Cognitive correlates of apathy in traumatic brain injury.

Objective: To investigate the relation between apathy and cognitive deficits in patients with severe traumatic brain injury (TBI).

Background: Apathy defined as reduced goal-directed behavior due to lack of motivation constitutes a major neuropsychiatric symptom following TBI. According to definition, apathy should not be associated with global cognitive reduction, but rather with specific areas of cognitive dysfunction.

Methods: results from the Apathy Evaluation Scale (AES) and a comprehensive neuropsychologic assessment were collected in up to 53 patients with severe TBI. Neuropsychologic tests were organized in the following seven areas of cognitive function: acquisition and memory, attention span, executive function, psychomotor speed, verbal skills, nonverbal skills, and motor speed.

Results: Apathy score was significantly correlated with reduced performance on acquisition and memory, psychomotor speed, and executive functions. A principal component analysis showed that these specific areas of cognitive functions clustered together with the cognitive dimension of apathy, not with behavioral or emotional aspects of apathy.

Conclusions: Apathy is associated with specific cognitive deficits related to frontal lobe dysfunction. The results are in accordance with the definition of apathy and confirm apathy-cognitive function relationships reported in other neurologic populations.