Weight Gain and Antipsychotic Medication: Differences Between Antipsychotic-Free and Treatment Periods
J Clin Psychiatry 2001;62:694-700
© Copyright 2014 Physicians Postgraduate Press, Inc.
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Background: We performed a retrospective
analysis of data involving 121 inpatients to examine the rate of
weight gain during antipsychotic-free periods and during
treatment with various antipsychotic drugs.
Method: Data were analyzed to determine
differences in weekly weight change during antipsychotic-free (N
= 65), typical antipsychotic (N = 51), or atypical antipsychotic
(N = 130) treatment periods. Atypical antipsychotic treatment
periods were further subdivided into olanzapine (N = 45),
clozapine (N = 47), or risperidone (N = 36) treatment periods. A
paired comparison was conducted on 65 patients who had an
antipsychotic-free treatment period preceding or following a
neuroleptic drug treatment period. In addition, patients were
classified as either non-obese (with a body mass index [BMI]
<= 29.9 kg/m2) or obese (BMI >= 30.0 kg/m2)
to test whether the rate of weight gain during treatment periods
was related to initial BMI.
Results: Across all treatment periods, weekly
weight gain was as follows: 0.89 lb/wk (0.40 kg/wk) on atypical
antipsychotic medication, 0.61 lb/wk (0.27 kg/wk) on typical
antipsychotic medication, and 0.21 lb/wk (0.09 kg/wk) on no
antipsychotic medications. The atypical antipsychotic versus
antipsychotic-free comparison was significant (F = 3.51; df =
2,231; p = .031), while the typical antipsychotic versus
antipsychotic-free comparison was not. Among the individual
atypical antipsychotic medications, significantly more weight
gain occurred during olanzapine treatment (1.70 lb/wk) (0.76
kg/wk) than with either clozapine (0.50 lb/wk) (0.22 kg/wk) or
risperidone (0.34 lb/wk) (0.15 kg/wk) treatments (F = 7.77; df =
2,117; p = .001). In the paired analysis with patients serving as
their own controls, the difference between weekly weight gain
during atypical antipsychotic treatment and antipsychotic-free
treatment was significant (t = -3.91; df = 44; p = .001), while
the difference between weight gain during typical antipsychotic
treatment and antipsychotic-free treatment was not significant.
With the individual drugs, treatment with both olanzapine and
clozapine caused significantly higher weekly weight gain than
antipsychotic-free treatment (p = .001 and p = .036,
respectively), while treatment with risperidone did not.
Non-obese patients (BMI < 29.9 kg/m2) and obese
patients (BMI > 30.0 kg/m2) did not differ
significantly in their weight gain during typical or atypical
Conclusion: Treatment with atypical
antipsychotics was associated with more weight gain than
treatment with typical antipsychotics. Among the atypical drugs,
olanzapine was associated with more weight gain than either
clozapine or risperidone. The patient's admission BMI was not
associated with the amount of weight gained during subsequent