Nicotine is a widely seen drug found in tobacco products. It is usually associated with the negative effects of smoking, including the addiction and cravings. However, nicotine can be helpful for people with pathological disease states such as Alzheimer’s disease, Parkinson’s disease, attention deficit/hyperactivity disorder and schizophrenia. A recent study done here at UVM investigated the cognitive improvements of three groups: smokers, normal volunteers, and contrasts those with trials of nicotinic stimulation in pathological disease states. Chemical receptors for nicotine are found all throughout the central nervous system, and stimulating parts of the brain with nicotinic acid have shown to be vital to memory function. Nicotinic acid is a B vitamin found in yeast, liver, eggs, and other foods and is also known as niacin, or vitamin B3.
Studies have shown that administering nicotine in low doses independent of tobacco is relatively safe and has a low abuse rate. The behavioral effects of nicotine are complex and depend on the amount you take, how it gets into your body, gender, and personality. This makes simple classification of nicotine as either a stimulant or depressant difficult. In the absence of nicotine withdrawal symptoms, nicotine will improve the performance of smokers on tasks demanding attention and logic. For smokers, or other people addicted to nicotine, cognitive performance is generally diminished during withdrawal symptoms, and does not return to normal levels when given a nicotine patch. In general, studies previous to this one showed that administration of nicotine improves response time, but impairs memory, attention to details while reading, and motor functions. Another study showed that compared nicotine with donepezil showed there to be equal improvements with each, though the nicotine was given as one dose and the donepezil was taken for a month before the testing was done. Donepezil is also known as Aricept, and is used to treat Alzheimer’s disease. In the autopsied brains of Alzheimer’s disease patients, a lower number of nicotine receptors were found than in normal brain tissue. The receptors lost are of a type called á4â2, which is one of the major receptors for nicotine in a mammals brain.
Nothing in the above has touched on the issue yet, which is the use of nicotine to help those with pathological disease states. In the treatment of mild cognitive impairment, nicotine patches were worn for up to sixteen hours per day, and those who got nicotine as opposed to the placebo performed significantly better than before receiving the treatment, with nicotine improving the decision making portion of reaction time far more than sped up the actual movement. It also improved the accuracy of answers in another cognitive test. For those with Alzheimer’s disease, the main improvement that nicotine caused was a reduction in errors in the new learning phase of a task and improvements in attention related task performance. This might be due to the simple activation of the nicotine receptors in the brain and central nervous system, or cause a cascading effect involving other neurotransmitters. For Alzheimer’s disease, treatment with nicotine may turn out to be difficult, due to the loss of receptors in the patient’s brain. For Parkinson’s disease, both acute and chronic effects were studied, with improvements in both motor skills and reaction times. Effects were seen for many weeks after treatment ended. However, when added to existing Parkinson’s disease medicine, no additional improvement was seen in the patients. In schizophrenic patients, smoking is more common, perhaps due to the ability of nicotine to lessen the symptoms of the disease, as it improves memory, attention span, and spatial perception. Those with ADHD also smoke at higher rates than the general population, and in this study current smokers recalled a greater number and severity of ADHD symptoms in childhood. ADHD sufferers benefit from nicotine, gaining greater concentration abilities and better response time.
The authors of this study suggest that earlier negative results on the effects of nicotine were due to the fact that they used normal and non-smoker populations, whose cognitive performance is already at peak for the individual. The nicotine has a detrimental effect on the performance of the individual, while those who are impaired tend to show improvement when given nicotine. This seems to suggest that intermediate levels of stimulation with nicotine produce optimal results, and in those individuals who do not either respond to nicotine as strongly as the general population or ingest nicotine compounds in foods are helped by nicotine patches or injections. Too much or too little nicotine has a detrimental effect on the brain. The conclusion reached in this study is that nicotine has the greatest effect on tasks requiring attention. The authors suggest that short or impaired attention, impaired thinking and executing tasks are separate from the disease diagnosis and that nicotine and its receptors should be considered as a target for drugs for those with Alzheimer’s, Parkinson’s, or ADHD.