An overview of all methods of diagnosing functional mental illnesses (schizophrenia, depression, and others) from Doctor of Medical Sciences Irina Valentinovna Shcherbakova.  

The most important stage in psychiatric care for patients is the establishment of the correct diagnosis. It is the diagnosis that determines the further strategies of patient management, treatment, prognosis and prospects.  

By the methods of diagnosis in psychiatry include:  

• clinical – conversation, observation 
• psychometric – pathopsychological research 
• laboratory – genetic, immunological (Neurotest) 
• instrumental – tomography, EEG, Neurophysiological test system (NTS) 

Clinical methods

The main methods of diagnosing mental illness remain clinical. To determine a mental disorder, the doctor uses information about the symptoms of the disease, which he receives from the patient and his loved ones during the conversation. In addition, the doctor observes the patient: his motor activity, facial expressions, emotions, speech, and the nature of his thinking. Assessment of the development and modifications of the signs of the disease gives an idea of ​​the speed of the course of the disease, its nature. An analysis of the totality of the obtained clinical data makes it possible to establish a specific mental disorder.        

Clinical methods depend on subjective factors:  

• the frankness of patients, their relatives in the presentation of the picture of the disease and the facts of the biography   
• experience and knowledge of the doctor 

The use of additional objective research methods – laboratory, instrumental – increases the reliability of the diagnosis of mental disorders and allows you to choose the optimal means of therapy.   

Most public and private psychiatric clinics are limited only to “necessary and sufficient” clinical examination methods. First of all, we are talking about the diagnosis of functional mental disorders – those that occur in the absence of brain damage. In functional disorders, X-rays or tomography do not show any abnormalities.     

By common functional disorders include: 

• endogenous psychoses, including schizophrenia, schizoaffective and delusional disorders 
• schizotypal disorder
• mood disorders (depression, mania, bipolar disorder)
• neurotic disorders

The symptoms of these diseases can be very similar to each other or “overlap”, acting as non-specific signs of mental pathology. This often occurs in the early stages of development or temporary attenuation of painful conditions. 

The distinction between an outwardly similar, but for essentially different diseases – a difficult task, which may take several months (!). To recognize a mentally ill person, it is necessary to use different diagnostic methods in combination (clinical, psychometric, laboratory and instrumental).     

It is also important to make a correct diagnosis early because, thanks to an early start of treatment, the patient goes into remission or recovers faster , and his quality of life and social prognosis improve .   

Psychometric diagnostic methods in psychiatry 

Psychometric methods provide more information about the patient ‘s current mental health status . The specialist uses standardized scales (which have passed scientific research) to assess mental disorders in points: anxiety, depression, mania, dementia. Psychometry provides the doctor with additional information about the severity of the disorder, as well as the effectiveness of treatment.      

Psychometric scales are divided into: 

• self – questionnaires – the patient fills in based on his feelings  
• questionnaires – filled in by the doctor 

More expanded and concretizing information is provided by pathopsychological examination . It is conducted by a clinical psychologist.  

To understand that a person has a mental disorder, a battery of standardized tests, tasks and scales is used as psychodiagnostic methods . They assess the main areas of the psyche:   

• thinking
• Attention
• emotions
• will
• memory
• intelligence
• personality traits of a person

During the examination, the specialist finds even the smallest changes that have not yet been determined by clinical methods. The method is most effective when a mental disorder is suspected , to clarify the diagnosis, to assess the degree of mental defect.  

Laboratory methods

Improving the efficiency of diagnostics is directly related to the development of new methods and principles for diagnosing mental disorders, which are based on objective biological criteria. The now actively being sought biological signs (markers) for schizophrenia and schizophrenia spectrum disorders: examines genetic, immunological, neuro-physiological parameters. Finding the features that are inherent in a particular disease is the basis for creating additional diagnostic tests for schizophrenia. Despite worldwide efforts, there are very few such features openly. Below we will consider the most significant of them.          

Genetic factors make an undeniable contribution to the formation of a predisposition to schizophrenia and other mental illnesses . Indeed, patients’ families often have relatives who suffer from mental disorders. The closer the degree of consanguinity , the higher the risk of getting sick. The risk is highest if both parents or the patient’s twin are ill.      

Attempts to find genes – markers of schizophrenia have led to ambiguous conclusions. It turned out that patients with schizophrenia have hundreds of gene abnormalities in various combinations. The identification of such deviations is not evidence of schizophrenia, but only indicates the likelihood of its occurrence. The development of the disease occurs when many factors (internal and external) interact , including genetic ones.          

Another direction in the search for markers of schizophrenia and schizophrenia-like disorders is immunological methods . By the end of the twentieth century, a close connection between the nervous and immune systems became apparent , special molecules and substances were discovered that are involved in this interaction.        

It turned out that some of the immune factors that circulate in the blood can respond to mental changes and reflect the disease processes that occur in the brain. Among such factors:    

• antibodies to brain proteins 
• leukocyte elastase
• alpha 1-proteinase inhibitor
• C-reactive protein

The number of antibodies to brain proteins increases markedly in some forms of schizophrenia, autism, and developmental delays. The measurement of the level of such antibodies in the blood is widely used as a method to complement clinical methods of psychiatric diagnosis. In isolation from clinical data, this method is not valid, since an increase in the level of antibodies is also observed in other diseases of the nervous system: multiple sclerosis, encephalitis, trauma, and tumors.      

A more sensitive way to diagnose mental disorders is to determine in the blood indicators of innate immunity, namely, pro-inflammatory factors: leukocyte elastase, alpha-1-proteinase inhibitor, C-reactive protein. Scientific studies have found a connection between these indicators with the exacerbation of schizophrenia, the nature of the course and its form, as well as the degree of mental defect.       

By combining the measurement of pro-inflammatory markers with the level of antibodies to brain proteins in the blood (protein S-100, myelin basic protein), a new tool for objectifying the diagnosis , Neurotest , was created , which increases the reliability of the detection and prognosis of schizophrenia and schizophrenia-like disorders.        

Instrumental methods

Instrumental examination methods – tomography, electroencephalography (EEG) – help to determine mental abnormalities in a person . With functional mental illness, they are used in a limited way, according to indications. The data from these examinations are useful for differential diagnosis. For example, magnetic resonance imaging is required when you need to make sure that mental symptoms are not associated with damage to brain tissue, blood vessels, or neuroinfection.     

Traditional studies of brain bioelectrical activity (EEG) in endogenous diseases such as schizophrenia show no specific abnormalities. More interesting results are obtained by an EEG recorded under conditions of exposure of the patient to sound, visual and other stimuli. Under these conditions, the so-called evoked potentials are recorded in the patient.        

In patients with schizophrenia, schizotypal disorder and predisposed persons, the parameters of some evoked potentials (components P50, P300, N400, NA) may differ significantly from healthy ones. These anomalies reflect the difficulty in recognizing signals, impaired memory and directed attention, and impaired cognitive functions in general. Some anomalies are associated with the severity, duration of the disease, its syndromes.        

Although special evoked potentials can occur in depression, strokes, brain trauma, alcoholism, their assessment, together with clinical data, helps the doctor in diagnosing schizophrenia and schizophrenia-like disorders.     

A more specific study for schizophrenia is the antisaccades test , which detects lack of smooth eye movement. This symptom occurs in almost 80% of people with schizophrenia and indicates a functional deficiency of the frontal cortex (“hypofrontality”). Since a similar defect is often demonstrated by healthy relatives of patients (genetic trait), a higher diagnostic sensitivity is achieved with a comprehensive electroencephalographic examination.       

Such a complex contains a test for antisaccades and tests with the determination of evoked potentials (P50 or P300). It is also advisable to measure the prestimulus inhibition of the startle reflex (SR), which reflects a person’s innate response (startle) to a sudden loud sound. Deviations of the startle reaction are observed in schizophrenia, already in the early stages of the disease. This diagnostic battery of EEG tests is called the Neurophysiological Test System .      

The methods described above for diagnosing mental illness are used in addition to clinical ones. They are based on the results of world research, represent different ways of recording biological changes that are characteristic of mental illness. The principle is the same as in other areas of medicine: after examination and conversation, the doctor prescribes clarifying examinations with various options – ultrasound, X-ray, analyzes. The aggregate of the obtained health data increases the accuracy of the diagnosis and minimizes errors .