The present study aimed to examine the changes in cognitive function among addicted and non-addicted adolescents in Lucknow, Uttar Pradesh. A purposive random sampling technique was employed to select 200 adolescents aged 15-18 years from urban schools. The Cognitive Ability Test - Group Mental Level Battery (CAT-GMLB) was used to assess five domains of cognitive function: awareness, memory, understanding, reasoning ability, and problem-solving ability. Results revealed that reasoning ability and problem-solving ability significantly varied across age groups, with older adolescents showing a decline in these areas. Gender differences were significant only in memory, where girls performed better than boys. The mean scores indicated moderate levels of awareness (M=2.139), memory (M=2.129), understanding (M=2.568), reasoning (M=2.251), and problem-solving ability (M=2.373). Correlation analysis showed that online gaming addiction was negatively associated with understanding (r = -0.161, p < 0.05) and problem-solving ability (r = -0.200, p < 0.01), suggesting that higher gaming addiction impairs these cognitive domains. Furthermore, cognitive components were positively inter-related, indicating overall coherence among mental abilities. The findings highlight the adverse cognitive effects of excessive gaming and emphasize the need for preventive measures to promote balanced gaming habits and cognitive well-being among adolescents.