Altered lateralization of cognitive processes in depressed women

The neuropsychology of depression and its implications for cognitive therapy

The past few years have witnessed a growing interest in the specialty of neuropsychology as well as continued support for cognitive therapy of depression. The purpose of this paper is the examination of the neuropsychology of depression and its implications for A. T. Beck's cognitive theory and therapy of depression ([1963] "Thinking and Depression: Idiosyncratic Content and Cognitive Distortions," Archives of General Psychiatry, Vol. 9, pp. 324-333; [1964] "Thinking and Depression," Archives of General Psychiatry, Vol. 10, pp. 561-571; [1967] Depression: Clinical, Experimental, and Theoretical Aspects, New York: Harper & Row). Specifically, the neuropsychological and cognitive theory and therapy literatures related to depression are reviewed followed by an integration of these areas. Neuropsychological evidence is presented that both supports cognitive theory and therapy of depression and helps explain why such therapy may prove ineffective in treating depression. Implications for clinical practice, including neuropsychological assessment of depressives, and potential future research directions are also provided.

Cerebral asymmetry in facial affect perception by women: neuropsychological effects of depressed mood

40 right-handed women, half of whom had been classified with depressed mood and the other half as nondepressed, participated in a tachistoscopic study of the influence of depressed mood on the cerebral hemispheric processing of Ekman and Friesen's 1976 happy, sad, and neutral emotional faces using a forced-choice reaction-time paradigm with only happy and sad alternatives as response manipulanda. The women with depressed mood were also characterized by elevated scores on both state and trait anxiety, suggestive of an anxious-depressive state with heightened arousal. Primary findings for the tachistoscopic data indicated that women with depressed mood as compared to nondepressed women displayed significantly faster reaction times to sad faces presented in the right visual field and happy faces presented in the left visual field. These results are suggestive of differential arousal of both the left and right cerebral hemispheres in this sample of anxious-depressed women and are discussed in light of arousal theory.

Hemispheric language lateralization in seasonal affective disorder and light treatment

Thirty-seven patients with seasonal affective disorder (SAD) and 25 control subjects were given a concurrent task, the verbal-manual interference paradigm, as a measure of hemispheric language lateralization. In winter, depressed patients showed a symmetrical interference pattern and control subjects experienced greater overall disruption in right-hand tapping during concurrent verbalization. Patients showed a greater left-hand tapping decrement compared with control subjects. Light treatment decreased the decrement in tapping with the left but not with the right hand in patients. After treatment, patients did not differ from controls in dual task interference effects. Patients also showed no difference from controls in summer. The difference between depressed subjects and controls in performance measures of laterality suggests that winter depression is associated with a shift of laterality from the left to the right. The winter abnormalities appear to be normalized by bright light.

Functional Hemispheric Asymmetry and Impaired vs. Optimal Psychological Functioning: Evaluation of a Model

The aim of this study was to propose and evaluate a model in which differential relationships are hypothesized between the nature and degree of functional hemispheric asymmetry (FHA), or neuropsychological differentiation on the one hand, and optimal or healthy personality functioning (OPF) vs. impaired personality functioning (IPF), on the other. FHA is operationalized by means of indices of the degree of left-hemisphere specialization for processing verbal information and the degree of right-hemisphere specialization for the recognition of emotional facial expressions. The degree of optimal personality functioning is operationalized with indices of self-actualization and autonomy, and the degree of impaired personality functioning with indices of the degree of anxiety and depression. The model was evaluated with the aid of the RAMONA program for path analysis with latent variables. The hypothesized model fits the data relatively well. A complex pattern of relationships emerged, in which specific qualities of FHA are associated with healthy vs. impaired personality functioning. From a systems perspective functional differentiation as well as functional integration seem to be important processes to consider when relationships between aspects of personality functioning and neuropsychological processes are investigated.

Asymmetry of recall in depression

We compared the verbal (auditory/semantic) and nonverbal (visual/configurational) recall of carefully defined depressed patients with a demographically matched control group of normal volunteers. Whereas controls were split as to whether their nonverbal recall exceeded or was inferior to their verbal recall, 89% of depressed patients demonstrated an asymmetry characterized by poorer nonverbal than verbal recall. Depressive subgroups (determined by clinical and psychoendocrine criteria) differed from controls, but not from each other, in demonstrating this asymmetry of recall. In contrast, depressed patients did not individually demonstrate an asymmetry between verbal and nonverbal recognition that differed from controls.

Event-related potentials in depression: influence of task, stimulus hemifield and clinical features on P3 latency

P3 latency, a brain event-related potential (ERP) correlate of stimulus evaluation time, was measured in 25 unmedicated depressed patients and 27 normal controls during auditory temporal and spatial discrimination tasks. Patients were divided into two subgroups, one having a typical major depression (melancholia or simple mood reactive depression) and one having an atypical depression. Typical depressives had abnormally long P3 latency for the spatial task but not the temporal task. They also showed an abnormal lateral asymmetry, with longer P3 latency for stimuli in the right hemifield than the left. In contrast, atypical depressives did not differ from normals in either respect. Longer P3 latency correlated with ratings of insomnia, while abnormal lateral asymmetry correlated with reduced right visual field advantage for syllables. The P3 latency findings point to a task-related slowing of perceptual decisions in a subgroup of depression.

Mouth asymmetry upon repeating words. A controlled study of bipolarly depressive patients in the remitted euthymic state

In view of previous research concerning the lateral bias of hand movements accompanying speech, it was postulated that patients with bipolar depression should differ from normal controls with respect to the asymmetry of mouth opening when repeating speech sounds. This hypothesis was confirmed. Our patient group, consisting of 29 remitted euthymic out-patients, did not show the greater right-sided mouth opening characteristic of the gender-matched normal controls.

A role for hemispheric asymmetry in human behavioral variability

A model is presented in which functional lateral specialization and selective hemisphere priming combine to provide a mechanism for behavioral variability. The model is tested and supported by two experiments in which lateral attentional priming produces significant reductions in between-subject and within-subject variability. These findings help us to understand the source of behavioral variability, broaden our knowledge of the gross structures and functions of the brain, provide information about the manipulation of perceived control, and offer a technique for increasing statistical power in a wide variety of research settings.

Right hemisphere involvement in depression: toward a neuropsychological theory of negative affective experiences

Several lines of inquiry provide converging evidence for a critical role for the right cerebral hemisphere in negative affective experiences. This research includes the assessment of affective consequences of both focal cerebral lesions and pharmacological inactivation of one or the other hemisphere, as well as experimental and physiological techniques assessing differential hemispheric activation. The specific nature of right hemispheric involvement is conceptualized as a tendency to become activated by aversive experiences, and once activated, to process stimuli in a manner consistent with the right hemisphere's more negative affective tone. A theory of right hemisphere involvement in depressive affect is presented in detail and its relevance to clinical phenomena, e.g., the co-occurrence of depression and pain, and sex differences in depression, is examined, as is congruence with cognitive theories of depression.

Verbal and non-verbal recall by depressed and euthymic affective patients

This study uses matched-tasks methodology in order to test memory function in depressed and euthymic patients with major affective disorder. Neither drug-free depressed patients nor lithium-treated euthymic patients show a differential deficit in verbal versus non-verbal recall. However, while euthymic patients show no memory impairment, drug-free depressives do show poor memory functioning. The results support the view that memory deficits observed in affective patients in the depressed state are transient, secondary manifestations of depression and are neither indicative of underlying organic pathology, nor of abnormal hemispheric laterality. This suggests that memory impairment in depression can be treated by treating depressive symptoms, both chemically and behaviourally. The results also support the view that prophylactic lithium treatment has no adverse effects on these memory tasks.

Hemispheric lateralization of functions related to emotion

We have reviewed the evidence that processes and functions related to perception and expression of emotions are represented asymmetrically in the cerebral hemispheres. The literature describes three possible aspects of emotional lateralization: that emotions are better recognized by the right hemisphere; that control of emotional expression and related behaviors takes place principally in the right hemisphere; and that the right hemisphere is specialized for dealing with negative emotions, while the left is specialized for dealing with positive emotions. Evidence for the three hypotheses derives from methodologically diverse studies in unimpaired, brain-lesioned, and mood-disordered populations. Relatively little of the work has been precisely replicated, and conclusions rest on parallel lines of evidence from diverse sources. The present level of knowledge suggests a model of emotional control based on interactive inhibition between a right negatively biased and left positively biased hemisphere. However, the details of such a model, including the precise conditions under which emotion-related functions are lateralized, and the mechanisms of such lateralization have yet to be elucidated.

Sex differences in brain organization: implications for human communication

This article reviews current knowledge in two major research domains: sex differences in neuropsychophysiology, and in human communication. An attempt was made to integrate knowledge from several areas of brain research with human communication and to clarify how such a cooperative effort may be beneficial to both fields of study. By combining findings from the area of brain research, a communication paradigm was developed which contends that brain-related sex differences may reside largely in the area of communication of emotion.

Gender differences in antidepressant and activating drug effects on self-perceptions

Gender difference in neuropharmacologic responsivity have received surprisingly little attention in clinical research. In view of well-known gender differences in the prevalence of depression, we wondered whether men and women would respond differently to antidepressants or to an activational drug known to predict antidepressant response. Using clorgyline and D-amphetamine in 2 small samples, we illustrated several methodological approaches for examining possible gender-linked differences in the effects of these drugs on self-perceptions. Gender-linked differences in cognitive-perceptual processes may, in turn, be linked to differences in encoding or consolidating information about our experiences into our self-image for later recall.