The NKT advertise themselves as teachers of mindfulness:

However, the NKT do not teach mindfulness in line with Western definitions aside from a brief breathing meditation at the beginning of classes used to induce a more suggestible state prior to focusing on doctrine (which includes practices that are actually oppositional to mindfulness practices).
Myself and the other survivors believe that the NKT saw an opportunity to draw the general public in by riding on the wave of the mindfulness movement and the public’s naivety about Buddhism. For more information on how the mindfulness movement made us vulnerable to Buddhist Cultic groups click here.
In my opinion, the mindfulness of breath led by the national spiritual director was poorly guided, as she began by stating ‘stop thinking about your family, friends, jobs, ordinary activities’ which is in fact a prompt, which is likely to cause someone to start thinking about these things, only to be told they must then immediately stop.
Dissociating from felt bodily experience
The NKT do not encourage practicing mindfulness of the body as it is not part of the lineage. They encourage only working on your mind, and believe that the body is simply created by the mind. The end result of this could therefore be that you may slowly lose touch with your body sensations the more time you spend engaging with their practices. Teaching people to focus on the ‘emptiness’ of their body when they do not feel connected to it in the first place, is likely to lead to dissociation and further repression of their emotions.
The importance of a strong, supple body, the ability to breathe deeply, and cope with bodily tension is never mentioned in any of the teachings, despite the effect these factors are
known to have on our mental state. Yoga is not encouraged as it is viewed as Hindu.
Dissociation
Research indicates that many people are often already disconnected from their felt bodily experience, but particularly those with a trauma history. Janet (1901) identified ‘dissociation’ of traumatic material from consciousness as a central defence against overwhelming experience. Here, dissociation provides a critical psychological escape from emotional and physical distress associated with overwhelming traumatic experience, including childhood, maltreatment war trauma, and torture, from which no actual physical escape is possible (Kluft, 1985; Nijenhuis, Vanderlinden, & Spinhoven, 1998; Putnam, 1996; Spiegel, 1984; Vermetten, Doherty, & Spiegel, 2007; Carlson, Yates, & Sroufe, 2009; Liotti, 2009; Schore, 2009). This type of escape can involve compartmentalization where ‘‘aspects of psychobiological functioning that should be associated, coordinated, and/or linked are not’’ (Spiegel, 2012; Spiegel et al., 2011, p. E19; also see Van der Hart, Nijenhuis & Steele, 2006) and detachment, including depersonalization, derealisation, and emotional numbing (Allen, 2001; Brown, 2006; Holmes et al., 2005; Spiegel & Cardena, 1991; Steele, Dorahy, Van der Hart, & Nijenhuis, 2009; Van der Kolk & Fisler, 1995). Later, however, as an individual attempts to resume normal functioning in the aftermath of trauma, chronic dissociation can have devastating consequences for all aspects of life (Brand et al., 2009; Jepsen, Langeland, & Heir, 2013). Given that the NKT do not screen people for trauma, and are likely to actively recruit them through their advertising, it is likely that they are teaching people who are already dissociated to dissociate further from their repressed emotional pain.
Hallucinations
It could be argued that through practicing NKT teachings which encourage applying opponents you may become less aware of your automatic thoughts and emotions. Imagining yourself as a deity and making offerings of beautiful flowers or reciting mantras in your mind will not improve your mindfulness skills, and it could be argued, interferes with your ability to be in touch with reality. When I lived at Nagarjuna KMC I heard people ‘rejoicing’ when other people stated that they were hallucinating Buddha’s before their eyes and in their dreams. These hallucinatory experiences are reframed as virtuous by the doctrine, therefore they are not seen as warning signs of deterioration. Once the person leaves the NKT however, these experiences are likely to persist, and others are likely to perceive them as mentally unwell.
It is my strong opinion and that of many others that it is not safe for mental health services to recommend or host meditation or ‘mindfulness’ classes run by the NKT.