: In an aging society, the number of people suffering from Alzheimer's Disease (AD) is still growing. Currently, intensive research is being carried out on the pathogenesis of AD. The results of these studies indicated that oxidative stress plays an important role in the onset and development of this disease. Moreover, in AD oxidative stress is generated by both genetic and biochemical factors as well as the functioning of the systems responsible for their formation and removal. The genetic factors associated with the regulation of the redox system include TOMM40, APOE, LPR, MAPT, APP, PSEN1 and PSEN2 genes. The most important biochemical parameters related to the formation of oxidative species in AD are p53, Homocysteine (Hcy) and a number of others. The formation of Reactive Oxygen Species (ROS) is also related to the efficiency of the DNA repair system, the effectiveness of the apoptosis, autophagy and mitophagy processes as well as the antioxidant potential. However, these factors are responsible for the development of many disorders, often with similar clinical symptoms, especially in the early stages of the disease. The discovery of markers of the early diagnosis of AD may contribute to the introduction of pharmacotherapy and slow down the progression of this disease.

Migraine is a common neurological disease that affects both women and men in a different age. It is believed that migraine is a multifactorial disease with strong genetic and environmental factors. Current molecular studies in migraine are focused on biochemical (homocysteine, asymmetric dimethylarginine) and genetic (ACE, MTHFR, MTR, MTRR, CBS, eNOS, NOTCH3) risk factors associated with vascular diseases. Polymorphisms and mutations in mentioned genes predispose to migraine as well as cardiovascular diseases and stroke. According to the literature data, 13-15% of migraine with aura patients suffer from vascular diseases, too. The strict relation between migraine with aura and stroke is observed in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy. Lifestyle plays an important role both in the pathomechanism of migraine and vascular diseases. Hypertension, obesity, dyslipidemia, and diabetes mellitus are the important risk factors for those pathological conditions. Therefore, early diagnosis of migraine and the implementing effective pharmacotherapy can lead to the prevention of cardiovascular and cerebrovascular diseases.

Parkinson's disease (PD) is divided into early-onset (EOPD) occurring at the age of fewer than 45 years of age and late-onset PD (LOPD) above 45 years of age. EOPD accounts for 5-10% of all the cases with PD. It is thought that occurrence in this age is connected with genetic factors, mutations in e.g. PRKN, PINK1, DJ-1 and changes in proteins it is encoded. The loss of dopaminergic neurons in the nigrostriatal system leads to decreased dopamine (DA) concentrations. Pathogenic PD proteins may affect the DA level. The lower level of DA may be responsible for movement-related symptoms. EOPDs have a slower progression of the disease and a longer disorder duration but tend to develop dyskinesias and motor fluctuations earlier than LOPD. Currently, the diagnosis of PD is based on clinical criteria, supported neuroimaging like MRI or PET. Understanding the pathogenesis of the EOPD may be contributing to improving diagnostics and effectiveness of pharmacotherapy.