Central nervous system impairment caused by chronic solvent abuse - a review of Japanese studies on the clinical and neuroimaging aspects

Organic solvents are some of the most frequently abused substances in Japan. Abuse is especially prevalent among young people. In this article, we review Japanese studies, along with those of other other countries, on central nervous system impairment caused by chronic solvent abuse. Neuroimaging studies provided valuable information on this problem. Magnetic resonance imaging revealed T2 prolonged lesions in diffuse white matter which were related to neurological symptoms and cognitive dysfunction. Clinical observations indicated that neurological symptoms and their reversibility differed among patients. Histopathological studies similarly revealed variation in severity of brain damage reflected by demyelination and neuronal damage. The basis of these variations are yet to be elucidated along with their causes such as severity of dependence, composition of solvents, individual predispositions and starting age of abuse. Cerebral perfusion analyses revealed some regional decreases in blood flow. These decreases may occur earlier than white matter changes and may relate to psychiatric symptoms such as apathy and lack of initiative.