Binghamton: Gregory P. Strauss and his graduate students at Binghamton University
have found surprising physiological connections to schizophrenia in
their quest to better understand the mental disorder.
Schizophrenia affects about 1 percent of the world’s population and
is the #1 cause of medical disability in the United States. The biggest
reason for this high rate of disability is severe impairment in
cognition, which makes it difficult to work or perform activities of
daily living. Unfortunately, the cause of these cognitive impairments is
poorly understood.
A recent paper by graduate student Lindsay Morra, which Strauss
supervised, found that medical conditions such as diabetes, a high
waist-to-hip ratio and especially high blood pressure were “particularly
associated with a range of cognitive deficits” that occur in
schizophrenia. This finding is significant because it suggests that
general health problems that affect the body also affect the brain and
cognition in schizophrenia. Earlier studies mostly focused on structural
or neurochemical abnormalities that affect the brain broadly. The
research from Strauss’ lab raised an important possibility that treating
metabolic abnormalities, such as hypertension, may improve cognition in
schizophrenia.
“The brain is intricately wired to receive blood from arteries,”
Strauss says. “In people with schizophrenia, who often have had high
blood pressure for 20 to 40 years, there is a systemic effect on the
brain caused by a hardening of the arteries, which affects the brain’s
ability to efficiently distribute blood throughout the brain.”
Several potential mechanisms complicate the interpretation of the
finding in Morra’s study, Strauss says. “One is actually, unfortunately,
the antipsychotic medications,” he notes. “They can cause the metabolic
abnormalities to come about.”
Most of the recent drug therapies carry risks of elevated blood
sugar, high blood pressure, weight gain and higher cholesterol. The new
study was unable to follow the participants longitudinally to determine
the cause-effect role of the antipsychotics.
All of this is not to say that high blood pressure causes
schizophrenia or vice versa. Correlation isn’t causation, as the saying
goes, and Strauss emphasizes that “metabolic abnormalities only predict a
small proportion of the cognitive impairment in schizophrenia.”
Another potential explanation for cognitive impairment, which Strauss
is investigating with a new grant from the American Psychological
Foundation, is what he calls a “motivational impairment,” or abnormal
interaction of the brain’s reward system with the prefrontal cortex that
can cause a certain kind of reward process to go haywire.
Strauss explains it like this: For years, clinicians have thought
that patients suffering from schizophrenia were cognitively impaired
because something in the brain was demotivating them. “We’ve explored
that, and we basically don’t think that that’s true,” he says. “What we
think happens is that they try adequately but they’re inefficient at
allocating their efforts.”
Healthy individuals, he says, engage in a labor-leisure tradeoff.
When it’s necessary, psychiatrically healthy individuals ramp up their
brain’s efforts when confronted with a hard task, but automatically ease
off when that task gets easier or ends. They do this unconsciously, and
it’s why you might like to play a mindless video game after a hard day
at work.
By using brain recording techniques and pupillometry — the
measurement of pupil diameter, which is a way to assess the amount of
cognitive effort that someone exerts — Strauss and his students have
found that it’s not that the brains of those suffering from
schizophrenia aren’t expending as much effort; they’re ramping up and
down their efforts inefficiently.
“They basically end up in the state of mental fatigue really quickly
because they expend their effort inefficiently, and they can’t overcome
it,” says Strauss, who received Early Career Awards for Research last
year from the National Academy of Neuropsychology and the American
Psychological Foundation.
By researching motivational mechanisms that can cause the cognitive
impairments, Strauss hopes that he and his students might be able to
design “cognitive rehabilitation training programs,” similar to some of
the online brain games you’ve probably heard of.
“What we’re working toward,” he says, “is developing new cognitive
training programs that actually target the motivational mechanisms that
are inherent to schizophrenia and cause them to become mentally fatigued
more quickly.”