From psychophysiological insomnia to organic sleep disturbances: a continuum in late onset insomnia - with special concerns relating to its treatment.

The population suffering from insomnia in old age onset (LOI) is quite large. LOI might include a larger scale of syndromes ranging from typical psychophysiological insomnia to night delirium. The correlation between the biological, biochemical changes and the quantitative as well as the qualitative alterations of the sleep process through aging has not been fully explored. One can suppose that any cerebral lesion leading to a dysfunction in mental performance can also act on the sleep. The majority of LOI brain metabolic disturbances might therefore have some etiological role. The authors suggest the application of this concept in the clinical evaluation of LOI. The authors constructed a heuristic model for the pathophysiology and treatment of LOI. It is a bipolar axis containing the most typical symptoms of LOI. On the opposite margins psychophysiological insomnia and organic/metabolic insomnia (up to delirious states) are settled. The position on the axis (i.e., its distance from the "edge syndromes") gives information on the probability of its organic nature. Based on their clinical experiences and considering the data of the very few studies, they suppose that with the help of a detailed analysis of the symptoms of LOI and using some additional (electrophysiological and neuroimaging) laboratory methods most patients with LOI can get a strict diagnostic position on the LOI axis. Using the LOI axis not only a detailed evaluation of the symptomatology but also more sophisticated therapeutic interventions become possible. Symptoms on the "metabolic side" can be cured by a single evening application of any drugs improving the function of the brain (like nootropics, neuroprotective agents or even slight stimulants, e.g., caffeine) might show a "paradoxical hypnotic" effect, or in combination with sleeping pills they can cause an additive effect in LOI patients. The efficacy of this treatment can also have a diagnostic value: i.e., it helps to differentiate between the primary (organic) and psychophysiological (exogenous or emotional/psychic) forms of LOI.

[Event-related EEG and evoked potential investigations in clinical practice]. / Eseményfüggo EEG- es kiváltottválasz-vizsgálatok a klinikai gyakorlatban.

Considering the limits of the traditional EEG techniques the authors review the main methods and clinical importance of the event-related EEG investigations. According to methods, these can be classified into the spectral analysis of task-related, pre-task and post-task recordings as well as stimulus-controlled measurements based on evoked potential techniques. The main results of clinical studies on the event-related EEG methods are summarized according to chief disease groups (Alzheimer's disease, epilepsy, schizophrenia, Parkinson's disease, dyslexia, depression). The authors discuss the stimulus-dependent EEG discharges (P300, cognitive potential) in detail. They present the meta-analysis of 224 recent publications on human application of these methods. They analyze the involved scientific areas and the frequency by which these methods were applied in each. Following this, the results of 83 selected clinical studies are summarized. The frequency of the application of the various event-related EEG methods and the tested wave components and other parameters are listed. Finally a summary of the main clinical results is presented again by groups of diseases (schizophrenia, behavioral disorders, traumatic lesions, enuresis nocturna, depression, memory disturbance and dementia, drug effect). Finally, the potential perspectives and the limitations of the event-related EEG methods are briefly discussed.