Heavy alcohol consumption causes damage to the central nervous system through numerous mechanisms. One of the proposed mechanisms is the reduced availability of an essential nutrient, thiamine, to the brain (Martin et al., 2003; Singleton and Martin, 2001). Thiamine, also known as vitamin B1, is an essential nutrient and plays an important role in metabolic and cellular function. In the human body, high concentrations of thiamine are found in skeletal muscles, heart, liver, kidney, and brain (Martin et al., 2003). Thiamine diphosphate is the active form of thiamine and serves as a cofactor for several enzymes involved in carbohydrate catabolism. In addition to their critical role in carbohydrate and energy metabolisms, thiamine and thiamine-utilizing enzymes regulate brain excitability and synthesis of neurotransmitters, nucleic acids, fatty acids, and steroids (Martin et al., 2003). Several mechanisms for alcoholism-induced thiamine deficiency (TD) have been proposed, and these include: (i) inadequate nutritional intake in alcoholics; (ii) decreased absorption of thiamine from the gastrointestinal tract and reduced uptake into cells due to alcohol exposure; and (iii) impaired utilization of thiamine in the cells due to alcohol exposure (Gastaldi et al., 1989; Hoyumpa, 1980; Martin et al., 2003). Wernicke–Korsakoff syndrome (WKS) is a devastating neurological disorder characterized by oculomotor disturbances, ataxia, and mental confusion; it is believed that TD plays an important role in WKS pathogenesis (Harper, 2006). TD-induced WKS can be replicated in animal models using pyrithiamine alone or in combination with alcohol (He et al., 2007; Langlais et al., 1996; Zimitat et al., 1990). Chronic alcohol consumption is sometimes associated with WKS (Victor et al., 1989). The conventional idea is that WKS develops as a result of TD, and alcohol per se has no direct deleterious effects on the brain. The concept is challenged by subsequent studies in animals and humans showing that ethanol adversely affects brain structure and function probably due to direct neurotoxicity (Harper and Matsumoto, 2005; Ron, 1982). It is unclear whether the brain damage seen in chronic alcoholism is caused by one of these factors or by the association of both. Alcohol causes neuronal loss in specific regions of the human brain, such as the superior frontal association cortex, hypothalamus, and cerebellum (Harper, 1998). The cerebellum is particularly susceptible to alcohol exposure, and chronic alcohol consumption is frequently accompanied by cerebellar degeneration (Baker et al., 1999; Martin et al., 2003). The shrinkage and degeneration of Purkinje cells in ethanol-dependent individuals is associated with ataxia of the lower limbs (Andersen, 2004; Sullivan et al., 2000). Interestingly, the degeneration of Purkinje cells is more marked in patients suffering from Wernicke’s encephalopathy (Baker et al., 1999). The etiology of alcoholic cerebellar degeneration is still a matter of debate. As the cerebellum is also sensitive to TD (Martin et al., 2003; Mulholland, 2006), some speculate that TD in alcoholics may be the cause of cerebellar damage (Charness, 1993; Diamond and Messing, 1994; Harper and Kril, 1990; Joyce, 1994; Maschke et al., 2005). However, animal experiments provide evidence of direct neurotoxicity of ethanol on cerebellar neurons (Fadda and Rossetti, 1998; Rajgopal et al., 2003; Tavares et al., 1987). Cerebellar atrophy may occur in alcoholics without malnourishment (Nicolas et al., 2000). The relationship between ethanol and TD and the contribution of their interaction to neurotoxicity remain to be elucidated. The double-stranded RNA (dsRNA)-activated protein kinase (PKR) is a serine/threonine protein kinase ubiquitously expressed in mammalian cells (Williams, 1999, 2001). PKR is initially identified as an interferon-induced protein that is activated in virus-infected cells by dsRNA produced during the virus life cycle (Tan and Katze, 1999; Ung et al., 2001). PKR consists of 2 functionally distinct domains: a N-terminal dsRNA binding regulatory domain and a C-terminal catalytic domain. When PKR binds to dsRNA it causes PKR to form homodimers and to autophosphorylate on multiple serine/threonine residues including Thr446 and Thr451, resulting in PKR activation (Williams, 1999, 2001). In addition to dsRNA, PKR can be activated by cytokines, growth factors, serum deprivation, disruption of intracellular Ca2+ homeostasis, oxidative stress, and endoplasmic reticulum (ER) stress (Patel and Sen, 1998; Patel et al., 2000; Shimazawa and Hara, 2006; Wang et al., 2007a,b; Williams, 1999, 2001). Activation of PKR leads to an inhibition of protein synthesis, and sometimes apoptosis in the cells (Saelens et al., 2001; Williams, 1999, 2001). We have previously shown that TD activates PKR in vitro and in vivo (Wang et al., 2007a). In this study, we use an in vitro model, cultured cerebellar granule neurons (CGNs), to investigate the interaction between TD and ethanol and evaluate the contribution of their interaction to neuronal loss. We show that ethanol promotes TD-induced death of CGNs and that PKR plays an important role in the interaction.