Mental function

Air-poUutant effects on neural and sensory functions in humans vary widely. Odorous pollutants cause only minor annoyance yet, if persistent, they can lead to irritation, emotional upset, anorexia, and mental depression. Carbon monoxide can cause death secondary to the depression of the respiratory centers of the central nervous system. Short of death, repeated and prolonged exposure to carbon monoxide can alter sensory protection, temporal perception, and higher mental functions. Lipid-soluble aerosols can enter the body and be absorbed in the lipids of the central nervous system. Once there, their effects may persist long after the initial contact has been removed. Examples of agents of long-term chronic effects are organic phosphate pesticides and aerosols carrying the metals lead, mercury, and cadmium. 

This is the actual mental function required by the task that failed (see Figure 2.17). In the case study imder consideration the failure was at the Execute Action stage of the stepladder model, since the worker intended to operate the valve for reactor A, so there was no question of failure in the selection of actions. The connection with the task characteristics box indicates the fact that action is a fimction required by the task. 

Trace amines, most notably PEA, have been implicated in the etiology of depression. It has been suggested that trace amines stabilize mental functions within physiological limits, a hypothesis which might be in line with the assumed role of trace amines as... 

Nitroprusside 0.25-3 mcg/kg per minute BP, HR, liver and kidney function, blood cyanide and/or thiocyanate concentrations if toxicity suspected (nausea, vomiting, altered mental function)... 

Signs and Symptoms Sudden onset of fever, headache, vomiting and possibly abdominal pain, progressing to neck stiffness, mental confusion, motor disturbances, and difficulty with equilibrium. Survivors may suffer significant impairment of mental functions. 

In this interview Katy shares her view that chemical exposures can lead to an inability to tolerate stress, to loss of mental functioning, to fear and to violence. Since I met with her, two studies have been published that validate her remarks. One, a University of Wis-consin-Madison study published in the journal Toxicology and Industrial Health, January-March 1999, found that the pesticide-fertilizer mixtures commonly found in groundwater can affect patterns of aggression and the ability to learn, and causes hormone disruptions that increase sensitivity to stimuli, irritability and immune dysfunction. A University of Arizona study published by Environmental Health Perspectives in June 1998 showed a decrease in mental ability and an increase in aggressive behavior among children exposed to pesticides. 

Dementias. When the brain is damaged, mental functions are impaired. It starts as simple forgetfulness as the disease progresses, patients may... 

Memory Complex mental function having four distinct phases (1) memorizing or learning, (2) retention, (3) recall, and (4) recognition. Clinically, it is usually subdivided into immediate, recent, and remote memory. [NIH]... 

Senile dementia is another type of mental disease for which physical and chemical causes, aside from aging itself, are known. Cerebral arteriosclerosis is a every common accompaniment, and this is known to decrease the cerebral blood flow and the total metabolism of the brain. 11 This itself is enough to account for the deranged metabolism and the accompanying deranged mental functions. 

Alzheimer s Disease The vaccine being tested contains a small protein called jS-amyloid (AjS). This protein forms abnormal deposits, or plaques, in the brains of people with Alzheimer s disease. Researchers believe that Kji deposition causes loss of mental function by killing the brain neurons. The strategy of Aji vaccination is to stimulate the immune system to clean up plaques and prevent further A deposits. Although preclinical and Phase I studies showed the potential of the vaccine, the Phase II clinical trial was halted because 15 of 360 patients developed severe brain inflammation. Further studies showed that the A did generate the desired... 

Delirium tremens (the D.T.s ) resulting from alcohol withdrawal is slightly different in that it is usually preceded by the shakes, convulsions and occasionally by alcoholic hallucinosis - characterized by accusatory auditory hallucinations. As observed 60 years ago by Maurice Victor, an expert on alcohol problems, delirium tremens usually does not appear until day 3 or 4 following abrupt withdrawal from alcohol. The patient is generally malnourished and grossly deficient in vitamin Bj (thiamine) as the result of a diet consisting of little but alcohol. This deficiency ftirther compromises mental function. 

Each mental function in the brain—from the simplest reflex to the most creative acts in language, music and art—is carried out by specialized neural circuits in different regions of the brain. 

Her case is one of a great many in which some decline in optimal mental function compromises life. These compromises fall into two general categories, whose distinction may be less real than apparent. On the one hand, there are neurological diseases in which there is some detectable, definable lesion in the nervous system. In the last chapter, we met one notable example Alzheimer s disease. As mentioned then, Alzheimer s disease is characterized by amyloid plaques external to neurons and fibrillary tangles within them—clear lesions. On the other hand, there are psychiatric diseases in which the pathology is clear but for which we can detect no lesion in the nervous system. Depression and schizophrenia provide two important examples. 

Figure 7.21 Provision of the fat fueb for the brain during hypo-glycaemia. During hypoglycaemia it is essential that ketone bodies are available for the brain to provide a fat fuel for ATP generation to maintain mental functions. This sequence of processes from adipose tissue to the brain is therefore, a survival pathway especially for children during short-term starvation or hypoglycaemia. (Box 7.2) (Chapter 16).

Risk analysis and risk management play an important role in public policy. These debates range from the development of environmental impact statements for the location of buildings to debates on household lead abatement and what chemicals can be allowed in the food supply. Quality of life issues such as asthma and/or loss of mental function are now recognized as important components of risk assessment. 

Recent evidence suggests possible progressive deterioration in mental function, eg, declining IQ after adult PKU patients suspend the Phe-restricted diet. 

Degeneration of these same neurons is also associated with an age-dependent decrease in learning and memory ability. Infusion of NGF and NT-4/5 to aged rats appears to improve their spatial memory ability. Further studies in rodents have shown that physical exercise increased BDNF expression, which may explain why exercise is often a predictor of high mental function during ageing. 

Amantadine was originally introduced as an antiviral compound (see Chapter 50), but it is modestly effective in treating symptoms of parkinsonism. It is useful in the early stages of parkinsonism or as an adjunct to levodopa therapy. Its mechanism of action in parkinsonism is not clear, but amantadine may affect dopamine release and reuptake. Additional sites of action may include antagonism at muscarinic and A-methyl-D-aspartate (NMDA) receptors. Adverse effects include nausea, dizziness, insomnia, confusion, hallucinations, ankle edema, and livedo reticularis. Amantadine and the anticholinergics may exert additive effects on mental functioning. 

Stimulant, CNS. A compound that excites mental function. 

Prince DA, Wilder BJ Cortical mechanisms in cortical epileptogenic foci surrounded inhibition. Arch Neurol 16 194-202, 1967 Prinz PN, Vitahano PP, Vitiello MV, et al Sleep, EEC and mental function changes in senile dementia of the Alzheimer s type. Neurobiol Aging 3 361-370, 1982... 

Alcohol is not the only chemical that causes one to become impaired and drive erratically. Any chemical that affects mental functions, including some common prescription drugs as well as controlled substances, can impair the ability to drive. 

---