## 4 Discussion  
It has been reported that neuroinflammatory processes in drug addiction disorders can lead to neurodegeneration in specific brain areas [16]. According to independent research, the prevalence of neurodegenerative disease and dementia is significantly higher among AMPH-adds [17; 18; 19]. Currently, this is the first study to measure neurodegenerative biomarkers in serum from AMPH-adds. AMPH-adds showed a significant increase in ACT compared to control healthy subjects in the current study; as a result, AMPH-adds may exhibit early symptoms of AD. Serine protease inhibitors include ACT and SERPINA3, which are members of the acute-phase protein family [20]. While liver cells predominantly synthesize ACT, brain cells, primarily astrocytes, also produce it. Furthermore, there is a connection between high ACT levels in plasma, serum, and cerebrospinal fluid (CSF) in patients with AD and a cognitive decline in elderly individuals [18]. According to this evidence, ACT may serve as a biomarker for early diagnosis. In addition, ACT catalyzed amyloid \(\beta\)-peptide polymerization in vitro, an acute-phase inflammatory protein that contributes to amyloid deposits in AD [21]. A high level of interleukin (IL)-1 \(\beta\) is expressed by microglia around plaques in AD brains, which correlates with the severity of the pathology. In response to these elevated levels of A \(\beta\), there is an inflammatory response leading to an increased expression of proteins associated with inflammation, such as IL-1\(\beta\), ACT, and complement factors [2; 3]. In addition, astrocytes stimulated by IL-1 \(\beta\) express higher ACT levels, and the amyloid precursor protein was translated more efficiently [4; 21]. According to studies identifying ACT as associated with Alzheimer's amyloid plaques and is expressed exclusively in regions with IL-1 \(\beta\) overexpression, these findings suggest that this coupled expression may play a significant role in disease pathogenesis [21]. Compared to healthy control subjects, AMPH-adds had a significant increase in PEDF. In AMPH-adds, PEDF concentration in serum is important as a predictor of AD based on the concentration of PEDF in the serum. To the best of our knowledge, there are no previous studies performed to measure PEDF in AMPH-adds or any other substance users. However, one study showed a significant increase in PEDF levels in the serum of eight alcohol users [22]. Neurotrophic and neuroprotective protein PEDF, a 50-kDa molecule expressed widely in the nervous system plays a role in neuroregulation [23]. PEDF protects against insults such as quinolinic acid excitotoxicity and glutamate excitotoxicity [23]. In addition, PEDF can attenuate ischemic brain damage [24; 25]. According to [PERSON] and his colleagues, PEDF exhibits strong immunoreactivity in astrocytes and cortical neurons in [PERSON]'s brains [24]. In addition, the presence of PEDF proteins was well-correlated with the presence of the receptor for advanced glycation end products (RAGE), one of the receptors for amyloid \(\beta\) peptides, which are involved in the death of neuronal cells and the activation of microglial cells in AD [14; 19]. They also suggested that PEDF may provide an indicator of PEDF turnover in the brain and be used to measure neuronal disruption induced by oxidative stress in AD [25]. Accordingly, [PERSON] et al. studied PEDF levels in paired CSF and serum samples by ELISA in people with Alzheimer's disease, frontotemporal dementia, vascular de mentia, multiple sclerosis, pseudotumor cerebri, and other non-inflammatory neurologic diseases [26]. They established CSF/serum quotient diagrams to determine the fraction of intrathecally synthesized PEDF in CSF. In patients with AD, frontotemporal disorders (FTD), and bacterial meningitis, PEDF levels are significantly higher. Patients with AD also had significantly elevated PEDF concentrations in their serum [27]. PEDF can be used clinically as a biomarker to assist in more accurate diagnosis and the treatment of patients suffering from AD.