In a clinical study on 43 Parkinson disease patients in Egypt, Elwan et al. (1996) found that age causes deterioration of intentional memory instead of perception indicating that cognitive impairment in PD patients could be attributed to a process other than age such as complex cognitive changes. Intentional memory deterioration may be caused by sub-cortex atrophy and is more pronounced in patients with dementia.

In a prevalence study conducted in Benghazi, Libya, between 1982 and 1984, Ashok et al. (1986) defined PD as the presence of two or more cardinal signs (rest tremor, bradykinesia, rigidity, and impaired postural and righting reflexes), but no exclusion criteria were stated. The size of the population studied was 518,745 and the point prevalence of PD was 31.4/100,000 (the prevalence date was 1 January 1985) and the incidence at 4.5 per 100,000 person/year; however, no sex- or age-specific data were provided. For those older than 50 years of age, the prevalence of PD was 285.1/100,000. The sudy finally indicated that the risk of Parkinson disease is medial between other ethnicities and is close to that of Sardinians.

In a first-of-its-kind review on PD in the Arab world, Benamer et al. (2008) noted that the study of Ashok et al. (1986) may be the only Arab epidemiological study declaring the incidence rate to be lower than in other populations.

Hamad et al. (2004) undertook a first-of-its-kind study in the region to determine the different sub-types of dementia amongst a total of 134 Qatari patients diagnosed between 1997 and 2003. Dementia was defined according to the DSM IV criteria, while cognitive function was graded by a Modified Minimal Mental State Examination (MMSE). Patients with cognitive impairment were further evaluated by a neurologist or a geriatrist. Brain CT was analyzed for all patients, and those with abnormal CT (35 patients) were further evaluated by brain MRI. CT was able to identify Parkinson Disease with dementia in eight (6%) of the patients (five males, three females). Hamad et al. (2004) stressed upon the need to educate physicians on the early detection of cognitive impairment and raising awareness among the public about diseases causing dementia and the possible preventive measures.

Al Rajeh (1993) was the first to indicate the prevalence rate of PD in Saudi Arabia to be as high as 27 per 100,000. The study was conducted on the population of Thugbah with a screening interview followed by a neurologist assessment including family members of subjects with an abnormal result. Consanguinity existed in 54.6% of cases. Subsequently, Al Rajeh (1994) conducted a retrospective study on movement disorders in a pediatrics and adult neurology clinics with 137 patients (93 males and 44 females), 84% of which were Saudi nationals. Of the 71 cases of parkinsonism, 64 cases were assigned to Parkinson disease. [Al Rajeh S, Awada A, Bademosi O, Ismail H. Spectrum of movement disorders in a Saudi university hospital. Saudi Med J. 1994; 15(2):138-142.]

In a later study about dementia in Saudi Arabia, Ogunniyi et al. (1998) investigated the types of dementia presented in 77 patients of a hospital in Saudi Arabia following the DSM-IV and ICD 10 criteria and established dementia with Parkinson disease in 7.8% of the cases.

Al-Bunyan (2000) studied 54 Parkinson disease patients (41 males and 13 females) in a clinical and survey at the King Khaled University Hospital from 1985 to 1997. Parkinson disease was diagnosed in the presence of two or more of the cardinal signs: resting tremor, rigidity, akinesia and impaired postular reflexes for a period of at least one year. The patients were between 60 and 89 years old, six of them had diabetes mellitus, five had a previous stroke, and five others had hypertension. Family history was only obtained in two cases. Excluding factors included remittance, oculogyric crisis, a history of previous neuroleptic therapy and a history of encephalitis lethargica. After subjecting the patients to further clinical and electrophysiological examination, Al-Bunyan (2000) summarized that Parkinson disease in Saudi Arabian patients has a similar clinical picture to the disease present in other populations.

In a door-to-door study conducted in Kelibia, Tunisia, in 1985, using the WHO protocol in a clearly defined population that comprised 34,874 subjects, Attia Romdhane et al. (1993) calculated the crude prevalence ratio of PD to be 43/100,000, whereas the age-adjusted prevalence ratio (adjusted to the world population) was 68/100,000. The prevalence figures were 216/100,000 in subjects 40 years of age or older and 296/100,000 in subject 50 years of age or older. Amongst the disorders studied, such as stroke and migraine, Parkinson disease and epilepsy were found to be as prevalent as it does in other populations.

The inheritance pattern of Parkinson disease has been determined as heterogeneous by Gouder-Khouja et al. (2000) and onset occurred earlier than sporadic Parkinson disease. The 21 families studied comprised 44 men and 44 women and were split in single-generation families, where the disease was diagnosed in individuals of one and the same generation and multigenerational families where the disease encompasses more than one generation. Pedigree analysis showed autosomal recessive patterns in single-generation families with a higher parental consanguinity and autosomal dominant patterns in multigenerational families with reduced penetrance.