Ji. Tracy et al., A COMPARISON OF READING AND DEMOGRAPHIC-BASED ESTIMATES OF PREMORBID INTELLIGENCE IN SCHIZOPHRENIA, Schizophrenia research, 22(2), 1996, pp. 103-109
Estimating premorbid intelligence in schizophrenia is difficult becaus
e the illness affects aspects of premorbid and postmorbid functioning.
We evaluated two qualitatively different estimates of premorbid intel
ligence in a sample of schizophrenia patients and tested whether: (1)
the two indices were related and produced similar IQ estimates, and (2
) either index was related to a measure of cognitive deterioration. Th
e Barona Index (BI, a demographically-based instrument) and the Nation
al Adult Reading Test (NART, a reading test of irregularly-spelled wor
ds) were utilized. Subjects (n=40) were adult neuroleptic-medicated in
patients with a DSM-III-R diagnosis of chronic schizophrenia (n=35) or
schizoaffective disorder (n=5). Paired t-tests revealed statistically
equivalent BI and NART estimates for Full Scale and Verbal IQs, but s
ignificantly higher NART Performance IQs (t[35]= -3.34, p<0.01). Corre
lational analyses suggested the two indices were associated but shared
modest variance. BI correlations revealed expected associations with
education and social position. NART IQs were related to education and
a measure of cognitive status. Regression analyses supported the assoc
iation between NART estimates and cognitive deterioration. Results sug
gest BI may be a better estimate of premorbid intelligence in schizoph
renia as it is less influenced by potential consequences of the diseas
e.