This is a single-centre research study in patients seen within an NHS Improving Access to Psychological Interventions (IAPT) service with suspected generalised anxiety disorder (GAD). The study will involve 120 patients from the Leicestershire and Rutland area in England, United Kingdom.

Participants will use the Alpha-Stim AID Cranial Electrotherapy Stimulations (CES) medical device, which is approved for use and proven to be safe and work for the treatment for anxiety, depression and insomnia.

Participants will use the Alpha-Stim AID for 60 minutes every day for 6 or 12 weeks, either whilst on the waiting list for standard care treatment from IAPT, or in conjunction with standard care treatment from IAPT.

The study will involve 6 study visits - one face-to-face at visit 1, followed by 5 visits via telephone at week 4, 6, 8, 12 and 24. At each visit, participants will be asked to complete questionnaires to assess anxiety, depression, sleep difficulty, quality of life and work and social functioning.

The purpose of the study is to gather evidence for the clinical benefits and cost effectiveness of the Alpha-Stim AID when used in an NHS setting - how well does it work, and does it's use result in cost savings for the NHS.

The study may show that the Alpha-Stim AID should be available on the NHS for patients with suspected GAD.

Participants will have a baseline visit (day 1, visit 1) following identification as potentially eligible. The baseline visit will be face-to-face with a member of the research team, held at routine facilities used by the IAPT service. At the baseline visit, the participant will be consented for participation, have a urine pregnancy test first (if a female of child bearing potential) and the research team will administer the GAD-7 secondly, followed by EQ-5D-5L, WASA, PHQ-9, Athens, and CSRI surveys. Participants will then be instructed on how to use the Alpha-Stim AID device, and will have their first 60 minute, self-directed treatment session at home.

All further visits will be facilitated via telephone, scheduled between the research team and participant, within a 5 calendar day window of each time point.

At visit 2 (week 4), visit 3 (week 6), visit 4 (week 8), visit 5 (week 12) and visit 6 (week 24), the research team will administer the GAD-7, EQ-5D-5L, WASA, PHQ-9 and Athens. The CSRI will be repeated only at visit 5 and 6. Compliance with the 60 minute daily treatment session will also be assessed during the 6 or 12 week treatment window, in addition to any adverse events.

The 60-minute self-directed Alpha-Stim AID treatment sessions are undertaken at participant's home, on a daily basis for 6 weeks for all participants. During this 6-week period, participants will be on the waiting list for high intensity psychological therapy interventions.

Following 6 weeks of Alpha-Stim AID CES treatment, participants have the option to receive a further 6 weeks of treatment, which is likely to coincide with start of high intensity psychological therapy interventions as clinically indicated.

Following a maximum of 12 weeks' treatment with Alpha-Stim AID CES, all participants will cease to receive treatment on study.

All participants will continue to receive standard care assessment, as undertaken by the NHS IAPT service, standard care high intensity psychological therapy interventions as clinically indicated and provided by the NHS IAPT service, and standard care pharmacological treatments as prescribed by the participant's GP. Participation in this study will not influence nor compromise standard care treatment - all study procedures are additional to standard care. Participation in the study will have no impact upon the duration of the waiting time for high intensity psychological therapy interventions.

Inclusion Criteria:

• Primary working diagnosis of moderate-to-severe GAD indicated via a GAD-7 score of 10 or more at baseline visit
• Previous treatment within an IAPT service with step two low intensity psychological therapy intervention
• Indicated for step three high intensity psychological therapy intervention and on the waiting list
• Capable of giving informed consent
• Female participants of child-bearing potential must have a negative urine human chorionic gonadotropin dipstick pregnancy test
• Female participants of child-bearing potential must be practising a highly effective method of contraception (failure rate of less than 1% per year when used consistently and correctly and agree to remain on a highly effective method throughout the 6 or 12 week treatment period. Examples of highly effective contraceptives include: barrier condoms, intrauterine device (IUD), intrauterine hormone-releasing system (IUS), vasectomised partner, sexual abstinence (refraining from heterosexual intercourse), and oestrogen and progestogen containing hormonal contraception associated with ovulation.
• 18 years of age or above at baseline visit
• Able to understand written and verbal English

Exclusion Criteria:

• Primary working diagnosis of a mental disorder other than moderate-to-severe GAD (but other mental and anxiety disorders as secondary comorbidities is not an exclusion criteria)
• No previous treatment within an IAPT service with step two low intensity psychological therapy intervention
• Not indicated for step three high intensity psychological therapy intervention and not on the waiting list
• Requiring urgent clinical care
• Female participants of child-bearing potential with a positive urine human chorionic gonadotropin dipstick pregnancy test
• Female participants of child-bearing potential not willing to practice a highly effective method of contraception during the treatment period
• Implantation with a pace maker
• Implantation with an implantable cardioverter defibrillator (ICD)
• Incapable of giving informed consent
• 17 years of age or less at baseline visit
• Unable to understand written and verbal English

Anonymised data will form part of the final study report which will be used for submission to the UK National Institute for Clinical Excellence.