The impact of antidepressants on seizure frequency and depressive and anxiety disorders of patients with epilepsy: Is it worth investigating?

PURPOSE

Depression and anxiety disorders in patients with epilepsy (PWE) remain under-recognized and under-treated, despite being the most common psychiatric co-morbidities. Selective serotonin re-uptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs) are considered first-line treatment for primary depression and anxiety disorders. We performed this study to investigate if SSRIs and SNRIs could affect the seizure frequency of PWE and to assess whether such effect is independent of the response of the mood and anxiety disorders to these drugs.

METHODS

This was a retrospective study of 100 consecutive PWE who were started on an SSRI or SNRI for the treatment of a depressive and/or anxiety disorder. Every patient underwent a psychiatric evaluation by one of the investigators using a semi-structured interview who also managed the pharmacologic treatment in all the patients. Patients were excluded if they had a diagnosis of psychogenic non-epileptic seizures or if they had undergone epilepsy surgery or the implant of the vagal nerve stimulator six months before and after the start of the antidepressant therapy. The final analysis was conducted in 84 patients. For each type of seizure, an average and maximal monthly seizure frequency during the six months preceding and following the start of psychotropic drugs was extracted from the medical records. We identified the number of patients whose seizure frequency during treatment with antidepressants: (i) shifted from a <1/month to a ≥1 seizure/month and vice-versa, (ii) increased beyond maximal/monthly baseline frequency, and (iii) patients who developed de-novo generalized tonic-clonic (GTC) seizures.

RESULTS

None of the patients with a baseline seizure frequency <1seizure/month went on to have ≥1seizure/month after initiating treatment with antidepressants, had an increase in frequency beyond baseline maximal counts or developed de-novo-GTC seizures. Furthermore, there was no seizure recurrence among patients that had been seizure-free. Among the patients with a baseline seizure frequency ≥1/month, 27.5% had a reduction in seizure frequency to <1/month, which suggested a positive effect of SSRI/SNRI on seizure frequency (p=0.001, McNemar test). Among the patients with a baseline seizure frequency ≥1seizure/month, 48% exhibited a >50% reduction in seizure frequency after the start of treatment with SSRIs or SNRIs. A therapeutic response to SSRIs and SNRIs was found in 73% of patients. The change in seizure frequency was independent of the improvement in psychiatric symptomatology.

CONCLUSION

In this retrospective observational study, SSRIs or SNRIs did not appear to worsen seizure frequency. Also, in patients with frequent seizures, SSRIs and SNRIs may be associated with a possible decrease in seizure frequency. Furthermore, these drugs appear to yield good therapeutic response of psychiatric symptoms independently of seizure frequency. It is pivotal to replicate these data in prospective, double-blind, placebo-controlled trials.

Environmental levels of the antidepressant venlafaxine impact the metabolic capacity of rainbow trout

The antidepressant venlafaxine is detected at parts per billion levels in tertiary-treated municipal wastewater effluent. However, the impact of this serotonin-norepinephrine reuptake inhibitor (SNRI) on non-target aquatic animals is poorly understood. We tested the hypothesis that environmentally relevant levels of venlafaxine disrupt the highly conserved cortisol and glucose response to stress in rainbow trout (Oncorhynchus mykiss). Juvenile trout were exposed to venlafaxine (0, 0.2 and 1.0 μg/L) in a static system with daily renewal for seven days. The fish were then subjected to an acute handling disturbance and sampled either prior to (0 h) or 1, 4 and 24h after stressor exposure. Venlafaxine exposure did not affect the handling disturbance-mediated transient elevation in plasma cortisol levels or target tissue glucocorticoid receptor expression. The drug exposure disrupted the interrenal steroidogenic capacity, including altered handling stressor-mediated changes in mRNA abundances of steroidogenic acute regulatory protein and cytochrome P450 side chain cleavage. The handling stressor-induced transient elevations in plasma glucose levels were significantly reduced in the venlafaxine-exposed fish. This was not accompanied by changes in liver glycogen content, glucose transporter 2 mRNA abundance or the glycolytic capacity, whereas the capacity for gluconeogenesis and amino acid catabolism were enhanced. Venlafaxine also brought about changes in the gill of trout, including enhanced lactate dehydrogenase activity and Na(+)-K(+) ATPase protein expression, while the Na(+)-K(+) ATPase enzyme activity was reduced. Collectively, our results demonstrate that venlafaxine at levels detected in the aquatic environment impacts tissue metabolic capacities and may compromise the adaptive responses to an acute stressor in rainbow trout.