Anthropometric data and nutritional status

The anthropometric data collected are shown in Table 4. Most of the selected studies (22/30) assessed weight, height, and BMI: information was available for 2912 patients (57.6%), and among them 82.4% were described by mean and standard deviation or median and with z-score assessment. Regarding nutritional status, 513 patients (10.1%) were classified according to WHO criteria⁽⁴⁶⁾ as: underweight (13.2%), normal weight (48.0%), overweight (27.9%), and obese (10.9%). Waist circumference data were collected in the cross-sectional study by Amzali and collaborators^{(Reference Amzali, Wilson, Bommart, Picot, Galas and Mercier5)} and in the clinical trial by Billich et al.^{(Reference Billich, Bray, Truby, Evans, Carroll and de Valle24)}; data were available for 211 patients (4.2%), expressed as mean and standard deviation or median. In Nishizawa’s observational study^{(Reference Nishizawa and Nakamura37)}, the circumference of the lower limb was assessed as an instrument to quantify muscle mass. In eight studies, data about body composition were available: five studies used bio-impedance^{(Reference Amzali, Wilson, Bommart, Picot, Galas and Mercier5,Reference López-Gómez, Ballesteros-Pomar, Torres-Torres, De la Maza, Penacho-Lázaro and Palacio-Mures34,Reference Sechi, Zuccarelli, Grassi, Frangiamore, De Amicis and Marzorati39,Reference van Hees, Knuijt, Dicke, Groothuis, Raaphorst, Satink and Cup42,Reference Wilson, Bommart, Passerieux, Picot, Mercier and Laoudj-Chenivesse44)} and three used dual-energy X-ray absorptiometry (DEXA) instruments^{(Reference Billich, Evans, Truby, Ryan, Kornberg and Davidson6,Reference Zhang, Qi, Wang, Yang, Shen and Yang11,Reference Davidson, Hughes, Ryan, Kornberg, Cairns and Jones26)} . Analyses of body composition, discriminating between fat mass and lean mass, involved a total of 307 patients (6.1%). Finally, malnutrition risk screening was conducted in four studies^{(Reference Naume, Jørgensen, Høi-Hansen, Born, Vissing and Borgwardt10,Reference Zhang, Qi, Wang, Yang, Shen and Yang11,Reference López-Gómez, Ballesteros-Pomar, Torres-Torres, De la Maza, Penacho-Lázaro and Palacio-Mures34)} for a total of 234 patients (4.6%), of whom 27.3% (n = 64) were found to be at risk of severe malnutrition. The most detailed results on malnutrition risk were obtained by Forgues and colleagues^{(Reference Naume, Jørgensen, Høi-Hansen, Born, Vissing and Borgwardt10)}, using the Seniors in the Community Risk Evaluation for Eating and Nutrition (SCREEN II) score, and by Lopez-Gomez^{(Reference López-Gómez, Ballesteros-Pomar, Torres-Torres, De la Maza, Penacho-Lázaro and Palacio-Mures34)}, using the Subjective Global Assessment (SGA) screening tool according to GLIM criteria.

In detail, Forgues et al.^{(Reference Naume, Jørgensen, Høi-Hansen, Born, Vissing and Borgwardt10)} found that 82% of patients with oculopharyngeal muscular dystrophy were at risk for malnutrition, often associated with dysphagia. Lopez-Gomez^{(Reference López-Gómez, Ballesteros-Pomar, Torres-Torres, De la Maza, Penacho-Lázaro and Palacio-Mures34)}, in his research on ALS patients, noted that nearly half of patients (48%) were screened for malnutrition and that those with worsened nutritional status had a lower life expectancy than those in optimal nutritional condition.

In such heterogeneous and progressive diseases, nutritional status changes greatly, and in observational studies performed by Naume and by Chou^{(Reference Chou, Lindeback, D’Silva, Sampaio, Neville and Farrar7,Reference Zhang, Qi, Wang, Yang, Shen and Yang11)} , more than 50% of patients had inadequate body weight, ranging from overweight and obesity in Duchenne muscular dystrophy in paediatric patients, to underweight in other conditions such as motor neuron disease, muscular spinal atrophy, and myotonic dystrophy type 1.

Table 5 details data about diet and nutrition and all the other available lifestyle factors, if addressed (physical activity, smoking and/or alcohol dependence, sleep quality, psychological and emotional conditions, and patients’ perceptions). Seven studies (23.3%) examined three or more aspects of lifestyle, eight studies (26.7%) focused on two aspects, and 15 articles (50.0%) examined a single aspect of lifestyle. None provided a comprehensive analysis of all relevant lifestyle factors in these conditions.

The summary of key information extracted from selected articles, such as the type of study, country, sample size, and all aspects of lifestyle investigated, is reported in Table 6. The evaluation of the methodological quality of the selected studies is reported in Supplementary Table S1.

A descriptive analysis of diet and nutrition and of any other addressed lifestyle factors (including physical activity, sleep quality, smoking and alcohol consumption habits, and emotional perception and care) was performed.

Diet and nutrition

Diet and/or nutrition were investigated in 21 studies (12 observational and 9 clinical trials), with data from 1299 patients (25.7% of the selected total sample). In five intervention studies^{(Reference Dorst, Doenz, Kandler, Dreyhaupt, Tumani and Witzel29,Reference Gazzellone, Lanteigne, Gammage, Fajardo and Ditor31,Reference Ludolph, Dorst, Dreyhaupt, Weishaupt, Kassubek and Weiland35,Reference Sechi, Zuccarelli, Grassi, Frangiamore, De Amicis and Marzorati39,Reference Staretz-Chacham, Pode-Shakked, Kristal, Abraham, Porper and Wormser40)} the authors investigated the effect of special dietary patterns on patients’ symptoms and/or life expectancy. Specifically, in the work of Dorst et al. and Ludolph et al.^{(Reference Dorst, Doenz, Kandler, Dreyhaupt, Tumani and Witzel29,Reference Ludolph, Dorst, Dreyhaupt, Weishaupt, Kassubek and Weiland35)} , the effect of a high-calorie diet was evaluated in comparison to a control group without supplementation, while in the study of Gazzellone et al.^{(Reference Gazzellone, Lanteigne, Gammage, Fajardo and Ditor31)} the ‘Mad Dog Diet’, an anti-inflammatory diet programme, was tested. In the study of Sechi et al.^{(Reference Sechi, Zuccarelli, Grassi, Frangiamore, De Amicis and Marzorati39)}, the effect of a high-protein diet combined with exercise was compared to the exercise programme alone, without any nutritional intervention. The work conducted by the Staretz-Chacham^{(Reference Staretz-Chacham, Pode-Shakked, Kristal, Abraham, Porper and Wormser40)} research group evaluated the effect of a restrictive ketogenic diet on a small group of patients. Specific supplementations evaluated in patients with DMD or FSHD were effective in improving motor performance, and in the second group of patients, at a statistically significant threshold^{(Reference Davidson, Hughes, Ryan, Kornberg, Cairns and Jones26,Reference Wilson, Bommart, Passerieux, Picot, Mercier and Laoudj-Chenivesse44)} . The family-centred intensive lifestyle and weight management programme specifically studied for DMD patients by Billich and collaborators^{(Reference Billich, Bray, Truby, Evans, Carroll and de Valle24)} has been very successful both in terms of patients’ satisfaction and QoL.

None of the selected studies considered adherence to the Mediterranean diet or proposed an intervention based on a Mediterranean dietary pattern. Only the Mad Dog Diet proposed by Gazzellone’s group^{(Reference Gazzellone, Lanteigne, Gammage, Fajardo and Ditor31)} shares common elements with the Mediterranean diet, such as the use of plant-based foods rich in antioxidants, fibre, and omega-3, and a reduced intake of refined and ultra-processed foods. However, this is not an intervention based on the Mediterranean diet.

Dietary intakes, expressed as energy and macro- and micronutrient composition, collected through food diaries, food frequencies questionnaires, or interviews, were evaluated in 13 observational studies^{(Reference Amzali, Wilson, Bommart, Picot, Galas and Mercier5,Reference Billich, Evans, Truby, Ryan, Kornberg and Davidson6,Reference Naume, Jørgensen, Høi-Hansen, Born, Vissing and Borgwardt10,Reference Zhang, Qi, Wang, Yang, Shen and Yang11,Reference Andersen, Aadahl and Vissing23,Reference Billich, Bray, Truby, Evans, Carroll and de Valle24,Reference Dietvorst, Bot, Van Der Holst and Niks27,Reference Kim, Jin, Kim and Park33,Reference López-Gómez, Ballesteros-Pomar, Torres-Torres, De la Maza, Penacho-Lázaro and Palacio-Mures34,Reference Uçar, Altınok, Mansuroglu, Canda, Yazıcı and Çelik41,Reference van Hees, Knuijt, Dicke, Groothuis, Raaphorst, Satink and Cup42,Reference Yamamoto, Mori-Yoshimura, Oya, Komaki and Takahashi45)} . Dietvost^{(Reference Dietvorst, Bot, Van Der Holst and Niks27)} found that intake of fibre, nuts, and dairy products, as well as liquids, was significantly lower than in a healthy population and below the recommended thresholds; these data were confirmed, especially with regard to protein and fibre, by van Hees and collaborators^{(Reference van Hees, Knuijt, Dicke, Groothuis, Raaphorst, Satink and Cup42)}. Billich and Yamamoto^{(Reference Billich, Bray, Truby, Evans, Carroll and de Valle24,Reference Yamamoto, Mori-Yoshimura, Oya, Komaki and Takahashi45)} evaluated patients’ refusal or avoidance behaviour with respect to certain foods or textures, and Chou^{(Reference Chou, Lindeback, D’Silva, Sampaio, Neville and Farrar7)} investigated how many of the recruited subjects had received dietary advice from a nutrition specialist. Finally, Billich^{(Reference Billich, Bray, Truby, Evans, Ryan and Carroll25)} reported that, according to caregivers, patients experienced an increased appetite and often ate discretionary foods.

In clinical trials based on targeted dietary interventions, in which caloric and macro- and micronutrient intakes were optimised, an improvement of motor skills, expressed as increased fatigue tolerance, was observed in different pathologic conditions. In the presence of overweight and/or obesity, an improvement in BMI was observed, as well as a reduction of waist circumference^{(Reference Billich, Bray, Truby, Evans, Carroll and de Valle24,Reference Davidson, Hughes, Ryan, Kornberg, Cairns and Jones26,Reference Dorst, Doenz, Kandler, Dreyhaupt, Tumani and Witzel29,Reference Gazzellone, Lanteigne, Gammage, Fajardo and Ditor31,Reference Ludolph, Dorst, Dreyhaupt, Weishaupt, Kassubek and Weiland35,Reference Sechi, Zuccarelli, Grassi, Frangiamore, De Amicis and Marzorati39,Reference Wilson, Bommart, Passerieux, Picot, Mercier and Laoudj-Chenivesse44)} . Specific dietary intervention, such as a high-protein diet or a ketogenic diet, was found to be effective in improving some metabolic parameters and motor functions^{(Reference Sechi, Zuccarelli, Grassi, Frangiamore, De Amicis and Marzorati39–Reference Uçar, Altınok, Mansuroglu, Canda, Yazıcı and Çelik41)}. However, none of the clinical trials examined observed a significantly positive correlation between dietary intervention and survival. The study by Gazzellone and co-workers, a randomised controlled trial performed with 11 patients with different pathologic conditions, found a significant correlation between an anti-inflammatory diet, based on the consumption of fresh and minimally processed food, and improvement in depression^{(Reference Gazzellone, Lanteigne, Gammage, Fajardo and Ditor31)}.

Overall, observational studies revealed that macro- and micronutrient intakes were frequently far from international recommended levels^{(Reference Elkady, Ahmed and Abd El- Naby30,47)} , especially for protein^{(Reference Amzali, Wilson, Bommart, Picot, Galas and Mercier5,Reference Billich, Evans, Truby, Ryan, Kornberg and Davidson6,Reference Naume, Jørgensen, Høi-Hansen, Born, Vissing and Borgwardt10,Reference Zhang, Qi, Wang, Yang, Shen and Yang11,Reference Elkady, Ahmed and Abd El- Naby30,Reference Kim, Jin, Kim and Park33,Reference López-Gómez, Ballesteros-Pomar, Torres-Torres, De la Maza, Penacho-Lázaro and Palacio-Mures34)} and lipid intakes^{(Reference Amzali, Wilson, Bommart, Picot, Galas and Mercier5,Reference Kim, Jin, Kim and Park33,Reference López-Gómez, Ballesteros-Pomar, Torres-Torres, De la Maza, Penacho-Lázaro and Palacio-Mures34)} . Vitamin C, zinc, calcium, and vitamin E were frequently insufficient too^{(Reference Amzali, Wilson, Bommart, Picot, Galas and Mercier5,Reference Billich, Evans, Truby, Ryan, Kornberg and Davidson6,Reference Davidson, Hughes, Ryan, Kornberg, Cairns and Jones26)} . Reduced consumption of fresh fruit and vegetables emerged in several studies^{(Reference Amzali, Wilson, Bommart, Picot, Galas and Mercier5,Reference Billich, Evans, Truby, Ryan, Kornberg and Davidson6,Reference Naume, Jørgensen, Høi-Hansen, Born, Vissing and Borgwardt10,Reference Elkady, Ahmed and Abd El- Naby30)} and, as a consequence, levels of dietary fibre were often found to be far below optimal intake levels^{(Reference Chou, Lindeback, D’Silva, Sampaio, Neville and Farrar7,Reference Naume, Jørgensen, Høi-Hansen, Born, Vissing and Borgwardt10,Reference Dietvorst, Bot, Van Der Holst and Niks27,Reference Elkady, Ahmed and Abd El- Naby30)} . Moreover, the analysis of diet quality revealed that many patients consumed foods high in calories, but low in nutrients, and that at least 30% of calories were derived from discretionary foods and drinks^{(Reference Billich, Evans, Truby, Ryan, Kornberg and Davidson6)}.

In ten studies, the use of supplements was reported: four were clinical trials as part of the intervention^{(Reference Billich, Bray, Truby, Evans, Carroll and de Valle24,Reference Davidson, Hughes, Ryan, Kornberg, Cairns and Jones26,Reference Staretz-Chacham, Pode-Shakked, Kristal, Abraham, Porper and Wormser40,Reference Wilson, Bommart, Passerieux, Picot, Mercier and Laoudj-Chenivesse44)} , while in the other contexts both commercial multivitamins and targeted supplements, such as vitamin D, calcium, and omega-3, were independently consumed^{(Reference Billich, Evans, Truby, Ryan, Kornberg and Davidson6,Reference Naume, Jørgensen, Høi-Hansen, Born, Vissing and Borgwardt10,Reference Zhang, Qi, Wang, Yang, Shen and Yang11,Reference Kim, Jin, Kim and Park33,Reference Uçar, Altınok, Mansuroglu, Canda, Yazıcı and Çelik41)} .

In the intervention study conducted by Wilson and colleagues, a supplementation of vitamin C, vitamin E, zinc, and selenium significantly improved muscle volume and function in patients with FSHD^{(Reference Wilson, Bommart, Passerieux, Picot, Mercier and Laoudj-Chenivesse44)}.

Finally, nutrition education interventions, in which both patients and caregivers or targeting groups were involved, were found to be effective in improving eating habits and the management of daily meals^{(Reference Billich, Bray, Truby, Evans, Ryan and Carroll25,Reference van Hees, Knuijt, Dicke, Groothuis, Raaphorst, Satink and Cup42)} .

Other lifestyle factors

In addition to diet and nutrition, all other lifestyle factors that emerged in this literature review were analysed.

Physical activity (PA) was analysed in 16 studies (53.3%), including 3 clinical trials and 13 observational studies, and involving a total of 4220 patients out of 5055 (83.5%) (Table 5).

The studies by Amzali et al.^{(Reference Amzali, Wilson, Bommart, Picot, Galas and Mercier5)}, Andersen et al.^{(Reference Andersen, Aadahl and Vissing23)}, Billich et al.^{(Reference Billich, Evans, Truby, Ryan, Kornberg and Davidson6)}, Davidson et al.^{(Reference Davidson, Hughes, Ryan, Kornberg, Cairns and Jones26)} Dong et al.^{(Reference Dong, Chong, Wu, Kaminski, Cutter and Xu28)}, Elkady et al.^{(Reference Elkady, Ahmed and Abd El- Naby30)}, Jackson et al.^{(Reference Jackson, Parthan, Lauher-Charest, Broderick, Law and Barnett32)}, Karazi et al.^{(Reference Karazi, Coppers, Maas, Cup, Bloemen and Voet21)}, Kim et al.^{(Reference Kim, Jin, Kim and Park33)}, Nishizawa et al.^{(Reference Nishizawa and Nakamura37)}, Said et al.^{(Reference Said and Alhumaid38)}, and Ucar et al.^{(Reference Uçar, Altınok, Mansuroglu, Canda, Yazıcı and Çelik41)} collected data on participants’ actual physical activity and/or motor function, using assessment tools and scales not always comparable.

Assessment of PA has been conducted through questionnaires, interviews, and/or rating scales in 13 studies; more specific instruments, such as accelerometers^{(Reference Andersen, Aadahl and Vissing23)}, tests conducted with health professionals^{(Reference Billich, Evans, Truby, Ryan, Kornberg and Davidson6,Reference Sechi, Zuccarelli, Grassi, Frangiamore, De Amicis and Marzorati39)} , and the ‘6-Minute Walk Distance (6MWD)’^{(Reference Billich, Bray, Truby, Evans, Carroll and de Valle24,Reference Davidson, Hughes, Ryan, Kornberg, Cairns and Jones26,Reference Uçar, Altınok, Mansuroglu, Canda, Yazıcı and Çelik41)} were used in six papers.

Three intervention studies^{(Reference Billich, Bray, Truby, Evans, Carroll and de Valle24,Reference Davidson, Hughes, Ryan, Kornberg, Cairns and Jones26,Reference Sechi, Zuccarelli, Grassi, Frangiamore, De Amicis and Marzorati39)} examined motor function and physical activity in patients with neuromuscular diseases. The pilot study by Billich et al. showed a trend toward improved motor function and fatigue tolerance, although not statistically significant, after a lifestyle and weight management programme^{(Reference Billich, Bray, Truby, Evans, Carroll and de Valle24)}.

In the work of Davidson et al., a significant increase in 6MWD test performance and an improvement of daily activity parameters were observed after the use of an enhanced supplement. Body composition and quality of life of these DMD patients did not change^{(Reference Davidson, Hughes, Ryan, Kornberg, Cairns and Jones26)}. Sechi’s group observed that an exercise programme combined with a high-protein diet improved aerobic function, lung capacity, and QoL in late-onset Pompe disease patients. In this intervention study, a personalised exercise training programme, combined with a high-protein diet, could significantly improve maximal muscular performance, exercise tolerance, vitality, and general health in comparison to the control group^{(Reference Sechi, Zuccarelli, Grassi, Frangiamore, De Amicis and Marzorati39)}.

Data from observational studies showed that, even taking into account different disease conditions, the physical activity level of most patients with neuromuscular diseases was overall lower than the minimum level of WHO recommendations⁽⁴⁸⁾. In addition, this tendency toward a reduced physical activity was more pronounced among females than males^{(Reference Andersen, Aadahl, Vissing and Knak22,Reference Andersen, Aadahl and Vissing23,Reference Dong, Chong, Wu, Kaminski, Cutter and Xu28,Reference Said and Alhumaid38)} . The extensive observational study performed by Dong and co-workers found that women with MG had a significantly worse physical quality of life and a lower level of active lifestyle in comparison to men with the same clinical condition (p < 0.001 and p < 0.01, respectively)^{(Reference Dong, Chong, Wu, Kaminski, Cutter and Xu28)}. Andersen et al. observed that 53% of patients with MG had a low level of PA, especially among females. Authors found a significant correlation between poor PA and higher BMI, older age, presence of comorbidities, reduced QoL, sleep disorders, and increased levels of fatigue^{(Reference Andersen, Aadahl, Vissing and Knak22)}. In a subsequent study by Andersen and collaborators, conducted by accelerometer and IPAQ test, it was observed that 48% of patients with MG did not meet the moderate intensity recommendations^{(Reference Andersen, Aadahl and Vissing23)}. Jackson et al. observed that participation in sports was challenging for patients with MG, and symptoms often induced withdrawal of PA^{(Reference Jackson, Parthan, Lauher-Charest, Broderick, Law and Barnett32)}. In the work of Amzali, 84% of patients with FHSD reported low level of PA, and in women it was significantly lower than in men. Simultaneously, PA was positively related to younger age, daily energy intake, and zinc blood level^{(Reference Amzali, Wilson, Bommart, Picot, Galas and Mercier5)}. The study of Billich et al.^{(Reference Billich, Evans, Truby, Ryan, Kornberg and Davidson6)} reported a weak positive correlation between motor performance and energy intake (p < 0.01) and Nishizawa and collaborators observed that a more sedentary lifestyle and lack of PA significantly decreased motor performance of patients with DMD^{(Reference Karazi, Coppers, Maas, Cup, Bloemen and Voet21,Reference Nishizawa and Nakamura37)} . In the observational transversal study of Karazi, 47% of the patients with myopathy did not perform vigorous PA, 29% of the patients did not perform moderate PA, and 13% did not walk for at least ten minutes a day^{(Reference Karazi, Coppers, Maas, Cup, Bloemen and Voet21,Reference Kim, Jin, Kim and Park33)} , while in the study of Kim on ALS patients, 61% of subjects were reported to do exercise more than once a week^{(Reference Kim, Jin, Kim and Park33)}.

In the prospective study by Ucar et al.^{(Reference Uçar, Altınok, Mansuroglu, Canda, Yazıcı and Çelik41)}, it was observed that a diet high in protein and fat led to increased exercise tolerance and motor function in paediatric patients with glycogen storage disease. Moreover, the daily activity questionnaire scores significantly improved in comparison to the initial self-evaluation^{(Reference Uçar, Altınok, Mansuroglu, Canda, Yazıcı and Çelik41)}. Finally, Said and collaborators observed that more than 60% of patients, especially men, with different disabilities involved in the observational study, met the minimum standard of PA specified by WHO. Authors also observed that PA was significantly related to education level, type of disability (poliomyelitis exhibited the highest level of PA), and self-rated health^{(Reference Said and Alhumaid38)}.

With regard to other lifestyle factors that emerged from this review, sleep quality was assessed in two observational studies, both conducted on patients suffering from MG^{(Reference Andersen, Aadahl, Vissing and Knak22,Reference Jackson, Parthan, Lauher-Charest, Broderick, Law and Barnett32)} . Self-reported sleep quality and sleep disturbance during the previous two weeks were measured by Andersen and colleges using the Insomnia Severity Index, with 55% of patients reporting insomnia. In addition, significantly more sleep problems were reported in the group of patients with lower physical activity. Insomnia also correlated with general fatigue, reduced activity and motivation, and mental fatigue^{(Reference Andersen, Aadahl, Vissing and Knak22)}.

Jackson and co-workers conducted structured interviews, and the common symptoms identified by patients revealed that the main sleep problems were caused by respiratory problems or preoccupation with illness^{(Reference Jackson, Parthan, Lauher-Charest, Broderick, Law and Barnett32)}.

Alcohol consumption and tobacco use were investigated in two articles^{(Reference Kim, Jin, Kim and Park33,Reference McMillan, Bowen, Bayan, Kasperbauer and Ekbom36)} : in the papers by Kim et al. and by McMillan et al., alcohol consumption and smoking status were obtained by interviews and reported in the results as ‘current’, ‘former’, or ‘never’ drinking or smoking. Notably, in both studies, authors did not look for any correlation between tobacco use or alcohol consumption and pathological condition, QoL, or survival^{(Reference Kim, Jin, Kim and Park33,Reference McMillan, Bowen, Bayan, Kasperbauer and Ekbom36)} .

No data on abuse of substances were identified in the articles selected in this systematic review.

The emotional and psychological status of patients was investigated in 11 studies (36.7%), 4 clinical trials^{(Reference Billich, Bray, Truby, Evans, Carroll and de Valle24,Reference Gazzellone, Lanteigne, Gammage, Fajardo and Ditor31,Reference Ludolph, Dorst, Dreyhaupt, Weishaupt, Kassubek and Weiland35,Reference Sechi, Zuccarelli, Grassi, Frangiamore, De Amicis and Marzorati39)} and 7 observational studies^{(Reference Andersen, Aadahl, Vissing and Knak22,Reference Billich, Bray, Truby, Evans, Ryan and Carroll25,Reference Dong, Chong, Wu, Kaminski, Cutter and Xu28,Reference Elkady, Ahmed and Abd El- Naby30,Reference Jackson, Parthan, Lauher-Charest, Broderick, Law and Barnett32,Reference Said and Alhumaid38,Reference Walker, Mistry, Amin, McAdam, Kalnins and Lui43)} , with data available for 3219 of 5055 patients (63.7%). The most frequently investigated emotional aspects involved conditions of anxiety and depression, which were examined in the work of Andersen et al., Billich et al., Dong et al., Gazzellone et al., Jackson et al., and Ludolph et al.^{(Reference Andersen, Aadahl, Vissing and Knak22,Reference Billich, Bray, Truby, Evans, Carroll and de Valle24,Reference Dong, Chong, Wu, Kaminski, Cutter and Xu28,Reference Gazzellone, Lanteigne, Gammage, Fajardo and Ditor31,Reference Jackson, Parthan, Lauher-Charest, Broderick, Law and Barnett32,Reference Ludolph, Dorst, Dreyhaupt, Weishaupt, Kassubek and Weiland35)} . Other studies explored the relationship between emotions and eating behaviours or focused attention on stress management, emotional well-being, and vitality of patients^{(Reference Billich, Bray, Truby, Evans, Ryan and Carroll25,Reference Elkady, Ahmed and Abd El- Naby30,Reference Sechi, Zuccarelli, Grassi, Frangiamore, De Amicis and Marzorati39)} . Among clinical trials, of note was the work of Gazzellone and collaborators, where an anti-inflammatory diet succeeded in significantly improving depression status measured by the Centre for Epidemiological Studies Depression Scale (CES-D)^{(Reference Gazzellone, Lanteigne, Gammage, Fajardo and Ditor31)}. Sechi et al. also observed a trend in improvement in emotional state following a combined diet and physical activity intervention, although none of these studies reached statistical significance, probably due to a small sample size^{(Reference Sechi, Zuccarelli, Grassi, Frangiamore, De Amicis and Marzorati39)}. In the study of Ludolph, 3% of the sample reported depression, and the dietary intervention did not significantly change their perceived QoL^{(Reference Ludolph, Dorst, Dreyhaupt, Weishaupt, Kassubek and Weiland35)}. Finally, in Billich’s well-being intervention trial, the impact on anxiety, reported at baseline in three out of eight DMD patients, was not evaluated^{(Reference Billich, Bray, Truby, Evans, Carroll and de Valle24)}.

Data on emotional condition and perception, collected in the different observational studies mainly at baseline, vary greatly, even in similar pathological conditions. In the article of Andersen, 8% of patients with MG reported depression or anxiety, and this condition significantly correlated with fatigue (general, physical, and mental) and reduced activity and motivation^{(Reference Andersen, Aadahl, Vissing and Knak22)}. In the large observational study performed by Dong and co-workers on Chinese patients with MG, depression was reported by 10.1% of men and 10.6% of women, and anxiety by 12.7% of men and 12.5% of women. Authors observed that MG also affected the emotional status in the female population more than in males^{(Reference Dong, Chong, Wu, Kaminski, Cutter and Xu28)}.

In the study by Jackson et al.^{(Reference Jackson, Parthan, Lauher-Charest, Broderick, Law and Barnett32)}, conducted in patients with MS, anxiety and depression affected 82% and 75% of the population, respectively. Moreover, frustration (64% of patients), stress (32%), and discomfort (18%) were reported, and patients referred to difficulties in interpersonal relationships, a sense of misunderstanding by friends and family, anxiety related to social occasions, and a tendency to avoid relational events. Reduced sociality and difficulties in managing relationships both within and outside the family emerge as factors that severely affect the QoL perceived^{(Reference Jackson, Parthan, Lauher-Charest, Broderick, Law and Barnett32)}. Elkady recorded, with the health promotion behaviour scale test, an intermediate level of stress management and self-actualisation among MG patients^{(Reference Elkady, Ahmed and Abd El- Naby30,Reference Said and Alhumaid38)} .

In the study by Said and collaborators, where patients with different NMDs were enrolled, health perception was significantly better in those who were physically active (p < 0.001)^{(Reference Said and Alhumaid38)}.

In projects involving both patients and caregivers in small groups, it was also possible to investigate correlations between pathology, emotions, and eating habits: sadness, depression, anger, boredom, and pleasure were associated with food consumption in 14% of patients with DMD^{(Reference Billich, Bray, Truby, Evans, Ryan and Carroll25)}. In the qualitative study of Walker, through semi-structured interviews on weight management, the psychosocial well-being of boys with DMD and families was discussed, and the importance of an integrated and multidisciplinary approach was highlighted. A higher level of engagement among mothers also emerged^{(Reference Walker, Mistry, Amin, McAdam, Kalnins and Lui43)}.

Primary and secondary endpoints

Among the 30 studies evaluated in this narrative review, 11 enrolled paediatric patients (< 18 years; 36.7%)^{(Reference Billich, Evans, Truby, Ryan, Kornberg and Davidson6,Reference Chou, Lindeback, D’Silva, Sampaio, Neville and Farrar7,Reference Naume, Jørgensen, Høi-Hansen, Born, Vissing and Borgwardt10,Reference Billich, Bray, Truby, Evans, Carroll and de Valle24–Reference Dietvorst, Bot, Van Der Holst and Niks27,Reference Nishizawa and Nakamura37,Reference Staretz-Chacham, Pode-Shakked, Kristal, Abraham, Porper and Wormser40,Reference Uçar, Altınok, Mansuroglu, Canda, Yazıcı and Çelik41,Reference Walker, Mistry, Amin, McAdam, Kalnins and Lui43)} , 9 enrolled young to middle-aged adults (age 18–50 years; 30%)^{(Reference Amzali, Wilson, Bommart, Picot, Galas and Mercier5,Reference Dong, Chong, Wu, Kaminski, Cutter and Xu28,Reference Elkady, Ahmed and Abd El- Naby30,Reference Jackson, Parthan, Lauher-Charest, Broderick, Law and Barnett32,Reference Said and Alhumaid38,Reference Sechi, Zuccarelli, Grassi, Frangiamore, De Amicis and Marzorati39,Reference van Hees, Knuijt, Dicke, Groothuis, Raaphorst, Satink and Cup42,Reference Wilson, Bommart, Passerieux, Picot, Mercier and Laoudj-Chenivesse44,Reference Yamamoto, Mori-Yoshimura, Oya, Komaki and Takahashi45)} , and 10 enrolled adults (mean age >50 years; 33.3%)^{(Reference Forgues, Fortin, Gagnon, Brisson, Mathieu and Brais9,Reference Karazi, Coppers, Maas, Cup, Bloemen and Voet21–Reference Andersen, Aadahl and Vissing23,Reference Dorst, Doenz, Kandler, Dreyhaupt, Tumani and Witzel29,Reference Gazzellone, Lanteigne, Gammage, Fajardo and Ditor31,Reference Kim, Jin, Kim and Park33–Reference McMillan, Bowen, Bayan, Kasperbauer and Ekbom36)} . This age distribution reflects the natural course of these heterogeneous conditions: genetic dystrophies (DMD, SMA) typically manifest during childhood; myopathies and limb-girdle muscular dystrophies tend to manifest in early adulthood; MG, ALS, and inclusion body myositis are predominantly diseases that affect middle-aged and elderly adults.

In this narrative review, we also search for possible correlations of lifestyle on disease course (19 studies) and on QoL (nine studies, four as primary and five as secondary endpoint).

As for changes in pathology-related parameters, the studies vary greatly according to different diseases: in patients with ALS, a higher body weight was positively correlated with a prolonged survival rate, and an increased intake of protein, fats, and meat was positively associated both with long-term survival and symptoms delay^{(Reference Kim, Jin, Kim and Park33)}. A fat-rich diet, even if effective in improving weight gain, caused gastrointestinal side effects in several ALS patients^{(Reference Dorst, Doenz, Kandler, Dreyhaupt, Tumani and Witzel29)}. In the intervention study of Ludolph and collaborators, a high-caloric nutrition programme did not increase the survival time, nor the vital capacity and functionality of ALS patients^{(Reference Ludolph, Dorst, Dreyhaupt, Weishaupt, Kassubek and Weiland35)}.

In MG patients, higher physical activity seems to improve symptoms and fatigue resistance and, globally, these patients registered a better health condition and quality of life^{(Reference Andersen, Aadahl, Vissing and Knak22,Reference Andersen, Aadahl and Vissing23)} . One third of the MS patients involved in the observational study of Elkady achieved a low level of healthy promotion behaviours, including reduced physical activity^{(Reference Karazi, Coppers, Maas, Cup, Bloemen and Voet21,Reference Elkady, Ahmed and Abd El- Naby30)} . Lower physical activity was related to worst parameters and, overall, to a poorer quality of life, also in patients with McArdle disease^{(Reference Karazi, Coppers, Maas, Cup, Bloemen and Voet21)}. Physical activity is one of the aspects of the lifestyle that also affects the disease parameters in patients with DMD. Nishizawa and colleagues observed a significant reduction of motor function in patients with DMD in relation to the movements and travel restriction imposed during Covid-19 pandemic^{(Reference Nishizawa and Nakamura37)}.

Improved functional outcomes and ambulation in patients with DMD were achieved by antioxidant supplementation and higher protein intake^{(Reference Amzali, Wilson, Bommart, Picot, Galas and Mercier5,Reference Davidson, Hughes, Ryan, Kornberg, Cairns and Jones26)} . Personalised dietary interventions, associated with lifestyle for weight management, have been reported by both DMD patients and caregivers to improve physical function and satisfaction^{(Reference Billich, Evans, Truby, Ryan, Kornberg and Davidson6,Reference Billich, Bray, Truby, Evans, Carroll and de Valle24,Reference Billich, Bray, Truby, Evans, Ryan and Carroll25)} . Multidisciplinary interventions, involving both patients and caregivers, created a healthier environment and improved clinical outcomes^{(Reference Said and Alhumaid38,Reference van Hees, Knuijt, Dicke, Groothuis, Raaphorst, Satink and Cup42,Reference Walker, Mistry, Amin, McAdam, Kalnins and Lui43)} . In studies of different types of patients with neuromuscular diseases, it has been observed that a personalised dietary intervention and a multidisciplinary approach over time can improve health condition, including improving depression or mobility^{(Reference Gazzellone, Lanteigne, Gammage, Fajardo and Ditor31,Reference Uçar, Altınok, Mansuroglu, Canda, Yazıcı and Çelik41)} .

Quality of life was measured through validated and standardised questionnaires, which allowed the assessment of various aspects, including physical, psychological, and emotional well-being: PedsQL, tailored for the paediatric population, was used by Billich^{(Reference Billich, Bray, Truby, Evans, Carroll and de Valle24)} and Davidson^{(Reference Davidson, Hughes, Ryan, Kornberg, Cairns and Jones26)}; for the adult population affected by MG, the specific MGQoL-15 was used by Andersen and by Dong^{(Reference Andersen, Aadahl, Vissing and Knak22,Reference Dong, Chong, Wu, Kaminski, Cutter and Xu28)} ; and the SF-36 questionnaire, able to assess eight different areas of daily life, was used by Sechi and Wilson^{(Reference Sechi, Zuccarelli, Grassi, Frangiamore, De Amicis and Marzorati39,Reference Wilson, Bommart, Passerieux, Picot, Mercier and Laoudj-Chenivesse44)} . Due to the different and not comparable assessment methodologies, a comprehensive statistical analysis was not permitted. Improved QoL was observed in some intervention studies: Sechi et al. highlighted that individualised exercise programmes, in combination with tailored nutrition, have led to significant improvements not only in physical function but also in quality of life, particularly with regard to general health (p = 0.031) and vitality (p = 0.031)^{(Reference Sechi, Zuccarelli, Grassi, Frangiamore, De Amicis and Marzorati39,Reference Wilson, Bommart, Passerieux, Picot, Mercier and Laoudj-Chenivesse44)} . Wilson and colleagues observed that antioxidant supplementation, with vitamin C, vitamin E, zinc, and selenium for 17 weeks, significantly improved the QoL of FSHD patients in terms of physical functioning, general health, vitality, emotional role functioning, and mental score. In the clinical trial of Staretz-Chacham, although not significant, a general trend of an increased QoL was observed in the ketogenic diet group^{(Reference Staretz-Chacham, Pode-Shakked, Kristal, Abraham, Porper and Wormser40)}, while in the work of Davidson and Ludolph, performed on patients affected by DMD and ALS respectively, no meaningful improvements in QoL score were detected^{(Reference Davidson, Hughes, Ryan, Kornberg, Cairns and Jones26,Reference Ludolph, Dorst, Dreyhaupt, Weishaupt, Kassubek and Weiland35)} . Observational studies have provided different results regarding QoL: Dong et al. identified that risk factors that could worsen QoL included female sex (p < 0.05), a high number of comorbidities (p < 0.05), and unemployment (p < 0.001), while an active lifestyle had a positive impact on HRQoL (p < 0.001)^{(Reference Dong, Chong, Wu, Kaminski, Cutter and Xu28)}. In the study of Andersen (2021) the MGQoL-15 score was significantly higher in patients regularly involved in PA (p < 0.01)^{(Reference Andersen, Aadahl, Vissing and Knak22)}, a trend also observed in patients with low motor capacity^{(Reference Billich, Bray, Truby, Evans, Carroll and de Valle24,Reference Kim, Jin, Kim and Park33)} . The importance of physical activity as a component of lifestyle has also emerged in the work of Elkady et al. and Ucar et al.^{(Reference Uçar, Altınok, Mansuroglu, Canda, Yazıcı and Çelik41)}, who explored the effect of a high-protein diet and physical activity on increased motor capacity and QoL, with promising although not statistically significant results^{(Reference Elkady, Ahmed and Abd El- Naby30,Reference Uçar, Altınok, Mansuroglu, Canda, Yazıcı and Çelik41)} . QoL is closely related also to the emotional state of patients: negative emotions, such as anxiety, depression, sadness, and frustration, have a direct impact on the quality of social relationships, negatively affecting patients’ overall well-being^{(Reference Billich, Bray, Truby, Evans, Ryan and Carroll25,Reference Sechi, Zuccarelli, Grassi, Frangiamore, De Amicis and Marzorati39)} . Impacts on social functioning, reported by the 96% of patients with MG enrolled in the study of Jackson, which included difficulties in dating, feeling misunderstood by friends and family, feeling uncomfortable/anxious in social situations, and skipping or avoiding social events, have been identified as significantly affecting the perceived QoL^{(Reference Jackson, Parthan, Lauher-Charest, Broderick, Law and Barnett32)}.