Tuesday January 10 2012
Nicotine patches were shown to be safe for non-smokers
A small pilot study has suggested that nicotine may aid memory in early dementia, according to BBC News. During the study, researchers gave non-smoking elderly people with mild mental impairment either genuine nicotine patches or dummy patches containing no nicotine.
The 39 patients given genuine nicotine patches showed improvements in some, but not all, memory tests compared to the group that received the dummy patches. However, a medical assessment of overall functioning showed no difference between the two groups. Nicotine treatment was also shown to be safe in the people who received it.
As many newspapers rightly highlighted, this was a small pilot study and further research is needed to see if the results can be replicated in a larger group of people. Importantly, this study did not have a long enough follow-up period to see whether the nicotine treatment could prevent the participants’ mild mental impairment progressing to a more severe form of dementia. It is also not clear from this study whether nicotine could have any effect in treating Alzheimer’s disease, which is characterised by progressive memory loss over time.
Where did the story come from?
The study was carried out by researchers from Vanderbilt University in Nashville and other US universities. It was funded by the US National Institutes of Health, Aging and General Medical Sciences. The nicotine patches were provided by the pharmaceutical company Pfizer. The study was published in the peer-reviewed medical journal Neurology.
This study was covered appropriately by the newspapers, which highlighted the preliminary nature and small size of this study, both of which limit its implications.
What kind of research was this?
This small randomised controlled trial looked at whether nicotine patches improved cognitive performance and clinical status in people with mild cognitive impairment compared to inactive placebo patches.
Mild cognitive impairment is a small decline in cognitive function, greater than that which would occur with normal ageing but less than that which would be seen in forms of dementia, such as Alzheimer’s disease. People with mild cognitive impairment may go on to develop dementia, and researchers are keen to target this condition early to stop its progression. In Alzheimer’s disease, specific types of brain cell are affected, and it has been observed that brain cells in Alzheimer’s can lose nicotine receptors. These nicotine receptors are involved in passing on messages from one brain cell to another.
The researchers said that administering nicotine through a patch has been shown to improve cognitive function in some studies. The researchers wanted to see whether nicotine could improve cognitive function in non-smoking older patients, scored according to objective and clinical ratings.
What did the research involve?
Between 2004 and 2007, researchers recruited people aged over 55 who had a diagnosis of mild cognitive impairment (MCI), defined using clinical memory tests.
The researchers excluded people with significant current or prior medical or neurological disease, and people with head injuries or psychiatric illnesses including substance abuse. They also excluded people who had been taking medicines which might affect nicotine brain signalling and people who smoked or already used nicotine replacement.
The researchers randomly assigned 39 people to receive nicotine patches (15 mg/day) and 35 people to receive a placebo patch containing no nicotine. The patches were designed so that neither the participants nor the researchers doing the assessments knew which participants had received the placebo or nicotine. Although participants were randomly assigned treatments, it was done in a way that each group had equal numbers of people who were younger or older than 75, male and female and from each recruitment centre. In total, 34 people in the nicotine group and 33 people in the placebo group completed the study, which lasted six months.
Using standardised tests, the researchers assessed cognitive performance, behaviour, depression, how well the participants could perform day-to-day tasks and their nutrition at the start of the study. The same tests were repeated after 91 days and 182 days. The primary outcome was performance on a recognised cognition test called the Connors Continuous Performance Test (CPT). The researchers also assessed side effects of the treatment and how well the treatment was tolerated by assessing the number of drop-outs from the study.
What were the basic results?
The average age of the participants was 76 years, and there were no differences in the characteristics at the start of the study between the nicotine- and placebo-treated groups.
The nicotine group showed statistically significant better reaction time scores on one part of the Connors Continuous Performance Test. There was no significant difference between the nicotine and placebo groups on the global assessment made by clinicians.
The secondary outcome measurements looked at attention, memory and how quickly people could perform memory tests that required physical reaction. The researchers found better performance in the nicotine group. They also found that the patients’ ratings of their cognitive impairment were better in the nicotine group, who showed better scores in measurements of worries and anxiety, and anxiety and depression through two self-reported questionnaires. However, a formal assessment of depression showed no difference between the two groups.
How did the researchers interpret the results?
The researchers said that applying nicotine patches over six months is safe for non-smokers with MCI. They highlighted that this was a pilot clinical trial and that they had wanted to measure a broad spectrum of factors related to cognition and functioning. They were not surprised that the treatment did not affect all the measures. However, they said that the evidence on some measures of attention and memory suggest that nicotine improved scores, and that there is “strong justification for further treatment studies” in patients with early evidence of cognitive problems.
This small randomised controlled trial showed that six-month nicotine replacement for non-smoking older people with mild cognitive impairment was safe and improved scores on some memory tests compared to people who had a placebo treatment. The treatment did not improve scores on all the memory tests and an overall clinical assessment stated that there was no difference between the two groups.
The study had some limitations:
- The main limitation of this study was the small sample size.
- The study did not follow the participants over a long enough time to see whether there was a difference in the number of people who progressed to having more severe cognitive impairment (i.e. whether nicotine reduced progression of MCI).
- As this study was in people with mild cognitive impairment (and not dementia), it is not possible to say whether nicotine patches would have any effect in dementias such as Alzheimer’s, which is characterised by progressive memory loss.
Nevertheless, this study has shown that nicotine patches were well tolerated and will be followed up with larger and longer trials to see whether they have any protective effect for dementias.