal functions distinguished between the two groups better than measures of posterior functions. The results suggest that reading disabled boys have difficulty with cognitive processes involving selective and sustained attention, inhibition of routinized responses, set maintenance, flexibility in generating and testing alternative hypotheses, and phonemically based language production.     

Ambivalence over emotional expression in major depression

High ambivalence over the expression of emotions (AEE) has consistently been associated with high levels of depression in previous research. However, there is a lack of studies examining this construct and its associations in a clinical sample of patients with major depressive disorder (MDD). Therefore, the present study compared 76 MDD with 77 non-depressed controls (NC) regarding AEE. As expected, MDD reported greater AEE as compared to ND. Furthermore, levels of AEE and levels of depression were positively correlated in the MDD group. These findings extend previous work and underline the importance of AEE as a central construct in depression. Targeting AEE in treatments of depression may help to modify maladaptive interpersonal patterns of emotional expression.     

Intrusive images and memories in major depression

Individuals with current major depression were interviewed to investigate the prevalence of distressing intrusive mental imagery among depressed patients and study the phenomenology of these intrusions. Of the 39 currently depressed patients, 17 experienced some form of repetitive intrusive imagery (i.e., either an intrusive memory or image), with intrusive memories being more common than images. The intrusive imagery was experienced as highly uncontrollable and interfered significantly with patients' everyday lives. The intrusions were experienced with a sense of 'nowness', as well as physical and emotional re-experiencing. Despite high levels of re-experiencing, levels of dissociation were very low. The intrusive imagery was in some patients part of a wider network of key defining autobiographical memories, consistent with the idea that it is likely to play a significant role in maintaining the patient's depressive mood. Interventions targeting these intrusions could potentially result in a positive shift in depressed mood.