The association between the disruption of motor imagery and the number of depressive episodes of major depression.

BACKGROUND: Mental rotation performance may be used as an index of mental slowing or bradyphrenia, and may reflect, in particular, speed of motor preparation. Previous studies suggest depressive patients present the correlates of impaired behavioural performance for mental rotation and psychomotor disturbance. The aim of this study is to compare the mental rotation abilities of patients with a first episode of depression, recurrent depression and healthy control subjects with regard to hand tasks. METHODS: We tested 32 first episode of depression, 38 recurrent depression and 36 healthy control subjects by evaluating the performance of depressed patients with regard to the hand mental rotation tasks. RESULTS: First, the first episode and recurrent depression subjects were significantly slower and made more errors than controls in mentally rotating hands. Second, the first depressive episode but not the recurrent depression displayed the same pattern of response times to stimuli at various orientations relative to control subjects in the hand task. Third, in particular, recurrent depression subjects were significantly slower and made more errors during the mental transformation of hands than first depressive episode relative to control subjects and the differences were significantly larger in female than male subjects in the mental rotation hand task. LIMITATIONS: Patients were on antidepressant medication. CONCLUSIONS: These results suggest that the impaired behavioural performance for mental representation processing are related to the number of previous episodes. Moreover, the recurrent major depressive episodes may contribute to the reinforcement of cognitive impairments and further the development or maintenance of mental representation dysfunctions, especially in female patients. A deficit on mental rotation in the depressive patients may be potential biomarkers for recurrence chronically.

[Comparison of mental rotation ability for depressive disorder and schizophrenia].

OBJECTIVE: To compare the mechanism of depressive disorder and schizophrenia' mental rotation ability so as to provide specific objective clinical indicators for identifying mental illness. METHODS: Thirty depressive disorder (15 males, 15 females), 30 schizophrenia (15 males, 15 females) and 28 healthy participants (14 males, 14 females) were tested to perform mental rotation tasks with the letter F and R graphics. The subjects were required to decide whether the stimulus was a normal or a mirror version of an alphabet letter presented in different views and angular orientations. The mouse left key was pressed for a normal and the mouse right button for a mirror. RESULTS: (1) Error rate: As compared with the normal control group (normal: 29% ± 10%, mirror: 32% ± 3%), the normal error rate was significantly higher while the mirror error rate significantly lower in depressive disorder (normal: 31% ± 13%, mirror: 22% ± 4%, P < 0.01); the normal error rate was significantly lower while the mirror error rate significantly higher in schizophrenia (normal: 27% ± 9%, mirror: 42% ± 2%, P < 0.01). (2) Normal reaction rate: As compared with the normal control group (50% ± 9%), the normal reaction rate was significantly lower in depressive disorder (38% ± 12%, P < 0.01) and significantly higher in schizophrenia (60% ± 9%, P < 0.01). (3) Response time: As compared with the normal control group (normal (602 ± 25) ms, mirror (606 ± 14) ms), the normal and mirror response durations were both significantly longer in depressive disorder(normal (653 ± 23) ms, mirror (714 ± 13) ms, P < 0.01) while significantly shorter in schizophrenia (normal (571 ± 18) ms, mirror (587 ± 11) ms, P < 0.01). CONCLUSION: Normal mental rotation ability is severely impaired in depressive disorder, but its mirror counterpart becomes compensated. In schizophrenia, mirror mental rotation ability is severely impaired, but its normal counterpart becomes compensated. It hints that normal and mirror rotation ability may be interchangeable so as to serve as a state index. The impairment of mental rotation ability impaired can be used as specific objective clinical indicators of identifying mental illness.