The who, what, when and why of cognitive difficulties in epilepsy

Using the hospital anxiety and depression scale in people with epilepsy: Is overlapping symptomatology a problem?

The Hospital Anxiety and Depression Scale (HADS) is designed to screen for anxiety and depression in clinical settings. However, some items on the HADS may reflect symptoms associated with epilepsy and antiseizure medications rather than anxiety and depression. This study examined whether these items on the HADS contributed disproportionately to the reporting of anxiety and depression on the HADS in people with epilepsy (PWE). As part of a routine clinical assessment, 546 adults with epilepsy completed the HADS. In our sample, 56.2% reported elevated levels of anxiety, and 27.3% reported symptoms of depression with a score of 8 or more on the respective subscales. Scores on the anxiety and depression subscales were not associated with age, sex or epilepsy type. We did not find a relationship between endorsement of items related to panic, feelings of dread or butterflies in the stomach and a diagnosis of temporal lobe epilepsy. The most frequently endorsed item on the anxiety subscale of the HADS in the sample as a whole related to worrying thoughts, rather than the more somatic manifestations of anxiety. The item 'I feel as if I am slowed down' was endorsed by the majority of people with epilepsy and may not reflect a symptom of depression in this group. Careful analyses of the pattern of endorsement of specific items on the HADS may improve the sensitivity of this screening measure to the presence of depression in people with epilepsy.

The impact of recreational cannabis use on neuropsychological function in epilepsy

Cannabis use is associated with neuropsychological impairments in the general population, but little is known about the impact on cognitive function in people with epilepsy who are already at increased risk of difficulties due to the essential comorbidities of the disease. We compared the performance of 42 people with epilepsy (PWE) who reported regular cannabis use with 254 age matched, non-cannabis-using PWE. Patients completed tests of intellectual reserve, memory, language and processing speed. Approximately one in 17 patients (5.9 %) reported current cannabis use. Cannabis use was not associated with epilepsy type. Males were 1.8 times more likely to report cannabis use compared to females. Cannabis use was associated with lower intellectual reserve (Reading IQ: t = 2.8, p < 0.01, Cohen's d = 0.49), reduced encoding of new information (List Learning: t = 3.3, p < 0.001, Cohen's d = 0.56) and enhanced susceptibility to distraction on a subsequent recall task (t = 3.07, p < 0.01, Cohen's d = 0.51. In regression models cannabis use was significantly associated with impairments in learning and recall after controlling for elevated levels of anxiety and depression. Our data indicates that recreational cannabis use in people with epilepsy amplifies deficits in new learning and enhances susceptibility to distraction in the retention of newly learnt material. Recreational cannabis use should be considered when interpreting the significance of these cognitive impairments when they are recorded in a clinical assessment.

What are we really predicting with fMRI in epilepsy surgery?

While memory and language functional magnetic resonance imaging (fMRI) paradigms are becoming evermore refined, the measures of outcome they predict following epilepsy surgery tend to remain single scores on pencil and paper tests that were developed decades ago and have been repeatedly shown to bear little relation to patients' subjective reports of memory problems in the real world. The growing imbalance between the increasing sophistication of the predictive paradigms on the one hand and the vintage measures of the outcome on the other in the fMRI epilepsy surgery literature threatens the clinical relevance of studies employing these technologies. This paper examines some of the core principles of assessing neuropsychological outcomes following epilepsy surgery and explores how these may be adapted and applied in fMRI study designs to maximize the clinical relevance of these studies.