Letter

Psychiatric Effects of Heat Waves

To the Editor: Heat waves have an effect on health, sometimes lethal, which was particularly evident in Europe during the intensely hot summer of 2003 ( 1 , 2 ). Even though the incidence of deaths and illness related to heat waves is reported to be increasing, there are no specific data on the psychiatric effects of heat waves.

Studies about the psychiatric effects of weather have produced scattered results, probably because of a lack of diagnostic specificity and the complexity of analyzing weather variables. In addition, no single methodological approach has been used to examine these effects. The methods used range from self-report questionnaires to data on emergencies and hospital admissions. Published reports have dealt mainly with suicide and violent behavior related to weather ( 3 , 4 ).

In view of the substantial health impact of the 2003 European heat wave and the paucity of data on psychiatric effects, we decided to analyze psychiatric emergencies in a general hospital in Barcelona during the heat wave of 2003. The period was defined as the days with a maximum temperature of at least 32 degrees Celsius (89.6 Fahrenheit), a period that lasted for 15 days that summer. We compared data from the heat wave period with data from the other summer days in 2003, examining emergency visits; hospital admissions; clinical and sociodemographic data; scores on the Severity of Psychiatric Illness Scale (SPI) ( 5 ), which measures the severity of a disorder with predictive value for admission; the treatment rendered, including use of restraints; and referral. The study was approved by the hospital Ethics Committee.

During the heat wave period, 125 psychiatric emergencies were attended to, which accounted for 14 percent of the total psychiatric emergencies attended to during the entire summer (N=872). No differences were found in the number of emergency visits or admissions. However, during the heart wave, significantly more alcohol and sedative use disorders were reported, and patients were less likely to report anxiety disorders. Overall, individuals seen during the heat wave were more likely to report a history of psychiatric conditions and treatment and greater use of psychiatric services; they also had to be restrained more often and had higher scores on the SPI scale item measuring dangerousness toward others. In only half of these cases was the dangerousness attributed to alcohol or drug use.

The 2003 heat wave produced intense effects in many countries, and this study provides evidence of possible psychiatric repercussions, of which mental health clinicians should be aware. Clinicians and administrators should consider primary and secondary prevention approaches to address psychiatric symptoms that may result from heat waves.