Individuals with temporal lobe epilepsy (TLE) are at higher risk for developing anxiety and depressive symptoms compared to the general population. Both anxiety and depressive symptoms have been previously associated with structural and functional abnormalities of the hippocampus and amygdala due to recurrent epileptic seizures. Some studies have found a relationship between greater hippocampus and amygdala atrophy and greater depressive and anxiety symptom severity. Conversely, amygdala and hippocampus enlargements have been found in patients with psychosis and affective aggression. Increased amygdala volumes have also been linked to anxiety disorders in adults. The relationship between structural abnormalities and depression/anxiety symptoms seems to be a quadratic relationship, where both amygdala atrophy and enlargement can be pathological signatures of anxiety vulnerability. Abnormal functional connectivity of these limbic structures has also been associated with anxiety and depressive symptoms. It remains unclear whether the increase in anxiety and depression is due to organic factors such as structural abnormalities and other seizure related damages, or due to situational factors such as living a life with recurrent seizures. Regardless of the origin, clinicians should recognize this relationship in order to detect and diagnose any depression and anxiety in patients with TLE in order to provide proper treatment.
Doucet, G.E., Skidmore, C., Sharan A.D., Sperling M.R., & Tracy, J.I. (2013). Functional connectivity abnormalities vary by amygdala subdivision and are associated with psychiatric symptoms in unilateral temporal epilepsy. Brain and Cognition, 83, 171-182.
The amygdala has been described as a structure affected by mesial temporal lobe epilepsy (MTLE). Indeed, it is suggested that amygdala abnormalities are related to the co-morbid depression and anxiety reported in MTLE. In this context, we investigated the relation between functional connectivity (FC) emerging from this structure in fMRI and depression and anxiety levels reported in MTLE patients. We focused on resting-state BOLD activity and evaluated whether FC differences emerge from each of three amygdala subdivisions (laterobasal, centromedial and superficial) in left and right MTLE groups, compared with healthy controls. Results revealed significant differences between patient groups and controls. Specifically, the left MTLE group showed abnormal FC for the left-sided seeds only. Furthermore, regardless of the seed, we observed more reliable differences between the right MTLE group and controls. Further analysis of these results revealed correlations between these impaired connectivities and psychiatric symptoms in both MTLE groups. Opposite relations, however, were highlighted: the more depressed or anxious the right MTLE patients, the closer their FC values approached controls; whereas the less anxious the left MTLE patients, the closer their FC values were normative. These results highlight how MTLE alter FC emerging from the limbic system. Overall, our data demonstrate that right TLE has a more maladaptive impact on emotion-related networks, in ways specific to the amygdala region, and the emotion symptom involved, than left TLE.
- Dr. Dan McLaughlin discusses the risk of anxiety and depression in individuals with TLE and the importance of proper diagnosis and treatment. https://youtu.be/SZnXqBMRSqo
- Overview of the link between epilepsy and depression and anxiety. https://youtu.be/7B71ChCS_-w
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