Subjective memory complaint (SMC) and restriction in cognitively-complex activities of daily living (such as instrumental ADL) are two early symptoms observed in the prodromal phase of dementia and may represent useful alarm signals for general practitioners for an increased risk of subsequent dementia. We here studied in a large population-based epidemiological cohort on aging, the risk of dementia associated with SMC and restriction in IADL, with a specific interest in a potential interaction by gender. The sample included 2,901 subjects, aged 65 years and over, initially free of dementia and followed over 15 years. After controlling for education, marital status, depressive symptomatology, and global cognition (MMSE), IADL-restriction was associated with an increased risk of dementia only in men (HR = 2.04, 1.27 to 3.29), whereas SMC was not (p = 0.95). The reverse was observed in females, in whom SMC almost doubled the risk of dementia (1.48 to 2.41), with no association with IADL-restriction (p = 0.74). Finally, we distinguished the risk of dementia at short-term (in the first 5 years), mid-term (between 5 and 10 years), and long-term (between 10 and 15 years). In women, SMC was significantly associated with greater risk of dementia whatever the risk period considered, even at longer term (HR = 1.61, p = 0.0216), whereas in men the increased risk was also observed with IADL-restriction and only in the first 5 years. To conclude, women would report the first symptoms very early in the process by SMC, whereas men would tend to later report their difficulties and only in terms of IADL-restriction.