May 4, 2001 UNT Inhouse publication: UNT researcher to conduct time-of-day testing in schizophrenia patients

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UNT researcher to conduct time-of-day testing in schizophrenia patients

It's not uncommon to see high school students appearing sleepy and distracted during their early morning classes, and researchers have proven that they aren't just being lazy.

Teen-agers and young adults tend to be the most alert and have their best work performances in the afternoon, since their changes in body temperature, hormones and other functions related to circadian rhythms contribute to morning sleepiness, says Craig Neumann, assistant professor of psychology. Senior citizens, however, are most alert and have peak performances in the morning, he says.

Neumann says understanding the "time-of-day" effect on performances caused by circadian rhythms could be particularly helpful in the treatment of patients with schizophrenia, who tend to have attention deficits with and without medication and who have cognitive defects that cannot be fully explained by their other symptoms. He recently received a $60,000 Young Investigator Award from the National Alliance for Research on Schizophrenia and Depression to conduct time-of-day tests on 50 patients at the Dallas Veterans Affairs hospital.

Neumann was one of 157 researchers in the nation selected for Young Investigators grants. Other recipients came from Harvard, Columbia, Emory and other well-known research universities.

"Individuals with a diagnosis of schizophrenia can live on their own and function in their communities if they take medication and receive therapy," Neumann says. "Time-of-day testing focuses on both visual and verbal memory. If a patient with schizophrenia seems to test better in visual than verbal memory overall, and if he or she tests better in visual during the afternoon than in the morning, therapists may want to consider therapy that is more visually based, and schedule therapy for the afternoon."

Neumann previously conducted visual and verbal time-of-day tests on 14 patients and compared them to 14 undergraduate college students' performances on the same tests. The study was published last year in Schizophrenia Research.

In the verbal memory tests, the subjects listened to a passage from a book and were asked to summarize it immediately after hearing it and again 30 minutes after hearing it. In the visual memory tests, the subjects recalled designs shown to them immediately after they viewed the designs and again 30 minutes later.

Each person was given all tests in the morning or afternoon, then returned a week later to do the same tests at a different time of day. Neumann says allowing a week between tests attempted to counteract a practice effect — those being tested scoring better because they had just taken the same tests a few hours earlier.

The college students, all males with a mean age of 21, performed the best on both visual and verbal memory tests given during the afternoon, and performed better overall on the visual tests than the verbal tests. Their lowest scores were on verbal tests given during the morning.

The patients with schizophrenia, who were 27 years old or younger, performed much worse on both the visual and verbal memory tests as compared to the college students.

However, like the college students, they performed the best on afternoon visual and verbal memory tests and better overall on the visual tests. Their lowest scores were also on verbal tests given during the morning.

Unlike the college students, however, the patients did not show significant improvements on verbal memory tests given in the afternoon compared to the same tests given during the morning, Neumann says.

"The left side of the brain is associated with verbal memory, while the right side is associated with visual memory," he says. "The results suggest that cognitive functions associated with left-hemisphere brain functioning may be relatively more impaired in those with schizophrenia than functions associated with right-hemisphere functioning."