Effects of smoking on cognition and BDNF levels in a male Chinese population: relationship with BDNF Val66Met polymorphism

Abstract

Recent studies demonstrate that brain-derived neurotrophic factor (BDNF) might be associated with nicotine addiction, and circulating BDNF is a biomarker of memory and general cognitive function. Moreover, studies suggest that a functional polymorphism of the BDNF Val66Met may mediate hippocampal-dependent cognitive functions. We aimed to explore the relationships between smoking, cognitive performance and BDNF in a normal Chinese Han population. We recruited 628 male healthy subjects, inducing 322 smokers and 306 nonsmokers, and genotyped them the BDNF Val66Met polymorphism. Of these, we assessed 114 smokers and 98 nonsmokers on the repeatable battery for the assessment of neuropsychological status (RBANS), and 103 smokers and 89 nonsmokers on serum BDNF levels. Smokers scored lower than the nonsmokers on RBANS total score (p = 0.002), immediate memory (p = 0.003) and delayed memory (p = 0.021). BDNF levels among the smokers who were Val allele carriers were correlated with the degree of cognitive impairments, especially attention, as well as with the carbon monoxide concentrations. Our findings suggest that smoking is associated with cognitive impairment in a male Chinese Han population. The association between higher BDNF levels and cognitive impairment, mainly attention in smokers appears to be dependent on the BDNF Val66Met polymorphism.

Plasma Brain-Derived Neurotrophic Factor (BDNF) Concentration and BDNF/TrkB Gene Polymorphisms in Croatian Adults with Asthma

“…Therefore, it is plausible that the nominally lower plasma BDNF levels seen in our female healthy subjects, showing no significant differences after correction for multiple testing, could be due to the lower weight of women than men in the control group. Regarding the association between smoking and BDNF levels, there are discrepancies in the literature, demonstrating lower [ 55 ], higher [ 56 ], or unchanged [ 57 ] concentrations of BDNF in the serum or plasma of smokers compared to nonsmokers. Though these reports on circulating concentrations of BDNF are inconclusive, it is important to recognize that cigarette smoke, at least partly through oxidative stress, has been shown to increase the expression of BDNF and its receptors in airway smooth muscle cells [ 58 ].…”

Neurotrophic Factor BDNF, Physiological Functions and Therapeutic Potential in Depression, Neurodegeneration and Brain Cancer

“…The BDNF Val66Met polymorphism has been associated with cerebral cortex plasticity [ 117 , 118 ], with gray matter structures [ 119 , 120 ], or white matter integrities and structural networks [ 121 , 122 ]. More specifically, BDNF Val66Met polymorphism is associated with cognitive processes [ 112 , 123 , 124 , 125 , 126 , 127 ], and cognitive impairment in neurodegenerative disease, such as Parkinson’s disease (PD) [ 128 , 129 ] and AD [ 130 , 131 ], and even more with several brain disorders, including MDD and bipolar disorder [ 132 , 133 , 134 , 135 , 136 , 137 ], epilepsy [ 138 , 139 , 140 ], schizophrenia [ 125 , 141 , 142 , 143 , 144 ], aging and dementia [ 145 ] and stroke [ 117 , 146 , 147 ]. Met66, but not Val66, BDNF pro-domain can induce the growth cone retraction in young hippocampal neurons [ 148 ].…”

Moderating Effects of BDNF Genetic Variants and Smoking on Cognition in PTSD Veterans

“…Nicotine could enhance aspects of cognitive function, including motor abilities, attention, and memory [ 22 ]. On the other hand, healthy smokers had lower cognitive scores and reduced immediate memory and delayed memory scores than non-smokers [ 23 ]. In agreement, long-term heavy smoking induced cognitive impairment and cognitive decline [ 24 ] and was associated with poor cognitive results in late life [ 25 ].…”

“…Literature data indicate circulating BDNF as a potential biomarker of memory and cognitive function in healthy adult subjects [ 36 ], but also in individuals with cognitive decline-related diseases, such as mild cognitive impairment [ 37 ], Alzheimer’s disease [ 38 ] and Huntington’s disease [ 39 ], which were characterized with the decreased levels of serum BDNF. A negative correlation was found between serum BDNF levels and attention in healthy smokers [ 23 ]. Additionally, preclinical data show that chronic nicotine administration increases brain derived neurotrophic factor (BDNF) mRNA levels in the dentate gyrus, CA3, and CA1 subfields of the rat hippocampus [ 40 ].…”

“…These findings suggest that BDNF rs6265 and BDNF rs56164415, as well as nicotine dependence, may play an important role in cognitive performance in PTSD. However, the role of BDNF rs6265 in cognition [ 23 , 52 ], especially in PTSD [ 57 ] is not clear, while data on the association of the BDNF rs56164415 and PTSD and cognition are missing. Therefore, this study aimed to evaluate changes in cognitive function in war veterans with PTSD and control subjects, controlled for the effect of smoking, and hypothesized that the A allele of the BDNF rs6265 and T allele of the BDNF rs56164415 is associated with cognitive decline in war veterans with PTSD.…”