Are Depression and Cognitive Performance Related in Temporal Lobe Epilepsy?

Abstract

SUMMARYPurpose: The degree to which depression interacts with the cognitive deficits of epilepsy to alter cognitive skill and general functioning is unknown. Depression has significant negative effects on adaptive functioning including cognitive skills. Temporal lobe epilepsy (TLE) patients are known to possess cognitive dysfunction. Thus, TLE patients who are depressed may suffer a double burden of cognitive deficits. Methods: We examined whether depressed patients show increased cognitive deficits relative to nondepressed TLE patients (n = 59). We then sought to determine if this effect varied for left versus right TLE patients utilizing preoperative depression and neuropsychological data. To accurately study the lateralization of any observed effects, we selected only patients with definitive evidence of unilateral pathology and seizure focus and utilized a two-year seizure-free postsurgical outcome to capture this.Results: The data suggested that cognitive performance was not related to depression, and that depression did not reliably mediate the cognitive presentation of either our left or right TL patients. The notion of a double burden on cognition did not receive support from our data. The data did produce the expected advantage on verbal memory measures for right TLE patients. Conclusions: The reasons for the limited statistical effects are discussed and issues in unraveling the causal relationships between depression, cognition, and TLE are considered. We discussed the potential role depression may play in the cognitive skills of TLE patients, but the major implication is that depression and neurocognitive performance appear to bear a limited relationship in the context of TLE. KEY WORDS: Temporal lobe epilepsyDepression-Neuropsychological deficits-Mood disorders-Cognition.Depression is a very common mood disturbance in epilepsy. The prevalence of depression in epilepsy ranges from 20% to 55% in patients with recurrent seizures and from 3% to 9% in patients with controlled epilepsy (Jacoby et al., 1996). Patients with temporal lobe epilepsy (TLE) tend to have a higher rate of affective disorders than other epilepsies (Kanner and Nieto, 1999) that are unrelated to seizure frequency or intractability of the seizures (Airaksinen et al., 2004). Some investigators have suggested that 20% of TLE patients become depressed

Resting-state functional connectivity in epilepsy

“…Up to 20-55% of TLE patients suffer from depression [46][47][48]. Indeed, studies have strongly supported the notion that depression in TLE is caused by pathological epileptic activity [49].…”

Distinct Types of White Matter Changes Are Observed after Anterior Temporal Lobectomy in Epilepsy

“…Depressive Disorders were allowed in the patient sample, given the high co-morbidity of depression and epilepsy [32]. Patients with mental retardation (Full-Scale IQ <70) who were likely to be unable to cooperate with the MRI examination were also excluded.…”

The Contribution of Cognitive Networks to Depression in Epilepsy

“…While some studies show that depressed patients with epilepsy show depression-related cognitive biases, worse cognition, and greater risk of cognitive decline after epilepsy surgery than euthymic patients (e.g., [45][46][47], others fail to show such a relationship. (e.g., 48). This variability supports the contention that altered cognitive networks are linked to depressive symptoms in epilepsy only in certain subgroups.…”