Weather conditions and transient global amnesia. A six-year study.

Objectives: The aetiology of transient global amnesia (TGA) is still unknown. Various events or activities have been shown to trigger TGA. A common feature of these events is an increased sympathetic activity which in turn may be influenced by meteorological factors. This prompted us to evaluate the influence of climatic parameters, and their variation on the incidence of TGA.

Methods: A total of 223 cases of TGA admitted to our hospital over a six-year period were studied. The study consisted of a comparison between the climatic parameters of days with TGA and those without TGA. The meteorological database included daily values of parameters recorded at the meteorological station of the town during this period.

Results: The onset of TGA was significantly correlated with lower daily,monthly and seasonal temperature values. Most cases of TGA were found when the temperature was less than 6.9 degrees C,whereas the frequency of TGA was minimum when it was more than 24 degrees C (P < 0.0001). Only temperature had a significant independent effect: an increase of 1 sd = 8.4 degrees C decreases the TGA admission odds of 0.78 (95 % CI: 0.62 to 0.97), i.e -22% (95 % CI: -38% to -3 %).

Conclusions: This study suggests an association between TGA occurrence and low ambient temperature. Multicentre studies taking into account climatic differences between countries are necessary to confirm our findings.