Relationship between anosognosia and depression in aphasic patients

Depression and reduced awareness of illness (anosognosia) can be frequent complications following a brain lesion but the relationship between these two syndromes is still unclear. While some researchers suggested a protective function of anosognosia from depression, others deny a functional relationship. We investigated anosognosia and depression in a group of 30 left-brain-damaged patients using specialized methodology for aphasic patients. We observed that anosognosic patients showed levels of depression comparable to those of aware patients and that anosognosia was highly selective for specific deficits. Our findings suggest that reduced awareness for a deficit does not play a crucial role in mood disorder, whereas "simply" suffering for a deficit can per se increase the likelihood of depression. Moreover, whereas depressed and nondepressed patients did show a similar impairment on the nonverbal executive function test, almost all patients showed anosognosia associated with impairment on executive functions. Finally, depressed patients tend to deny or minimize their own mood disorder, confirming that anosognosia can also concern mood status and that self-rating measures for depression could be quite controversial.