Brain harm

Evidence that nicotine does not harm developing brains

2024: Prenatal substance exposure and child health: Understanding the role of environmental factors, genetics, and brain development

• "This research is among the first to systematically compare the developmental patterns of the health associations of prenatal exposures to four common substances in the context of both environmental and genetic risk-factor contexts. Notably, our findings revealed that associations of PSE-tobacco became statistically insignificant after considering environmental and genetic factors."

Twin studies refute nicotine causing any depression, anxiety, or IQ impairment (and longitudinal studies refute smoking causing ADHD).

2019: Drug and Alcohol Dependence Testing the reciprocal association between smoking and depressive symptoms from adolescence to adulthood: a longitudinal twin study.

• “In [the 74 identical] twin pairs discordant for ever smoking, the lifetime prevalence for [major depression] was essentially the same in the never-smoking and the ever-smoking members”

1993 Archives of General Psychiatry Smoking and major depression: a causal analysis.

• “No associations were found in within-pair analyses”

1989 Social Science & Medicine "Twins, smoking and mortality: a 12-year prospective study of smoking-discordant twin pairs

• Various psychological measures
• "personality factors (including measures of extraversion, neuroticism and perceived stress of daily life), life-changes and Type A behavior, occupational class, marital status and educational level were equally distributed among smokers and nonsmokers."

1988 Addictive behaviors (Table 4) Psychological characteristics in twins discordant for smoking behavior: a matched-twin-pair analysis.  

• no correlation between smoking & anxiety or depression