Dynamic changes of cognitive habituation and serotonin metabolism during the migraine interval

Migraine patients show a specific cognitive processing with a loss of habit uation in the interval and a normal habituation in the attack as measured b y event-related potentials (ERPs). It is unknown whether the loss of habitu ation changes during the migraine interval or is a stable state. Serotonin (5HT) metabolism is involved In the pathophysiology of migraine and also in the generation of ERPs. We enrolled 14 patients with regular migraine atta cks in order to measure visually evoked ERTs repetitively during the migrai ne interval and in the migraine attack. Cognitive habituation was evaluated by analysis of P3 latency, platelet serotonin content and free serotonin p lasma level were measured at the same time points. The loss of habituation increased continuously during the migraine interval and abruptly normalized in the migraine attack (p < 0.05, time series analysis). The platelet 5HT content decreased significantly in the migraine attack (p < 0.03) and was a t its maximum in the middle of the interval. The P3 latency was significant ly increased in the attack (p < 0.01) and was significantly inversely corre lated with the platelet 5HT content (r = -0.44, p < 0.001). Free 5HT plasma levels did not show any significant change. Our findings suggest that loss of cognitive habituation continuously increases during the migraine interv al until its normalization in the migraine attack. This phenomenon cannot b e attributed to serotonergic transmission. In patients with regular changes of cognitive habituation before the migraine attack, it might be possible to predict the attack by analysing ERPs.