Link between cigarette smoking and IQ

The study involved 74 non-smokers with amnestic MCI (average age 76), of whom half were given a nicotine patch of 15 mg a day for six months and half received a placebo. Cognitive tests were given at the start of the study and again after three and six months.

After 6 months of treatment, the nicotine-treated group showed significant improvement in attention, memory, speed of processing and consistency of processing. For example, the nicotine-treated group regained 46% of normal performance for age on long-term memory, whereas the placebo group worsened by 26%.

In the last five years, three studies have linked lower neighborhood socioeconomic status to lower cognitive function in older adults. Neighborhood has also been linked to self-rated health, cardiovascular disease, and mortality. Such links between health and neighborhood may come about through exposure to pollutants or other environmental stressors, access to alcohol and cigarettes, barriers to physical activity, reduced social support, and reduced access to good health and social services.

Binge drinking is, unfortunately, most common among adolescents (12-20 years). But this is a time when brains are still developing. Does this make them more vulnerable to the detrimental effects of excessive alcohol?

Comparison of the brains of 22 smokers and 21 people who have never smoked in their lives has revealed that the left medial orbitofrontal cortex of the smokers was on average smaller than that of the non-smokers. Moreover, this reduction was greater the more cigarettes were smoked daily, and as a function of how long they had smoked. The region is involved in reward, impulse control, and decision-making, suggesting that fewer neurons there may mean you have to work harder for reward, and that your ability to curb your impulses and make decisions is impaired.

Data from 21,123 people, surveyed between 1978 and 1985 when in their 50s and tracked for dementia from 1994 to 2008, has revealed that those who smoked more than two packs per day in middle age had more than twice the risk of developing dementia, both Alzheimer's and vascular dementia, compared to non-smokers.

A quarter of the participants (25.4%) were diagnosed with dementia during the 23 years follow-up, of whom a little over 20% were diagnosed with Alzheimer's disease and nearly 8% with vascular dementia.

A 12-year study following the drinking and smoking habits of 22,524 people aged 39-79 has found that in non-smokers, people who consumed moderate amounts of alcohol were 37% less likely to develop stroke than non-drinkers. This association was not found among smokers. The finding may explain the inconsistency in previous studies into the relationship between light to moderate drinking and stroke.

Data from 196,383 older adults (60+; mean age 64) in the UK Biobank found that a healthy lifestyle was associated with lower dementia risk regardless of genes.

Both an unhealthy lifestyle and high genetic risk were associated with higher dementia risk.

There are five healthy behaviors that appear to significantly reduce the risk of dementia,

A large meta-analysis has concluded that having diabetes increases the chance that a person with mild cognitive impairment will progress to dementia by 65%.

There was no consistent evidence that hypertension or cholesterol levels increased the risk of someone with MCI progressing to dementia. Smoking was similarly not associated with increased risk, although the reason for this probably lies in mortality: smokers tend to die before developing dementia.

Brain scans of 9,772 people aged 44 to 79, who were enrolled in the UK Biobank study, have revealed that smoking, high blood pressure, high pulse pressure, diabetes, and high BMI — but not high cholesterol — were all linked to greater brain shrinkage, less grey matter and less healthy white matter.