ABSTRACT
OBJECTIVES: To assess in further detail the specific form of motivational impairment influencing neuropsychological performance in depression-oversensitivity to perceived failure. The present study considers two questions: firstly whether this is specific to depression and secondly how the effect relates to clinical features. METHODS: Unipolar depressed patients and matched controls were assessed on two neuropsychological tests giving explicit performance feedback. The data were analysed in two separate studies to consider the questions above. The first study considered the specificity of the effect to depressed patients, using data on the same tests collected from other patient groups. The second study was a longitudinal assessment of the depressed patients on clinical recovery to determine whether the effect is specific to the depressed state. RESULTS: The effect was not seen in non-depressed patient groups, either neurological or psychiatric groups. The longitudinal study showed a residual abnormal response to negative feedback on clinical recovery. CONCLUSIONS: Abnormal response to negative feedback is specific to a primary diagnosis of depression and may be a trait rather than a state factor of the disorder. These results are discussed in relation to the putative neuropathology of depression and also to cognitive and behavioural accounts of the disorder. The findings presented here have important implications for establishing a link between mood and cognition in unipolar depression.
Subject(s)
Depressive Disorder/diagnosis , Depressive Disorder/psychology , Feedback , Neuropsychological Tests/statistics & numerical data , Adult , Affect , Cognition , Diagnosis, Differential , Female , Humans , Longitudinal Studies , Male , Mental Disorders/diagnosis , Middle Aged , Models, Psychological , Nervous System Diseases/diagnosis , Problem Solving , Reinforcement, PsychologyABSTRACT
The CANTAB battery of neuropsychological tests was used to compare the performance of 28 patients with unipolar depression with that of 22 age and IQ matched controls. The patients were impaired on almost all tests studied with deficits in pattern and spatial recognition memory, matching to sample, spatial span, spatial working memory and planning. Most of the patients showed at least some impairment and deficits were seen across cognitive domains. An important finding was the detrimental effect of failure on subsequent performance; having solved one problem incorrectly, patients were far more likely than controls to fail the subsequent problem. Superimposed on the general deficits, there were also specific deficits in executive tasks characteristic of frontostriatal dysfunction and deficits in mnemonic tasks characteristic of temporal lobe dysfunction. This combination of a specific form of motivational deficit, resulting in oversensitivity to negative feedback, and superimposed specific neuropsychological deficits were correlated with severity of depression. The most significant correlations were seen between mnemonic deficits and clinical rating scores. Comparisons of the deficits seen in the depressed patients in this study with other patient groups assessed with the CANTAB neuropsychological battery, showed that one of the hypotheses of the neuropsychological deficits in depression, that of "frontosubcortical' or "frontostriatal' dysfunction, was not supported. These findings are discussed in relation to the likely neural substrates of depression.
