Alcohol is the most commonly used worldwide. Alcohol consumption is one of the leading causes of death. Chronic alcohol intake can interfere with various physiological, biochemical and metabolic processes of the blood cells and affect multiple organ systems. Alcohol use, especially in heavy drinkers, can cause different metabolic derangements. Haematological adverse effects of acute and chronic alcohol use result from both direct and indirect effects [4,5]. The direct consequences include toxicity to the blood-forming organs (viz. bone marrow); the blood cell precursors; and the mature Red Blood Cells (RBC’s), White Blood Cells (WBC’s), and platelets, resulting in fewer than-normal or non-functional mature blood cells.
Substance use disorders cause tremendous burden to health care systems and society world-wide. As per the World Drug Report (2019) , about 35 million people worldwide suffer from drug use disorders. Disorders due to illicit drug use accounted for 10.9% of the DALYs caused by mental and substance use disorders and alcohol use disorders accounted for 9.6% . These drugs can be consumed either by inhalation, injection, or by ingestion. Alcohol and Substance use changes the body functions by influencing endogenous constituents of the bodies . These substances, when cross the blood-brain barrier on ingestion, may affect the brain function either depress or stimulate its activity and temporarily alter the chemical milieu of the brain. Long-term use of these addictive substances leads to serious damage to the nervous system and internal organs. Moreover, illicit drug uses are commonly linked with aplastic anaemia, bone marrow repression and variety of systemic disorders . Hence, early diagnosis of these disorders and identification of the complications they result in is important. Haematology is the branch of medicine that deals with blood, blood-forming organs and blood disorders. This article summarizes current information on the haematological changes that are observed in different substance use disorders and the utility of these changes in clinical assessment.
Cocaine is known to have vasoconstrictor effects in humans. Cocaine administration has been shown to increase the Hb level, RBC count and haematocrit through its transient effect of causing splenic constriction . However, there were no changes in the WBC or platelet count. These findings were replicated in a study that examined effects of intra-nasally snorted and intravenous cocaine administration . Contrary findings were seen in a study that examined the nutritional status of crack cocaine users in Brazil . The study found that the haematocrit level was less than normal in 36.4% of the sample and haemoglobin was less than normal in 32.4%. This study had the limitation that the use of other substances, including alcohol, was not an exclusion criterion.
There are a number of animal studies that looked into changes in haematological parameters after exposure to cannabis through different routes [34,35]. However, human studies are few and commonly have the limitation of small sample sizes. The effect of cannabis used through the smoking route on haematological parameters has been studied. Oseni, et al.  investigated the effect of marijuana smoking on haematological parameters between smokers and non-smokers. The findings suggest that the values observed for total leucocytes, neutrophil, lymphocyte, monocyte and platelet counts, though in normal range, were marginally lower in smokers, whereas values observed for PCV, haemoglobin and eosinophil were marginally higher. A published study from India  showed eosinophil counts to be high in 6% of cases, and neutrophil count abnormalities in 7.5% of subjects, which support previous studies on cannabis users . The lymphocyte counts showed a normal level while low mean relative monocyte count was observed . Another study from Pakistan compared Hb concentration, RBC count, WBC count and platelet count between cannabis smokers and healthy controls. They found significant increase in the leucocyte count of cannabis smokers as compared to controls. Also, eosinophils and monocytes values were significantly lower as compared to the control group. The study results showed slightly lower haemoglobin values in cannabis smoker group as compared to control group which could be due to poor nutrition of the smokers . These findings suggest that cannabis usage results in marked differences in some haematological parameters which may lead to inflammation, reduced immunity and ability to fight infections by users. A study from Turkey investigated alterations of the hematologic cells in synthetic cannabinoid users . They found synthetic cannabinoid user group differed significantly from a control group in terms of WBC, DLC, MPV, MCH, MCV and RDW. The MPV and the percentage of lymphocytes were lower in the group of synthetic cannabinoid users and the TLC, MCH, MC, RDW were higher compared to the control group. The findings suggest that chronic use of synthetic cannabinoids can lead to deterioration of hematopoietic cells. Thus, recovery of subclinical haematological parameters should be considered in cannabis use disorder patients. The health impact of cannabis-induced immunomodulation is still unclear and additional studies are needed in this area.
Tobacco use remains a global public health problem. Each year, tobacco use is responsible for approximately 8 million deaths worldwide (WHO, 2019) . Tobacco use is known to have effects on haematological parameters such as haemoglobin level and coagulability. It has been found that smokers have a significantly higher level of haemoglobin, haematocrit, MCHC and total and differential leucocyte counts [23,24]. It has also been shown that the increase in haemoglobin level is correlated positively with the duration of smoking. This can be explained by smoking resulting in increased carboxyhaemoglobins levels that causes hypoxemia and as the CO binds with Hb, functional anaemia is produced. The increase in the WBC counts could indicate the effect of release of catecholamines on WBCSs or the inflammation caused by smoking in the respiratory tract. The cessation of smoking for periods longer than one year has shown reversal of increased WBC counts . Although several studies have observed a positive association between smoking and total white blood cell counts, there have been some conflicting results for the subpopulations [23,25,26]. Also, conflicting results have been reported in the association between smoking and thrombocytes and some red blood cell indices too [26-29].
Shortly after graduating from China Medical School, Shaoguang Li, then a medical doctor, left to study in the United States. His primary interest was research with emphasis on leukemia. In the US, he studied at Tulane University in New Orleans earning his PhD degree for Cell and Molecular Biology. He went on to complete his post-doctoral degree at Harvard Medical School, obtained an appointment as Associate Professor at the University of Massachusetts and established his own lab. In the course of his work with Chronic Myeloid Leukemia (CML) he began to study a related blood disease, polycythemia vera (PV). This work produced a flash of insight.
What happened in Shenyang
Seen in this light, — the Mapquest approach to genomic targeting — the Big Idea seems a little inevitable. But before Professor Li could blow up any pathway bridges he would have to first find the bridge that lies on the JAK2 polycythemia vera pathway. And to do that he needed mice.
What happened in Chicago
A $150,000 per year, two-year grant was awarded to Shaoguang Li.