en Behavioral Neuroscience Behavioral Neuroscience Original Original <div style="text-align: justify;"><strong>Introduction</strong>: A 40-Hz white light emitting diode (WLED) has emerged as an alternative nonpharmacological and noninvasive approach to Alzheimer disease (AD). Here, we investigated the therapeutic effects of 40-Hz WLED on psychiatric symptoms (PS) and the contribution of mitochondrial factors in the early stages of sporadic AD (sAD) in rats.<br> <strong>Methods</strong>: In male Wistar rats, the AD model was induced via intracerebroventricular (ICV) injection of streptozotocin (STZ). After recovering (7 days) from stereotaxic surgery, 40-Hz WLED exposure was performed for 7 consecutive days lasting 15 min/d. Behavioral (elevated plus maze (EPM), force swim test, and social interaction test), enzymatic, and molecular assays were conducted 24 hours after the last 40-Hz WLED exposure.<br> <strong>Results</strong>: Behavioral tasks revealed that 40-Hz WLED exposure in STZ-induced toxicity rats lowered anxiety and depression and increased social interaction. Furthermore, the 40-Hz WLED therapy in STZ-induced toxicity rats increased catalase (CAT) activity in the amygdala, decreased the activity of monoamine oxidases A and B in the whole brain, and increased mitochondrial DNA in the hippocampus.<br> <strong>Conclusion</strong>: The current study supports that 40-Hz WLED therapy improved PS and biomarkers in the early stages of sAD. Also, a potential relationship between PS and alterations in mitochondrial markers in certain brain regions seems to exist.</div> Alzheimer disease (AD), 40-Hz white light emitting diode (WLED), Psychiatric symptoms (PS), mtDNA, Monoamine oxidase (MAO), Catalase (CAT) 463 476 http://bcn.iums.ac.ir/browse.php?a_code=A-10-1856-1&slc_lang=en&sid=1 Elham Soleimani el.soleymani65@gmail.com 13700319475328460050108 0009-0001-2290-3644 No Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Abolhassan Ahmadiani aahmadiani@yahoo.com 13700319475328460050109 13700319475328460050109 Yes Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Maryam Bazrgar m.bazrgar8@yahoo.com 13700319475328460050110 13700319475328460050110 No Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Fariba Khodagholi khodagholi@sbmu.ac.ir 13700319475328460050111 13700319475328460050111 No Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Afsaneh Eliassi af.eliassi@sbmu.ac.ir 13700319475328460050112 13700319475328460050112 No Neurophysiology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.