isode is in the early- to mid-20s for males and in the late-20s for females. The onset may be
abrupt or insidious, but the majority of individuals manifest a slow and gradual develop-
ment of a variety of clinically significant signs and symptoms. Half  of these individuals
complain of depressive symptoms. Earlier age at onset has traditionally been seen as a pre-
dictor of worse prognosis. However, the effect of age at onset is likely related to gender,
with males having worse premorbid adjustment, lower educational achievement, more
prominent negative symptoms and cognitiv e impairment, and in general a worse out-
come. Impaired cognition is common, and altera tions in cognition are present during de-
velopment and precede the emergence of psycho sis, taking the form of stable cognitive
impairments during adulthood. Cognitive impairments may persist when other symptoms
are in remission and contribute to the disability of the disease. 
The predictors of course and outcome are la rgely unexplained, and course and outcome
may not be reliably predicted. The course appears to be favorable in about 20% of those
with schizophrenia, and a small number of indi viduals are reported to recover completely.
However, most individuals with schizophrenia still require formal or informal daily living
supports, and many remain chronically ill, with exacerbations and remissions of active
symptoms, while others have a course of progressive deterioration.
Psychotic symptoms tend to diminish over the life course, perhaps in association with
normal age-related declines in dopamine activity. Negative symptoms are more closely re-
lated to prognosis than are positive symptoms and tend to be the most persistent. Further-
more, cognitive deficits associated with the illness may not improve over the course of the
illness.
The essential features of schizophrenia are th e same in childhood, but it is more diffi-