Olfactory function declines with age, affecting both quality of life and cognitive abilities. Research suggests olfactory training (OT)—the repeated exposure to specific scents—may help maintain or restore olfactory function while also benefiting cognitive and emotional well-being. The purpose of this review was to examine the extent to which OT can improve olfactory function, cognition, and well-being in older adults, including those with cognitive impairments such as mild cognitive impairment (MCI) and dementia.

The researchers conducted a scoping review of existing literature, analyzing 23 studies that included adults aged 55 and older who underwent OT. Studies were sourced from major academic databases, including PubMed, Embase, EbscoHost, and SCOPUS. The review aimed to determine whether OT influences olfactory ability, cognitive function (e.g., verbal fluency, working memory), and mental health (e.g., depressive symptoms).

The results showed consistent improvements in olfactory function across different training methodologies, particularly in odor detection thresholds and discrimination ability. Among older adults, OT was associated with improvements in semantic verbal fluency and working memory, key cognitive functions that are often affected by neurodegenerative diseases like Alzheimer’s. Additionally, some studies found a reduction in depressive symptoms, further reinforcing the connection between olfaction and emotional well-being.

Olfactory dysfunction is strongly correlated with aging and neurodegenerative diseases, with up to 80% of individuals over 80 experiencing significant smell loss. The review highlights that olfactory impairment often goes unnoticed, as it is rarely tested for clinically, even though it has been linked to increased mortality risk. Since olfactory pathways are closely tied to brain regions involved in memory and emotion, OT could serve as a low-cost, non-invasive intervention for supporting cognitive health.

The methodology of OT varied across studies, but classical olfactory training (COT)—involving twice-daily exposure to four core odors (rose, eucalyptus, lemon, and cloves) for 12 to 56 weeks—was the most commonly used approach. Some studies introduced modifications, such as rotating odorants or incorporating natural household scents. The most significant improvements in olfactory function occurred between weeks 13 and 18, suggesting that sustained training is required for noticeable benefits.

A particularly interesting finding was that OT showed promise even for individuals with MCI and dementia. While results varied, some studies demonstrated that OT improved verbal fluency and cognitive performance in those with cognitive impairments, though others found no significant effect. The strongest and most consistent cognitive improvements were seen in semantic verbal fluency, which is a critical function for language and memory.

One major limitation identified in the review was the lack of standardized adherence measures. Many studies relied on self-reported “smell diaries,” and some did not track compliance at all. This makes it difficult to determine the exact impact of OT, as participant adherence plays a crucial role in its effectiveness. Another limitation was that most studies did not differentiate between types of dementia, which could affect how OT benefits different neurodegenerative conditions.

Overall, the review concludes that olfactory training is a promising, low-cost intervention for maintaining olfactory function, cognitive abilities, and mental health in aging populations. While more research is needed—especially in neurodegenerative conditions—these findings suggest that OT could be a valuable tool for preventing cognitive decline and enhancing overall well-being.