Cerebrospinal fluid somatostatin in delirium

A systematic literature review of cerebrospinal fluid biomarkers in delirium

BACKGROUND

Cerebrospinal fluid (CSF) analysis has great potential to advance understanding of delirium pathophysiology.

METHODS

A systematic literature review of CSF studies of DSM or ICD delirium was performed.

RESULTS

In 8 studies of 235 patients, delirium was associated with: elevated serotonin metabolites, interleukin-8, cortisol, lactate and protein, and reduced somatostatin, β-endorphin and neuron-specific enolase. Elevated acetylcholinesterase predicted poor outcome after delirium and higher dopamine metabolites were associated with psychotic features.

CONCLUSIONS

No clear conclusions emerged, but the current literature suggests multiple areas for further investigation with more detailed studies.

Discrimination of Alzheimer patients responding to cholinesterase inhibitor therapy

We have studied whether it is possible to discriminate responders to tacrine treatment from patients nonresponsive to tacrine in Alzheimer's disease. The results indicate that mildly demented patients will most likely gain a benefit of tacrine treatment. Neuropsychological tests on attention and working memory after a single dose of tacrine might be useful as well as a single dose pharmaco-EEG in discriminating responders to treatment.

The diagnosis of delirium in 80 emergency unit patients

We evaluated the initial and final diagnosis of 80 patients with delirium arriving at the emergence unit of a university hospital in a large Brazilian city over a period of 30 months up to December 1991. The diagnosis was based on the DSM-IIIR criteria. Patients with a known history of head trauma or epileptic seizure and patients younger than 13 years were excluded. Only patients with a disease of up to 7 days were included. The patients were subdivided into four etiologic groups: vascular; associated with the use of alcohol; infectious-parasitic; miscellaneous. The results showed a rate of correct diagnosis ranging from 65 to 80% with the use of kappa test (standard good to excellent). Sensitivity, specificity, positive predictive and negative predictive values had results showing different conditions for initial diagnosis in each group. This study can help the initial diagnosis of delirium and the choice for diagnostic testing.

Delirium in the elderly

Delirium is a state of disturbed consciousness and attention and cognition or perception, which develops acutely, fluctuates during the course of the day, and is attributable to a physical disorder. This syndrome is the focus of increasing attention in light of emerging evidence of its enormous impact in human suffering as well as patient care costs. As currently conceptualized, delirium is a threshold phenomenon in which systemic and cerebral insults are cumulative and, in most cases, are multifactorial in origin. Because delirium results from an underlying medical condition, its prognosis is dependent largely on how quickly that condition is identified and appropriately treated. A basic algorithm for initial delirium management is reviewed, which includes discontinuing noncritical medications, instituting close observation, monitoring vital signs and fluid intake and output, obtaining a complete history, performing initial laboratory studies to determine the causes, implementing environmental and psychosocial interventions, and instituting pharmacologic treatment as indicated for agitation and psychosis. The pharmacologic treatment of choice is an antipsychotic of the butyrophenone class. Benzodiazepine use is reserved for the specific treatment of alcohol and sedative withdrawal, and for adjunctive use with antipsychotic agents in treatment-refractory cases. There is growing evidence that the cognitive impairment of delirium is not entirely reversible in all patients, and it may be that delirium represents a time of significant risk for progression of underlying dementia. Preventive measures discussed in the text are, therefore, of particular importance in this population.

A critique of instruments and methods to detect, diagnose, and rate delirium

This document reviews existing instruments for evaluation of delirium. Instruments have been grouped into four categories: tests that screen for cognitive impairment, delirium diagnostic instruments, delirium-specific numerical rating scales, and laboratory and paraclinical exams. Analysis of instruments was based on comparison of their psychometric properties as well as subjective judgment. Guidelines are suggested for choosing the appropriate instrument according to the type of clinical evaluation or delirium research envisaged. Important factors in choosing an instrument, besides the appropriateness of its psychometric characteristics, include administration time constraints, level of rater expertise, and patient capabilities. By familiarizing investigators with the variety of evaluation instruments available, this work should permit more appropriate instrument selection in future studies on delirium.

Somatostatin in Alzheimer's disease and depression

Somatostatin (somatotropin release-inhibiting factor, SRIF) was originally discovered (1) during the purification of growth hormone-releasing factor from rat hypothalamus and was subsequently isolated and characterized (2) in 1972 from ovine hypothalamus. Since its initial characterization, SRIF has been shown to fulfill criteria for a neurotransmitter and to directly modulate neuronal activity as well as acting as an inhibitory factor regulating endocrine and exocrine secretion. Alterations in cerebrospinal fluid (CSF) concentrations of SRIF have been reported in several diseases exhibiting prominent cognitive dysfunction, including Alzheimer's disease (AD), major depression, Huntington's chorea, multiple sclerosis, schizophrenia and Parkinson's disease, while evidence for regional brain tissue concentration deficits in SRIF are more specific for AD. This mini-review will focus on the studies reporting alterations in CSF and postmortem tissue concentrations of SRIF in AD and depression.

Cerebrospinal fluid markers of Alzheimer's disease

OBJECTIVE

To review studies on cerebrospinal fluid (CSF) in patients with Alzheimer's disease (AD) in order to answer the question whether CSF contains a specific marker which can be used to support a clinical diagnosis of AD.

DATA SOURCES

Studies identified through an English-language literature search using MEDLINE (1966 to 1990) and a review of bibliographies of relevant articles.

STUDY SELECTION

All studies on CSF in AD patients were selected. Double publications on the same original data were not included. Otherwise, no particular selection was made.

DATA EXTRACTION

The diagnostic utility of more than 60 substances, including CSF measures related to classical neurotransmitters, (neuro)peptides, proteins, amino acids, purines, trace elements, and constituents of senile plaques and neurofibrillary tangles, is evaluated. Clinical epidemiological criteria for deciding on the usefulness of new diagnostic methods are emphasized in this analysis.

DATA SYNTHESIS

Concentrations of some CSF constituents are consistently found to be significantly changed in AD. However, overlap with data of control populations and methodological shortcomings in study design, limit the diagnostic value of all CSF measurements reviewed.

CONCLUSIONS

None of the CSF constituents studied so far can be used in support of the diagnosis of AD. However, increased knowledge concerning macromolecular abnormalities in amyloid containing plaques and neurofibrillary tangles makes the outlook for a diagnostic test for AD on CSF promising.

Somatostatin-like immunoreactivity in the CSF of patients with dementia associated with alcoholism

Cerebrospinal fluid somatostatin-like immunoreactivity (CSF SLI) was determined for 9 patients with chronic alcohol ingestion and dementia associated with alcoholism and for 8 age-equivalent controls. The CSF SLI was significantly reduced (32%) in the alcoholics with dementia as compared to the controls. This finding is in accordance with previous observations on the relationship between reduced CSF SLI and cognitive impairment in various neuropsychiatric disorders, and extends this finding to patients with dementia associated with alcoholism.

Decreased somatostatin-like immunoreactivity in the cerebrospinal fluid of chronic schizophrenic patients with cognitive impairment

The level of cerebrospinal fluid somatostatin-like immunoreactivity (CSF SLI) was determined for 11 chronic schizophrenic patients with moderate cognitive impairment and for 8 controls. The CSF SLI was significantly reduced (37%) in schizophrenic patients, but this decrease did not correlate with the degree of cognitive decline measured by the Mini-Mental State Examination, with psychotic symptoms estimated by the Brief Psychiatric Rating Scale, or with the neuroleptic dose. Although a reducing effect of long-term neuroleptic treatment cannot be totally excluded, the present study suggests that the CSF SLI level is decreased in cognitively impaired schizophrenic patients, as in many other disorders with cognitive impairment.

Cerebrospinal fluid somatostatin in delirium. II. Changes at the acute stage and at one year follow-up

Cerebrospinal fluid somatostatin-like immunoreactivity (CSF SLI) was determined for elderly delirious patients during the acute stage and after one-year follow-up. The SLI levels were compared with age-equivalent controls. For the group as a whole, and also when the group was subdivided according to the severity of cognitive decline at the acute stage, type of delirium, or the central nervous system disease, delirious patients showed significant reduction of SLI as compared with the controls. In the follow-up, we observed a further reduction of CSF SLI together with significant correlations in the second and third samples between SLI levels and Mini-Mental State Examination score. Our results suggest a role for somatostatinergic dysfunction in the genesis of some symptoms of delirium. This dysfunction may be a common phenomenon in various forms of delirium and dementia.