The issue of phenomenology of depression in epilepsy is very much a matter of debate. Betts (1974) reported that patients with epilepsy and depression manifested more endogenous features, while Mulder and Daly (1952) commented on a more reactive nature of depression. The spectrum is likely to be large. In general terms, it is reasonable to hypothesize that patients with epilepsy can experience forms of mood disorders identical to those of patients without epilepsy. However, it is equally reasonable to assume that the underlying brain pathology can influence the expression of mood disorder symptoms, making less evident some aspects or emphasizing others.
The comorbidity between mood and anxiety disorders could be a potential example of such a peculiarity (see Chapter 16). Comorbid anxiety symptoms have been identified in 73% of patients with epilepsy and depression (Robertson et al., 1987 , Jones et al., 2005a). However, it is still unknown whether this is an association identical to that described in primary mood disorders or a comorbidity typical of chronic illnesses (where anxiety is present, with irritability and generalized turmoil), or if it is distinctive only of epilepsy and interlinked with the underlying brain pathology. The recognition of comorbid anxiety symptoms is very important clinically, since they may worsen the quality of life of depressed patients and significantly increase the risk of suicide (Kanner, 2006).
One of the main reasons in favor of the existence of an epilepsy-specific affective disorder comes from the clinical observation that the psychopathology often has unique manifestations that are poorly reflected by conventional classification systems such as DSM-IV and ICD-10 (Krishnamoorthy et al., 2007) . Mendez et al. (1986) investigated the clinical semiology of depression in 175 patients with epilepsy, and reported that 22% could be classified as having atypical features. In particular, classic endogenous-type depressive symptoms, such as feelings of guilt, "Gefühl der Gefühllosigkeit)' and a circadian pattern of symptom severity were rarely reported. Kanner et al. (2000) showed that 71% of patients with refractory epilepsy and depressive episodes, severe enough to need a psychopharmacologi-cal treatment, failed to meet criteria for any DSM-IV axis I diagnosis. A study of 199 consecutive patients with epilepsy revealed that 64% failed to meet any DSM-IV criteria using two structured clinical interviews, namely the Structured Clinical Interview for DSM-IV Axis I (SCID-I) and the Mini International Neuropsychiatric Interview (MINI) (Kanner et al., 2004).
In contrast, a recent paper by Jones et al. (2005a) showed that a current diagnosis of any mood disorder could be allocated in 24% of patients recruited in five tertiary referral centers for epilepsy in United States, using the MINI. A lifetime diagnosis of major depressive episode was reported in 17.2% of cases, 4% for dysthymic disorder and 2.8% for bipolar disorder. This study, although in line with previous authors, clearly suggests that it is possible to apply standardized criteria of DSM in a not negligible proportion of patients.
Among different potential causes for the atypical features of affective disorders in epilepsy, the peri-ictal cluster of symptoms, to some degree, may account for their features (see Chapter 15) but the possibility that the mood disorders of epilepsy may have unique characteristics has plausibility.
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