There is no cure for Parkinson's disease, resulting in an interest for research in this domain. Non pharmacological measures remain essential, specifically physical activity. Hippotherapy is a nonconventional method which uses the horse in addition to standard care. The goal being to improve or maintain the gains of the person through cognitive, sensorial and motor stimulation, with the aim of improving quality of life and maintaining independence. With this in mind, the researchers propose to evaluate quality of life as the main criterion, using the PDQ8 scale validated for this disease. The researchers hope results will lead to the coverage of the costs of non-conventional therapies such as hippotherapy by social security services.

Parkinson's disease is a degenerative disorder with a prevalence of 2.50 patients per 1,000 people in 2015. Prevalence and incidence increase progressively with age up to the age of 80; more than half of patients are over 75.

There are two main types of Parkinson's disease in the elderly:

1. Parkinson's disease begins late, after the age of 75, and the disease may progress relatively slowly if there are no co-morbidities.
2. Or Parkinson's disease has been evolving for a long time, starting on average around the age of 55, and in this situation a number of difficulties arise depending on how long the disease has been present, the association of motor and non-motor fluctuations, the emergence of axonal signs and a decline in the severity of the disease, signs and a decline in cognitive function.

The therapeutic management of Parkinson's disease in the elderly must be assessed on a case-by-case basis. The efficacy/tolerance ratio of dopaminergic treatments must be taken into account.

In Alzheimer's disease (AD), it has been shown that aerobic exercise can delay cognitive decline. With this in mind, the researchers would like to propose a new and original approach using equitherapy in elderly Parkinson's patients.

The aim of this therapy will be to improve patients' quality of life, particularly in terms of well-being, maintain and encourage their autonomy and promote social interaction.

Equitherapy is an unconventional therapy which uses the horse as a complement to the treatment. For the EQUIDIA study, the researchers have suggested using the PDQ-8 score, validated for this condition, to evaluate quality of life as well as well-being and cognitive capacity for a group of Parkinson's patients over the age of 75 following 6 therapy sessions.Their Parkinson's diagnosis is to be confirmed through morphological and phase contrast MRI. The sessions will take place at the same interval of time following the administration of any dopaminergic medication. Progress will be recorded by the hippotherapy therapist using an evaluation developed by a horse-riding instructor. Sessions will be evaluated using inertia measurement devices to analyze quality of movement and the effect of specific activites with the horse.

Inclusion Criteria:

• Age ≥ 75 years with PD according to Movement Disorders Society criteria (2015).
• Clinical diagnosis of Alzheimer's disease
• Has been on stable antiparkinsonian treatment for less than 3 months.
• Ability to understand the principle of the study as well as its risks.
• Written consent to participate in the trial.
• Have social insurance
• Agree to comply with all safety procedures during the study and its duration.
• Ability to understand and freely give consent
• Patient affiliated to social security or entitled beneficiary
• Autonomy preserved

Exclusion criteria :

• age <75 years
• refusal to sign consent
• MOCA <23
• Presence of major behavioural problems that do not allow MRI to be performed under optimal conditions
• Subjects unable to receive informed information, unable to participate in the study as a whole
• Subjects with a diagnosis of atypical parkinsonian syndrome (Lewy body disease, progressive supranuclear palsy, multisystem atrophy, cortico-basal degeneration, etc.).
• A classic contraindication to an MRI examination: claustrophobia, presence of incompatible foreign material,
• Subjects who have practised horse riding at a high level, animal phobias, wish to stop studying, etc.
• No affiliation to a social security scheme
• Antiparkinsonian treatment has not been stable for at least 3 months.
• People under protective supervision (guardianship, curatorship)
• People under family guardianship are also excluded, as are people for whom a mandate for future protection has been activated.