SIR: We read with interest an article prepared by Alper et al. reporting the premorbid psychiatric risk factors for postictal psychosis (PIP) following video-electroencephalographic telemetry (VEEG). Their data revealed that the only psychiatric risk factor is a high prevalence of mood disorder among the first- and second-degree relatives (44.8%, P=0.0007). Other psychiatric risk factors were not associated with the appearance of PIP during VEEG recording.⁺¹ As discussed in their manuscript, some consistency in prevalence of family history was identified in psychiatric patients. However, the finding of mood disorder was unexpected. A possible explanation suggested by the authors was related to an abnormality of modulation of excitatory neurotransmitter, in turn related to a greater tendency toward epileptic seizure clustering or multiple seizure foci that could facilitate or permit the development of psychosis. Therefore, it would be interesting to know the relationship between seizure cluster characteristics, presence of mood disorder among first- or second-degree relatives, and PIP.

We have shown regional hyperperfusion in patients with PIP, which supports an organic theory of PIP.⁺² However, there was a dispute about the underlying mechanism of PIP between focal cerebral hypofunction and hyperfunction.⁺³ Alper et al. suggested that reduced activity of inhibitory neuromodulator serotonin (5-HT) in depression, low gamma-aminobutyric acid (GABA) and GABA-synthesizing enzyme in depression, and low plasma GABA level as a trait marker in some depression patients independent of mood state may be related to their observation. Further in vivo examination of regional neurotransmitter abnormalities may unravel the underlying pathogenesis of PIP.