Abstract
Introduction: Epilepsy is associated with adverse effects on cognition and psychological functioning. Polytherapy and poor seizure control have been associated with poor cognition. Little research has been carried out on the impact of epileptic seizures and anti-epileptic drugs (AED) on cognition in patients with brain tumours (BT). We have compared cognitive abilities in patients with tumour associated epilepsy (TAE) (“controlled” and “active”) and compared this with non-tumoural epilepsy (NTE) with active epilepsy to look at the effect of polytherapy and seizure frequency on cognition. METHODS: We studied cognition, mood and fatigue in patients with epilepsy attending the Edinburgh Centre for Neuro-Oncology clinic with TAE (n = 32 “controlled” and n = 36 “active”) and patients attending a hospital epilepsy service with NTE (n = 29). Consented patients completed the following neuro-cognitive tests (Hopkins Verbal Learning Test–Revised, Brain Injury Rehabilitation Trust - Memory and Information Processing, the Trail Making Test, the Controlled Oral Word Association Test, the Hospital Anxiety and Depression Scale (HADS) and the Brief Fatigue Inventory. Results: The two TAE groups did not significantly differ in any tumour variables (type, location, site, lateralisation, therapy). Patients with “controlled” TAE were significantly more often taking AED monotherapy compared with patients with “active” TAE and NTE. Most patients (78%) were on “new generation” AEDs. Levetiracetam was the most common prescribed drug (monotherapy and first-drug polytherapy). Patients with “controlled” TAE (M = -0.6, SD = 0.8) scored significantly higher on a composite memory (verbal and visual) z-score than those with “active” TAE (M = -1.13, SD = 1.09) and NTE (M = -1.35, SD = 0.85) [F (2,94)= 11.69, p= 0.001]. Multinomial Logistic Regression Analysis showed that even when controlled for the cognitive effect of AED polytherapy the relative risk of having memory impairment was 98% higher for patients with “active” compared to “controlled” TAE, p = .03, 95% CI [6%, 270%]) (and even higher for NTE). Furthermore NTE patients (M = 9.26, SD = 3.77) were significantly more anxious than “controlled” TAE patients (M = 6, SD = 4.91) [F (1,78)= 8.82, p= .003] as measured on the HADS (7 items scored from 0-3; caseness cut-off 8). CONCLUSION: Seizure control is associated with better cognitive memory abilities and psychological functioning in TAE patients. AED polytherapy with newer agents does not necessarily lead to an additional cognitive burden. Whereas previous studies stressed the negative influence of AED (poly-) therapy on cognition in BT patients, the present study suggested a cognitive impact of “active” TAE beyond the influence of AEDs. The prominent cognitive impact of AED therapy in previous studies may have been be related to the type of drugs prescribed, if patients were taking AEDs of the “old generation”.