Effects of climate on admission rates of schizophrenia patients to psychiatric hospitals.

Data on admissions of schizophrenia- and schizoaffective disorder patients to Tel-Aviv's seven public psychiatric hospitals during 11 consecutive years were obtained along with relevant meteorological information. Mean monthly admission rates were significantly higher during the summer (for schizophrenia patients) and fall (for schizoaffective patients). Schizophrenia patients' mean monthly admission rates correlated with mean maximal monthly environmental temperature (R = 0.

Admission rates of bipolar depressed patients increase during spring/summer and correlate with maximal environmental temperature.

Objective: We intended to identify a relationship, if exists, between various climatic factors and the admission rates of bipolar affective disorder depressed patients (BPD) or major depressive disorder patients (unipolar) (UPD) to psychiatric hospitals, as well as potential seasonal variability in hospitalization rates of this population.

Methods: Data on admissions of ICD-9 BPD and UPD patients to Tel Aviv's seven public psychiatric hospitals during 11 consecutive years were collected along with concomitant meteorological information

Results: Admissions of 4117 patients with BPD and 1036 with UPD who fulfilled our specific inclusion criteria were recorded. Bipolar depressed, but not UPD, patients exhibited significant seasonal variation (higher spring and summer versus winter mean monthly admission rates), and the admission rates of patients with BPD, but not UPD, correlated significantly with mean maximal monthly environmental temperature

Conclusions: Increased environmental temperature may be a risk factor for evolvement of major depressive episode in patients with bipolar disorder with psychiatric co-morbidity, at least in cases that necessitate hospitalization and at the examined geographic/climatic region of Israel.