0
Get Alert
Please Wait... Processing your request... Please Wait.
You must sign in to sign-up for alerts.

Please confirm that your email address is correct, so you can successfully receive this alert.

1
Letter to the Editor   |    
Dr. Suvisaari and Colleagues Reply
JAANA M. SUVISAARI, M.D., PH.D.; JARI K. HAUKKA, PH.D.; JOUKO K. LÖNNQVIST, M.D., PH.D.
Am J Psychiatry 2002;159:500-500. doi:10.1176/appi.ajp.159.3.500

To the Editor: Drs. Fritzsche and Schmidli misunderstand our article in that we did not suggest that procreation in the summertime represents a constant hazard for schizophrenia. We observed that both patients with schizophrenia and their unaffected siblings are more often born during the winter and spring months, suggesting that among parents of patients with schizophrenia, there is a tendency to have children more often during the winter and spring. This tendency may not be related to the offspring’s risk of developing schizophrenia at all. It is also difficult to believe that there would be a link between a tendency of parents to have children during winter and spring and tick-borne infections.

However, we also observed that between 1955 and 1959 there was a pronounced seasonal variation in births of schizophrenia patients but not their normal siblings. On the basis of these findings, we suggested that the seasonal variation in schizophrenia births may consist of two components: a constant component caused by parental procreational habits and an irregular component caused by environmental risk factors that, when they occur, considerably increase the magnitude of the seasonal variation in births among patients but not their siblings and are genuine risk factors for schizophrenia. Infections caused by B. burgdorferi are one possible explanation for this irregular component. However, in Finland, Lyme borreliosis is endemic in southwestern coastal areas, in which the incidence of schizophrenia is lowest. In many northeastern areas, in which the incidence of schizophrenia is exceptionally high, ticks no longer survive (13).

Finally, we wish to point out that we do not share the belief that the incidence of schizophrenia is constant worldwide. In our other studies, we have shown that there is considerable temporal (4) and regional (3) variation in the incidence of schizophrenia in Finland, and we have also investigated time trends in the seasonal variation in births of individuals with schizophrenia (5). We have no reason to believe that this temporal and regional variation in the incidence of schizophrenia would be limited to Finland.

Reprints are not available; however, Letters to the Editor can be downloaded at http://ajp.psychiatryonline.org.

Wahlberg P, Granlund H, Nyman D, Panelius J, Seppälä I: Late Lyme borreliosis: epidemiology, diagnosis and clinical features. Ann Med  1993; 25:349-352
[PubMed]
[CrossRef]
 
Wahlberg P: [Lyme borreliosis yesterday, today and tomorrow.] Duodecim  1995; 111:1298-1303(Finnish)
[PubMed]
 
Haukka J, Suvisaari J, Varilo T, Lönnqvist J: Regional variation in the incidence of schizophrenia in Finland: a study of birth cohorts born from 1950 to 1969. Psychol Med  2001; 31:1045-1053
[PubMed]
 
Suvisaari JM, Haukka JK, Tanskanen AJ, Lönnqvist JK: Decline in the incidence of schizophrenia in Finnish cohorts born from 1954 to 1965. Arch Gen Psychiatry  1999; 56:733-740
[PubMed]
[CrossRef]
 
Suvisaari JM, Haukka JK, Tanskanen AJ, Lönnqvist JK: Decreasing seasonal variation of births in schizophrenia. Psychol Med  2000; 30:315-324
[PubMed]
[CrossRef]
 
+

References

Wahlberg P, Granlund H, Nyman D, Panelius J, Seppälä I: Late Lyme borreliosis: epidemiology, diagnosis and clinical features. Ann Med  1993; 25:349-352
[PubMed]
[CrossRef]
 
Wahlberg P: [Lyme borreliosis yesterday, today and tomorrow.] Duodecim  1995; 111:1298-1303(Finnish)
[PubMed]
 
Haukka J, Suvisaari J, Varilo T, Lönnqvist J: Regional variation in the incidence of schizophrenia in Finland: a study of birth cohorts born from 1950 to 1969. Psychol Med  2001; 31:1045-1053
[PubMed]
 
Suvisaari JM, Haukka JK, Tanskanen AJ, Lönnqvist JK: Decline in the incidence of schizophrenia in Finnish cohorts born from 1954 to 1965. Arch Gen Psychiatry  1999; 56:733-740
[PubMed]
[CrossRef]
 
Suvisaari JM, Haukka JK, Tanskanen AJ, Lönnqvist JK: Decreasing seasonal variation of births in schizophrenia. Psychol Med  2000; 30:315-324
[PubMed]
[CrossRef]
 
+
+

CME Activity

There is currently no quiz available for this resource. Please click here to go to the CME page to find another.
Submit a Comments
Please read the other comments before you post yours. Contributors must reveal any conflict of interest.
Comments are moderated and will appear on the site at the discertion of APA editorial staff.

* = Required Field
(if multiple authors, separate names by comma)
Example: John Doe



Related Content
Books
Dulcan's Textbook of Child and Adolescent Psychiatry > Chapter 9.  >
Gabbard's Treatments of Psychiatric Disorders, 4th Edition > Chapter 50.  >
Dulcan's Textbook of Child and Adolescent Psychiatry > Chapter 9.  >
The American Psychiatric Publishing Textbook of Psychopharmacology, 4th Edition > Chapter 67.  >
Dulcan's Textbook of Child and Adolescent Psychiatry > Chapter 45.  >
Topic Collections
Psychiatric News
APA Guidelines