Which symptoms are indicative of depression in epilepsy settings? An analysis of the diagnostic significance of somatic and non-somatic symptoms

Background: Depression is a common psychiatric co-morbidity in epilepsy. However, there have been no previous studies which have investigated the validity of individual symptoms for comorbid depression in epilepsy, in particular the diagnostic value of somatic and non-somatic symptoms.

Methods: Patients with epilepsy diagnosed in a specialist epilepsy clinic were approached and completed several self-reported mood scales, prior to or immediately after their neurology outpatient consultations. Symptoms of depression were elicited using PHQ-9, BDI-II and HADS scales, comprising a total of 44 self report questions. 266 patients returned complete questionnaires of whom 18.0% met criteria for DSM-IV major depression according to the WHO Major Depression Inventory.

Results: Against DSM-IV major depressive disorder (MDD), both somatic and non-somatic symptoms were valuable. The top five most useful questions relating to a diagnosis of MDD in epilepsy were "Moving or speaking so slowly that other people could have noticed" "Little interest or pleasure in doing things" "Feeling down depressed or hopeless" "Trouble concentrating on things such as reading" and "Feeling tired or having little energy." Four of these symptoms were rated as excellent initial screening questions for depression namely, "Moving or speaking so slowly that other people could have noticed" "Little interest or pleasure in doing things" "Feeling down depressed or hopeless" "Trouble concentrating on things such as reading." The item "Moving or speaking so slowly that other people could have noticed" from the PHQ9 was endorsed in about 90% of depressed patients with epilepsy but only about 6% of non-depressed patients.

Conclusion: These findings suggest that both somatic and non-somatic symptoms can be valuable when diagnosing depression in epilepsy and should be considered when designing scales for depression in epilepsy. Specific psychological symptoms and specific somatic symptoms are indicative of depression in epilepsy.