The National Schizophrenia Foundation (NSF) is a non-profit organisation founded in 1950 which declared May 24 as World Schizophrenia Day in honor of Dr. Philippe Pinel. Dr. Pinel (1745 – 1826) was a french physician who pioneered in treatment and healthcare of the mentally diseased. Contrary to the prevailing opinion and usual treatment methods, he considered social and psychological stress and mental illness and considered hereditary and physiological factors in his publication Nosographie philosophique (“Philosophical Classification of Diseases”). He recognized different psychoses and distinguished symptoms like hallucination and withdrawal.
Each year from 20 to 27 May Schizophrenia Awareness Week (SAW) has been celebrated since 1986 worldwide. SAW takes place in order to help schizophrenia patients and increase sensitivity and raise awareness towards the disease, it’s symptoms and to erase prejudices.
Schizophrenia is affecting about 22 million people worldwide according to the World Health Organization (WHO). Schizophrenia is a chronic mental disorder which manifests itself through various symptoms. There are so-called negative symptoms like deficits in attention, executive functions and working memory and positive symptoms such as hallucinations and delusions (ct. Patel et al., 2014).
Pathophysiological theories of schizophrenia are based on abnormalities in neurotransmission. There is either an excess or a deficiency of neurotransmitters such as dopamine or gamma-aminobutyric acid (GABA) (cf Schwartz & Javitch, 2013).
There are four dopaminergic pathways which are believed to be affected: The nigrostriatal pathway, which runs through the substantia nigra and the caudate nucleus. Low dopamine levels within the nigrostriatal pathway lead to motor symptoms. An excess of dopamine in the mesolimbic pathway, starting at the ventral tegmental area (VTA) and ending in the limbic areas, may result in positive symptoms of schizophrenia (ct. Patel et al., 2014). Negative symptoms may be caused by low dopamine levels in the mesocortical pathway, which goes through the VTA and ends in the cortex. A lower level of dopamine in the tuberoinfundibular pathway which proceeds through the hypothalamus to the pituitary gland leads to e.g. amenorrhea* (ct. Patel et al., 2014).
For Schizophrenia there is evidence for a semantic memory and a specific disorder of frontal lobe function which aggravates the interpretation of poor verbal skills of patients. Testing Verbal fluency also yields insights in a patient’s executive function and semantic memory skills, there when testing verbal fluency one needs to use the Boston Naming or the Stroop tor less which are both less confounded tests to analysis the relation between verbal fluency and severity of negative symptoms of Patients. (cf. Joyce et al., 1996) Findings from other studies such as Crawford et al. 1993 also suggest that a smaller IQ is not a sufficient explanation of the associated poor verbal fluency, this means that the impairments in letter and category verbal fluency are not only due to a lower IQ.
In addition to the psychotic symptoms, which are often most salient in schizophrenia, cognitive impairment can also occur in for example the semantic memory. The impairment of verbal fluency as a symptom of a neurological disease can be found in many other diseases such as Alzheimer’s Disease (Tröger, Linz, König et al. 2019), Parkinson’s Disease or Huntington’s Disease. Due to the analysis of verbal fluency researchers gained new information about possible neural substrates mediating aspects. Findings for example indicate that category fluency is normally superior to letter fluency. (cf. Joyce et al., 1996)
If you are interested in further reading about hallucinations and voice hearing in Schizophrenia, find here another interesting article about this topic.
*lack of menstruation during fertile age