This study examined the neuropsychological profile of patients with Attention-Deficit/Hyperactivity Disorder (ADHD) based on Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) working memory and processing speed indices. We aimed to establish whether distinct ADHD subtypes emerge based on neuropsychological testing and determine whether ADHD subgroups differ based on neurocognitive and demographic factors in 179 adult patients with ADHD. Latent Profile Analysis (LPA) revealed four discrete latent subgroups within the sample, each with distinct patterns of working memory and processing speed. Classes significantly differed in demographically predicted IQ, education, and self-reported depression and anxiety. Results reveal heterogeneity in cognitive performance in adult ADHD.