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Year : 2017  |  Volume : 1  |  Issue : 2  |  Page : 97-101

A study on interictal depressive symptoms and laterality in temporal lobe and generalized epilepsies

1 Department of Psychiatry, Seth GSMC and KEM Hospital, Acharya Dhonde Marg, Mumbai, Maharashtra, India
2 Department of Psychiatry, University at Buffalo, The State University of New York, New York, USA

Date of Web Publication8-Dec-2017

Correspondence Address:
Neena S Sawant
Department of Psychiatry, Seth GSMC and KEM Hospital, Acharya Dhonde Marg, Parel, Mumbai - 400 012, Maharashtra
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/aip.aip_21_17

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Background: Mood disorders like inter-ictal depressive symptoms and inter-ictal major depressive episodes are the most frequent psychiatric co-morbidity seen in temporal lobe epilepsies with left hippocampal sclerosis than generalized epilepsies. Despite the clinical significance of depression, it often goes unrecognized and hence untreated in this population. These patients may tend to minimize their complaints to avoid further stigmatization of their illness. This study was undertaken to the prevalence and severity of depressive symptoms in patients with complex partial and generalized seizures, association of depression with the duration of illness and correlation of depression with right or left sided focus in complex partial seizures. Methods: 30 patients each of complex partial and generalized seizure disorder were enrolled to study depressive symptoms with the help of the Beck's Depression inventory a 21 item measure of depressive symptoms. A proforma was prepared to study the various demographic variables, details of seizure disorder &MRI findings. Results: As per the Beck's Depression inventory 26% of complex partial seizure patients and 40% of generalized seizure disorder patients had depressive symptoms which was not statistically significant. 20% and 63% of complex partial seizure patients and 30% and 40% of generalized seizure patients had moderate and mild severity of depression respectively. No significant association between left sided temporal lobe scleroses for depressive symptoms was seen. No correlation was seen of duration of illness with depressive symptoms in both the groups. Conclusions: A high prevalence of depressive symptoms in the generalized seizure group as compared to complex partial seizure group patients emphasizes the fact that the psychiatric morbidity is multi-factorial involving neurobiological as well as psychosocial issues which need to be addressed.

Keywords: Complex partial seizures, depressive symptoms, generalized seizures, laterality of seizures, mesial temporal sclerosis, temporal lobe seizures

How to cite this article:
Sawant NS, Ghosh BM. A study on interictal depressive symptoms and laterality in temporal lobe and generalized epilepsies. Ann Indian Psychiatry 2017;1:97-101

How to cite this URL:
Sawant NS, Ghosh BM. A study on interictal depressive symptoms and laterality in temporal lobe and generalized epilepsies. Ann Indian Psychiatry [serial online] 2017 [cited 2023 Mar 30];1:97-101. Available from: https://www.anip.co.in/text.asp?2017/1/2/97/220242

  Introduction Top

Mood disorders are the most frequent psychiatric comorbidity seen in patients with epilepsy(PWE),[1],[2] especially temporal lobe epilepsy(TLE),[3] particularly in those with left TLE [2],[4] and possibly hippocampal sclerosis.[5] In fact, interictal depressive symptoms, and interictal major depressive episodes, though common in epilepsy, are particularly linked to TLE,[6] than generalized epilepsies.[7]

Kanner in his review reported the prevalence of depression by several researchers to be between 20% and 55% in patients with recurrent seizures and 3% and 9% in patients with controlled epilepsy.[8] The clinical presentations of depressive disorders in epilepsy were found to be identical to those in nonepileptic patients and include major depression, bipolar and dysthymic disorders, and minor depression.[9] Kanner also suggested that the relationship between epilepsy and depression is “bidirectional” with the presence of a common pathogenic process facilitating the occurrence of one disease in the presence of the other.[10] PWE express a certain constellation of symptoms, including an explosive or irritable mood, somatic pains, anxiety and fear, and periods of brief euphoria with depressive disorders being the most common type of psychiatric comorbidity in PWE.[11]

Furthermore, PWE with depression often report a poorer quality of life on global assessments.[12] They are also at an increased risk of suicide at least five times higher and up to 25times higher in patients with partial seizures of temporal lobe origin than expected in the overall population.[13],[14] Despite the clinical significance of depression, it often goes unrecognized and hence untreated in this population. These patients may tend to minimize their complaints to avoid further stigmatization of their illness. They often present with atypical features of depression.

In general terms, it is reasonable to hypothesize that PWE can experience forms of mood disorders identical to those of patients without epilepsy. Nevertheless, it is equally reasonable to assume that the underlying brain pathology can influence the expression of psychiatric symptoms, making some aspects less evident or emphasizing others.[15]

The physician may fear that antidepressant medication may lower the seizure threshold and worsen seizure control. Robertson etal.[2] suggested that depression in PWE represents the outcome of multiple factors in individuals genetically predisposed to a primary or idiopathic affective disorder. Mendez et al.[1] proposed a specific epileptic psychosyndrome producing an atypical, endogenous depression, due to a left limbic dysfunction. This link between these two disorders has been a source of great interest to both neurologists and psychiatrists for many years and has generated an expansion of knowledge in both fields to understand the relationship of mood, cognition, and temporo-limbic function in epilepsy.

Interictal depression in PWE most commonly presents as a chronic depression that more often than not tends to mimic a dysthymic disorder with endogenous features and has an intermittent course.[8]

Therefore, in this study, we sought to investigate the prevalence and severity of depressive symptoms in patients with complex partial seizures(CPS) and generalized seizures, association of depression with the duration of illness, and correlation of depression with right-or left-sided focus in CPS.

  Methods Top

The study was conducted in the outpatient department(OPD) of psychiatry and neurology of a general hospital after obtaining Institutional Ethics Committee approval in accordance with the Declaration of Helsinki and a valid written informed consent. Patients attending the specialized epilepsy OPD of neurology and diagnosed by a neurologist as having CPS or generalized seizures based on the International League Against Epilepsy classification of seizure disorders [16] and having a brain magnetic resonance imaging(MRI) were considered for the study. Among these, patients fulfilling inclusion and exclusion criteria were enrolled in the study. The inclusion criteria were:(1) Patients of either sex and above 18years suffering from only CPS or generalized seizure disorder diagnosed by a neurologist,(2) No history of any prior psychiatric illness. Patients having any other seizure semiology or those already on psychiatric medication were excluded from the study.

Eighty-six patients were screened and sixty patients who satisfied the inclusion and exclusion criteria were enrolled in the two groups of the study.

  • GroupA: Patients having CPSs(n=30)
  • GroupB: Patients having generalized seizures(n=30).

A semi-structured proforma recorded the demographic variables, and details of seizure disorder, MRI findings, and the depressive symptoms were assessed with the help of a clinical interview and the following scales.

Beck's Depression Inventory

This scale was devised by Beck in 1961. It contains 21 sentence groups aimed at assessing the level of depression. Observed depression signs are evaluated objectively. The 21 signs of depression included in the scale are sensibility, pessimism, sense of failure, sense of guilt, self-dissatisfaction, self-accusation, desire to commit suicide, hysterical weeping, seizures, nervous breakdown, social retreat, indecisiveness, conflicting self-image, sleep disturbances, tiredness, loss of appetite, loss of weight, psychological complaints, and lack of sexual desire. All the questions were developed based on signs normally seen in depressed individuals. Each category receives a score of 0–3 points. If a patient scores 0–16 points, there is no depression, 17–20 points indicate mild depression, 21–30 moderate depression, and>31 points reveal severe depression. Studies using the scale indicate that the Beck's Depression Inventory(BDI) is an appropriate method for assessing the signs and levels of depression in a given individual.[17],[18]

BDI translation and validation in Hindi and Marathi were done by an expert committee comprising a local language translator, a professor of psychiatry, and a professor of community medicine. However, these results were not published.

All analyses were done with SPSS statistical version17 at 5% significance.

Statistical analysis

Group differences were analyzed using frequency distribution, Chi-square test, and t-test wherever applicable. Chi-square test was used to find the association between depressive symptoms and duration of illness in both the groups as well as lateralization in patients with CPS. Two-tailed “P” values were obtained for all analyses. P < 0.05 was considered statistically significant indicating 95% confidence limits.

  Results Top

Demographic and illness variables

The mean age for patients with CPS was found to be 32±7.9 and 32.9±11.8years for generalized seizure disorder. Amale preponderance was seen in both the groups with the male:female ratio being 5:1 in CPS group with 83%(n=25) being males and 16%(n=5) females and 3:2 in the generalized seizure group with 60%(n=18) of males and 40%(n=12) of females. The mean duration of illness was found to be 22.8±5.6years in CPS and 9.9±7.5years in generalized seizure disorder group which was highly significant with P <0.0001. The mean age of onset of seizures was 16.70±4.82years in CPS and 19.66±2.67years in generalized seizure disorder group which was highly statistically significant with P <0.0046. About 90% of patients in both the groups were Hindus and belonged to lower economic strata.

Prevalence and severity of depressive symptoms as per Beck's Depression Inventory

When both the groups were assessed for the prevalence of depressive symptoms as per the BDI, 26% of patients having CPS and 40% of patients having generalized seizure disorder had depressive symptoms. This difference was not statistically significant when comparing patients of both the groups[Table1a] and [Table1b].
Table 1a: Prevalence of depression on Beck's Depression Inventory (n=30)

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Table 1b: Comparison of depression as per Beck's Depression Inventory in both groups (n=30)

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Severity of symptoms as per the scores on BDI revealed 20% of CPS patients and 30% of generalized seizure patients to have moderate severity of depression. Severe depression was seen in only one patient of the CPS group. Surprisingly, extreme depression was not at all seen in both the groups. It was also seen that, though nearly 63% of CPS patients and 40% of generalized seizure patients experienced mild mood disturbances, it did not qualify for a diagnosis of depression. Borderline clinical depression was seen in one and three patients of both the groups, respectively[Table1c].
Table 1c: Severity of depression as per Beck's Depression Inventory (n=30)

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Depressive symptoms and lateralization in complex partial seizures group

All the patients were reviewed for their MRI findings. In the CPS group, 11patients had MRI findings of right mesial temporal sclerosis(MTS), 17patients had left MTS, and 2patients had normal MRI scans, whereas in the generalized seizure group, MRI findings were normal in 28patients except for 2patients of which 1 had encephalomalacia and the other had mild generalized cortical atrophy. Though 12patients(40%) of the generalized seizure group had depression, their MRI scans were normal.

While comparing the CPS group having rightand left-sided lesions for differences in depressive symptoms, no significant differences on the total BDI scores were seen[Table2].
Table 2: Comparison of depressive symptoms with magnetic resonance imaging findings in complex partial seizure group (n=28)

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Correlation of depressive symptoms with duration of epilepsy

When both the groups were compared for correlation of duration of illness with depressive symptoms as per the total BDI scores, no significant association between the two were seen in both the groups[Table3].
Table 3: Pearson's correlation of depressive symptoms with duration of epilepsy (n=30)

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  Discussion Top

Demographic and illness variables

The onset of seizures in both the groups was in their childhood or adolescence, which is keeping in with the general epidemiological findings of seizure disorders.[19] Researchers have found a longer duration of illness in focal refractory epilepsies, especially temporal lobe seizures which was also seen in our patients.[20],[21] Poor reporting, cultural factors, stigma, and myths could be responsible for the longer duration of illness where medical help seeking is done late in much of rural India. We found a male predominance in both the groups which is in keeping with other studies from India.[22]

Prevalence and severity of depressive symptoms as per Beck's Depression Inventory

In our sample of PWE, we did not find any statistical significance in the prevalence or severity of depression. However, in the generalized seizure group, the prevalence of depressive symptoms was higher than the CPS group with more patients having moderate symptoms of depression. On the contrary, many patients in the CPS group experienced mood symptoms which, however, did not qualify for diagnosis of clinical depression. Though we had not used any diagnostic criteria for the type and severity of depression, we found the prevalence of depression as per total BDI score to be 26% for CPS and 40% for generalized seizure. Our results for the CPS group happen to be slightly lower as compared to other studies where researchers have found the prevalence of mood disorders in refractory TLE to be in the range of 32.6%[23] and 30%, respectively.[24] Ertekin et al.[25] found depressive disorders in nine patients of CPS and seven patients of generalized seizures though there were no significant differences between the groups with respect to BDI scores, although depressive disorders as per the Diagnostic and Statistical Manual–IV(DSMIV)(Major Depressive Disorder, Dysthymic Disorder, and Depressive Disorder Not Otherwise Specified) were slightly more frequent in patients with TLE than in patients with idiopathic generalized epilepsy which is contrary to our findings.

Hermann et al.[26] in their review of published data using DSM-IV and International Classification of Disease nosology for rates of mood disorders in PWE found that the lifetime prevalence of mood disorders ranged from 44% to 63% of patients with the lifetime prevalence of major depressive disorder being 8%–48% with a mean of 29% and a median of 32%. Wiegartz et al.[27] evaluated 76 epilepsy patients with partial seizure disorders using the Mood Disorder section of the Structured Clinical Interview for DSM-IV(SCID-IV) and found that about 30% of their patients met criteria for a current or lifetime-to-date major depressive disorder, with 25% reporting symptoms associated with an adjustment disorder with depressed mood, dysthymic disorders, or depressive disorder not otherwise specified. Kanner had reported dysthymia to be the most common disorder in comorbidity with epilepsy [10] and that the clinical presentation of depressive disorders in epilepsy was identical to that of patients without epilepsy; interictal depression being the most common type of recognized mood disorder, which could present as major depression, minor depression, dysthymic disorder, and bipolar disorder. Quiske et al.[5] in their study using BDI found significant differences in mean BDI scores for patients with MTS and temporal neocortical lesion, with MTS patients being more prone to depression.

Hence, though researchers have found a high prevalence of depression in epilepsy, it is difficult to say which is the cause or effect. Some hypotheses have been put forth for understanding the operant pathogenic mechanisms. The pathogenic mechanisms of depression are due to the decreased serotonergic, noradrenergic functions which have been the bases for antidepressant pharmacologic treatments.[28] By the same way, a decreased activity of these same neurotransmitters has been shown to facilitate the kindling process of seizure foci, to exacerbate seizure severity, and to intensify seizure predisposition in some animal models of epilepsy.[29] Hence, parallel changes of serotonin(5-HT) and noradrenaline(NE) might be responsible for the pathophysiology of depressive disorders and epilepsy.

Depressive symptoms and lateralization in complex partial seizures

We did not find any association of laterality with the depressive symptoms in our patients with CPSs. Several researchers have given different findings. Kanner [30] and Sawant and Wankhede [31] did not find any relation between focus laterality and depression development, whereas Schmitz [32],[33] reported that depression in epilepsy occurred more frequently in patients with left temporal foci. Flor-Henry [34] was the first who showed the more frequent occurrence of depressive disorder in the right focus. Kalinin and Polyanskiy [35] in their study found that organic affective disorder was observed more frequently in patients with right-sided foci, while diagnosis of organic anxiety disorder was seen in patients with left-sided foci.

Correlation of depressive symptoms with duration of epilepsy

We did not find any correlation of depressive symptoms with the duration of epilepsy in both the groups keeping in with the findings of Indaco et al.[36] However, Swinkels etal.[37] concluded that the chronicity of epilepsy was important in the predisposition to psychiatric comorbidity, but brain dysfunction due to the involvement of the limbic system was an additional risk. Ertekin et al.[25] also postulated that the lack of a significant association with age at onset of epilepsy and duration of epilepsy suggests that the biological theories of anatomical connections were probably more important than the chronicity of epilepsy.

  Conclusions Top

We found a high prevalence of depressive symptoms in the generalized seizure group as compared to CPS group patients which has not been reported earlier. This emphasizes the fact that the psychiatric morbidity is multifactorial involving neurobiological as well as psychosocial issues which need to be addressed.

Our study has several limitations. The sample size was small and reflected a selection bias of the patient group seen at a tertiary care hospital. Though the patients were assessed by psychiatrists, we did not use diagnostic criteria for the detection of depression in the patients. Studies using SCI to establish psychiatric diagnoses and structured detailed evaluation of cases of epilepsy will definitely help in understanding the associations of epilepsy with psychiatric comorbid disorders.


We would like to acknowledge Dr.Sangeeta Ravat, Professor and Head,Department ofNeurology, Seth GSMC and KEMH, Mumbai, for giving us the guidance, support, and permission to conduct the study.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

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  [Table1a], [Table1b], [Table1c], [Table2], [Table3]


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