Drug and alcohol addiction can cause diminished stores of dopamine and serotonin, the two feel-good chemicals that help to regulate mood. Both serotonin and dopamine can help you relax, prevent depression, and eliminate some post-acute withdrawal symptoms.  Some of these symptoms include: Inability to concentrate Insomnia Repetitive thinking Feelings of depression Feelings of anxiety Lacking initiative Cravings These symptoms can be lessened with proper nutrition and exercise. For example. You can help fight symptoms by adding more of these foods and healthy exercise into your new life style to increase your levels of dopamine. Addiction Can Also Cause Vitamin Deficiency Vitamins play a huge role in your overall health and have a direct impact on your energy levels and brain function. For someone battling addiction, malnutrition can cause a myriad of nutritional deficiencies which can lead to an inefficient ability to detoxify. Nutrient deficiencies can also lead to anxiety and depression, low energy and insomnia, memory issues, and issues with cognitive function.