Schizophrenia A group of severe disorders characterized by disorganized and delusional thinking, disturbed perceptions, and inappropriate emotions and behaviours. Those with paranoid tendencies are particularly prone to delusions of persecution. Disorganized thinking may result from a breakdown in selective attention. (Reichenberg & Harvey, 2007) Hallucinations are sensory experiences without sensory stimulation, most often auditory. The expressed emotions of schizophrenia are often utterly inappropriate, split off from reality. (King & Caponigro, 2010). Other emotional breaks: flat affect; difficulty in perceiving facial emotions and reading other's states of mind. (Green & Horan, 2010).

Subtypes of Schizophrenia Memorize Table 50.1 (m659 c )for the next exam. Schizophrenia typically strikes young people maturing into adulthood (late teens and early twenties). Men tend to be struck earlier, more severely, and slightly more often. (Picchioni & Murray, 2007). Schizophrenia (Gk. for 'shattered mind *not* split personality'), is a cluster of disorders. Positive symptoms are hallucinations, disorganized speech, delusional thoughts, inappropriate emotional responses to social stimuli. Negative symptoms are toneless voices, expressionless faces, mute or rigid bodies, which equals flat affect. When schizophrenia is chronic, process, slow onset, recovery is doubtful.

Subtypes of Schizophrenia Cont'd Those with chronic schizophrenia often exhibit the incapacitating symptoms of withdrawal. (Kirkpatrick et al., 2006) Men, whose onset is 4 years earlier, more often exhibit negative symptoms and chronic schizophrenia. (Rasanen et al., 2000) Rapid or acute schizophrenia following life stresses predicts a more rapid and likely recovery. They often have more positive symptoms that respond to drug therapy. (Fowles, 1992). Might imbalances in brain chemistry underlie schizophrenia, as was the case of the 'mad hatter', British hatmakers moistened the brims of mercury-laden hats with their tongue and lips (Smith, 1983).

Brain Abnormalities Schizophrenia is likely caused by a sixfold excess of the D4 dopamine receptor. (Seeman et al., 1993) Hyper-responsive dopamine system may intensify brain signals, creating positive symptoms. (Grace, 2010). Drugs that block dopamine receptors often lessen these symptoms, drugs that increase dopamine levels, such as amphetamines and cocaine, sometimes intensify them. (Seeman 2007). Some schizophrenics have abnormally low activity in the frontal lobes (Morey et al., 2005) One study took PET (positron emission tomograph) scans of brain activity while people were hallucinating. (Silbersweig et al., 1995). When they heard a voice or sight, their brains became vigorously active in the thalamus.

Brain Abnormalities Cont'd Schizophrenics also display a noticeable decline in synchronized neural firing in the frontal lobes. (Symond et al., 2005) Out-of-sync neural firing may disrupt the integrated functioning of neural networks. Combine this with increased activity in the amygdala, and paranoia is the sure result. (Epstein et al., 1998) Sulci are enlarged, and fluid-filled, with a corresponding shrinkage of cerebral tissue. (Goldman et al., 2009) Smaller-than-normal thalamus may explain why schizophrenics have difficulty filtering sensory input and focusing attention. (Ellison-Wright et al., 2008) Risk factors include low birth weight, maternal diabetes, old paternal age, and oxygen deprivation during delivery. (King et al., 2010). Think triggers, not causes.

Maternal Virus During Midpregnancy Could an intrauterine viral infection be the cause? Pregnant during a flu epidemic? (Wright et al., 1995) If the mother had the flu during pregnancy, will their child be more at risk? Yes, but only during the second trimester. (Brown et al., 2000) Does blood drawn from pregnant women with a schizophrenic child show higher-than-normal levels of antibodies (suggesting a viral infection)? Yes. (Brown et al. 2004) Another study found traces of a specific retrovirus (HERV) in nearly half of people with schizophrenia and virtually none in healthy people. (Perron et al., 2008) Does the infection weaken glial cells, leading to reduced synaptic connections (Moises et al., 2002)

Twins and Schizophrenia Identical twins share a prenatal environment; about 2/3 share a placenta. If one has schizophrenia, the co-twin's chances are 6 in 10 if they shared a placenta. If they had separate placentas, the chances are 1 in 10. (Phelps et al., 1997) Children adopted by someone who develops schizophrenia seldom develop the disorder, instead they have an elevated risk if their biological parent has it. (Gottesman, 1991). Epigenetic factors influence gene expression: viral infections, nutritional deprivation, maternal stress. Identical twins' differing histories in the womb and beyond explain why only on of them may show differing gene expression. (Walker et al., 2010).