Yes, it is true.
According to medical statistics, there is an increase in the number of patients seeking help from psychiatric dispensaries and being hospitalized in severe condition during the spring and autumn periods. This is especially true for individuals with manic-depressive psychosis, schizophrenia, and various disorders manifesting as depression.
The reasons for this phenomenon are not entirely clear. It is suggested that exacerbations may be related to weather variability or more abrupt changes in daylight duration.