Oftentimes experimental research centers around younger adults (18-30 years) who already study at the universities that a given project is conducted at. This makes it comparatively easy to identify, recruit, and study this particular population. By contrast, LLLL researchers often recruit more heterogeneous participant samples from the community or from healthcare centers. In other words, the process of recruiting participants can be difficult when conducting research with older adults, compared to younger populations. This section will give some practical considerations and tips for recruiting participants.
This section provides some practical considerations regarding recruitment. The table below gives a more succinct overview of benefits and drawbacks of several recruitment methods.
Leaflets.
Distributing leaflets is quite time-consuming and ineffective. For one study (the CogFlex project), over 200 leaflets were distributed in apartment blocks primarily inhabited by older adults, which led to fewer than five people signing up.
Facebook ads.
Facebook, on the other hand, can be a very effective and inexpensive tool to recruit participants who do not experience cognitive decline (e.g., viTAAL op leeftijd project). On the other hand, when recruiting participants with cognitive decline or mood disorders, this method has not been effective (CogFlex project).
Associations aimed at older adults.
Another effective way to recruit participants is through associations aimed specifically at older adults (University of the Third Age; older adults' advocacy networks; some specific hobby clubs). In general, people may not be very prone to participate based on an email invitation sent by someone they do not know. One useful way of convincing potentially interested people to participate is by giving a short lecture on the study. It is also useful to have a 'gatekeeper' (e.g., someone serving on a committee or board for one of these organizations) who can vouch for your study.
Reaching (pre-)clinical populations .
A drawback of using Facebook or other digital methods is that it biases the sample towards those with high digital skills, and with online social networks, in turn influencing the generalizability. For participant groups that are more difficult to reach (e.g., people with mild cognitive impairment or depression), we would recommend cultivating collaborations with hospitals (including, not limited to the psychiatry or geriatrics departments at the local university hospital and general practitioners) early on in the study development, or to search for platforms that connect participants and researchers (e.g., Hersenonderzoek.nl in the Netherlands).
| Method | Benefits | Drawbacks |
| Leaflets | Useful for targeting specific local clusters of older adults | Resource-intensive and not very effective |
| Facebook ads | Can reach participants nation-wide (and beyond) in a cost effective way. Known to be effective for healthy older adults | Not as effective for groups with clinically relevant symptoms (e.g., mild cognitive impairment; depression) |
| University hospitals | Suitable for reaching harder to reach populations | |
| Associations aimed at older adults; older adults' advocacy groups; University of the 3rd age; hobby clubs | Can be very effective if you have a 'gatekeeper' who can vouch for the study on your behalf | Participants in these networks are typically highly educated and very socially active, and as such results will only be representative for a very specific part of the population |
| Participants repositories Hersenonderzoek.nl (Netherlands) | Able to target your preferred population very accurately, as the repository can screen for some inclusion criteria (e.g., age) | May be costly |